Showing posts with label Success. Show all posts
Showing posts with label Success. Show all posts
Friday, April 6, 2012
Saturday, March 24, 2012
Choosing the right print coating
The right coating can help protect the printed piece or add a creative dimension. The results will usually look best on coated paper because the hard, nonporous surface of coated paper holds the coating on the top of the paper rather than have it disappear by being absorbed into the paper. Even when trying to achieve an overall matte effect, a gloss coated sheet is usually the best paper choice and the gloss finish on the paper will provide superior printability. In general, uncoated papers do not benefit very much in appearance from coatings or varnishes, although either will help prevent rubbing in areas of heavy ink coverage. Matte or satin varnishes or coatings are the best choices for uncoated stocks.Varnishes
Varnishes are applied on press like any other ink and can be tinted to create a special effect. Although gloss and matte varnishes are typically used as spot or overall coatings, they can also be incorporated in the process or spot color inks in order to provide a unique look to the presswork. They can be wet trapped (i.e. printed at the same time as the other inks) or dry trapped (i.e. printed as a second pass through the press after the other inks have dried). Dry trapping provides a superior result but is a more expensive process. Varnishes may yellow with age, however, this is usually not noticeable when the varnish is used over process colors, but it is noticeable when the varnish is applied over unprinted paper. They also require the use of offset spray powder on press to keep the printed sheets from sticking together before the varnish is completely cured. The powder left behind can adversely affect the look and feel of the finished piece.
Gloss varnish: This coating can be applied overall or in spot areas with high precision. A gloss varnish increases the saturation and depth of colors while improving image contrast. It provides good protection against rub-off but some fingerprinting will be apparent on dark or light colors. Because the gloss finish is highly reflective it creates glare on the surface of the print which may impair the readability of text.
Matte varnish: This ink protects the sheet with a non-reflective coating which enhances the readability of text-heavy pages. Using a matte varnish over images tends to flatten and soften them, but it can provide a lush tactile quality to the paper surface. As with a gloss varnish the coating is printed with a litho plate, so it can also be spot applied with high precision. It is more resistant to fingerprinting than a gloss varnish however it will tend to scuff or gloss up with wear. If the presswork is packed for delivery it's a good idea to place blank paper between the printed items to prevent them rubbing against each other and scuffing.
Satin varnish: This coating is created by mixing gloss and matte varnishes together and offers an intermediate level of shine, with good scuff resistance.
Opaque varnish: Adding a small amount of opaque white to a varnish can give it a slight opacity which can help in creating a stronger separation between a gloss and a matte varnish. Adding a slight contamination with silver ink can accomplish the same effect on very dark colors.
Strike-through matte varnish: A litho plate printed varnish that, when overprinted with an overall gloss UV or aqueous coating, will create a visual separation between areas of a press sheet. Gloss/matte effects work best on dark colors, or when enhance by the content of underlying graphics.
Aqueous coating
These water-based coatings are applied using a rubber blanket inline on a special dedicated press unit. among the most commonly used coatings available today and provide good protection from fingerprints and other blemishes. Aqueous coatings are less likely to yellow and are more environmentally friendly than varnishes. They dry faster than varnishes which translates into faster turnaround times on press. They don't require spray powder. Because they seal the ink from the air, they can help prevent metallic inks from tarnishing. Aqueous coatings can cause certain spot colors such as reflex blue, rhodamine, violet, purple, and PMS warm red to change color. Sometimes within a few minutes but also over time - months or even years later. Because the aqueous coating is water-based an typically applied over the entire sheet it is best to use at least an 80# text weight or heavier paper to prevent the paper from curling, distorted, or wrinkled.
Gloss aqueous: Usually applied as an overall coating, gloss aqueous offers better protection than gloss varnish. It is sometimes applied to a spot area however this requires cutting an expensive press blanket. It also results in edges that are not as sharp as a spot varnish and registration that is less precise. The surface dries instantly, making it an excellent choice for short run work-and-turn projects. Aqueous coatings help disguise surface flaws and roughness in the non-print areas of inexpensive papers. The gloss finish improves the apparent saturation of ink but somewhat reduces the readability of text.
Matte aqueous: A scuff resistant matte coating which, as with gloss aqueous, is generally applied overall. And like a matte varnish it will soften and flatten images slightly.
Satin aqueous: A popular compromise between gloss and matte, offers a pleasing sheen and good sheet protection.
SoftTouch aqueous: A proprietary coating that is applied with a special metering roller to create a suede-like texture and extreme matte appearance.
Pencil receptive aqueous: This is a special matte aqueous coating that is designed to be pencil, ink and laser receptive.
Dry erase aqueous coating: An inexpensive high gloss alternative to lamination to make any paper suitable as dry erase marker surface.
Primer aqueous: A coating that is applied before lamination, or to difficult substrates to make them ink receptive.
UV Coatings
UV coatings are applied inline by printers or offline by finishers or converters. They are applied as a liquid, using a roller, screen or blanket, and then exposed to ultraviolet light to polymerize and harden the coating. Like aqueous coatings, UV coatings can cause certain spot colors to shift in hue. Some UV coatings may have a strong odor.
Gloss UV: Creates the highest printable overall gloss coating. Depending on the printer's equipment it can be applied to spot areas.
Matte UV: Depending on the printer's equipment it can be applied overall or just to spot areas. It is prone to fingerprinting.
Pearlescent UV: These gloss coatings include miniscule metal flecks in red, blue or silver, giving a pearlescent appearance.
Orange peel UV: A slightly raised, textured finish, gives this coating a unique tactile and visual quality that is similar in appearance to thermography.
Friday, February 3, 2012
Who is responsible for print shop color?
It is management's responsibility (with input from prepress, press room, and sales) to establish what the presswork color targets and tolerances (dot gains, standards, specifications etc.) are for the presswork - because those are marketing/business decisions. Then provide the tools (training, resources, equipment) to allow prepress and pressroom to achieve those targets.
The responsibility of prepress is to align proofing to the target established by management as well as to maintain proofing within the tolerances established by management because tolerance targets are also marketing/business decisions. Prepress must also output plates that enable the press operators to align their presswork to the proofs with the press performing in a repeatable, stable, cost-effective condition.
The responsibility of the press operator is to manage the press in such a way that the films of the appropriate inks are laid down in a manner that meets the targets and tolerances (hue, trapping, etc.) established by management and that the halftone dots on the plate are reproduced with fidelity on the various substrates (avoiding slur, doubling, etc.). Also, the press operator needs to make sure that all press-related consumables (fountain solution, inks, etc.) are within the tolerances needed to achieve the management defined targets for pressroom output.
Friday, January 20, 2012
Change “survive” to “thrive”
01 Realize that poor economic climates create opportunity. 02 Focus on your core strengths and eliminate weaknesses.
03 Lead against your competition, don’t follow.
04 Raise the bar – set the standard.
05 Treat every job you have as if it were your only job.
06 Talk to new people.
07 Question your business habits and processes.
08 If you can’t do it yourself, get someone who can do it for you.
09 Make bold moves and then tell the world about it.
10 Have fun.
Avoiding "GIGO"
‘GIGO,’ or Garbage In – Garbage Out, is one of the key barriers to the printer achieving an effective, lean, manufacturing process. This is often the result of having to accept client-provided materials that haven’t been created with the technical needs of print production in mind. Why not improve the process by hosting customer training sessions in proper document creation? Keeping your customers current with printing practices will help position you as an indispensable resource for them rather than merely a print provider. A well executed management initiated customer education program will also take the burden off of your individual sales reps to train print buyers and designers.One effective method is to contract an outside “guru” to provide the instruction. You should charge a fee to cover expenses as well as to emphasize in your customers' minds that you will be providing real value in the sessions. Then, offer to rebate the session fee on the next print order. This way the customer gets valuable training “free” and an incentive to print with you. While you, on the other hand, get better-prepared files as well as improved customer loyalty.
Saturday, December 17, 2011
Until 2012
Workin' In A Printer Wonderland - a terrific promotional video by Advocate Printing & Publishing Ltd. Pictou (and several other towns), Nova Scotia, Canada. Don't miss watching the out-takes at the end.
And then a bit of conversational artificial intellegence:
And then a bit of conversational artificial intellegence:
Saturday, November 26, 2011
"DPI" and the misuse of graphic arts terminology
The prepress and press worlds are some of the worse misusers of terminology with the all too frequent resulting confusion in sales, marketing, specification, and production. Here is one of the most misused: "DPI" (or as it is spoken of in the rest of the world: DPCM).
"DPI" - Dots Per Inch is a term used for a variety of things that properly speaking it shouldn't.
DPI - when used to describe the resolution of a computer to plate imaging device or filmsetter. E.g. "This is a 2400 dpi CtP device."
"Dots" in this case refers to the laser "Spots" of energy that expose the printing plate or film. However, while DPI, identifies the number of dots per inch - it doesn't actually describe the resolution of the device or size of the spot of energy. Instead it defines the device's "addressability." In other words, dpi tells you how many locations per inch a spot of energy can be focussed on – not the actual size of the spot of energy.
This graphic shows plate media being exposed at 2,400 dpi by six different CtP devices:
Note that they are all 2,400 dpi - that is that they all can hit the target location (address) with their beam of energy - however the exposing spots of energy are all different sizes, in this example ranging from about 2 microns on the left to about 30 microns on the right.
Resolution vs addressability is explained in more detail by clicking HERE.
DPI - when used to describe the resolution of an inkjet printer. E.g. "This inkjet proofer prints at 2880 x 1440 dpi."
In the case of an inkjet printer, the clue to this misuse of dpi to wrongly mean resolution is revealed with asymmetrical dpi specifications. So, an inkjet proofer that has the specification that says it prints at 2880 x 1440 dpi does not mean that the resolution is finer, or that the droplets of ink are finer in one direction. Instead it simply means that the paper is moved more slowly in one direction - i.e. the addressability is changed - while the physical size of the droplet of ink, and hence its resolution remains the same.
On the left a symmetrical inkjet addressability grid (600 x 600 dpi). On the right the same printer set at 1200 x 600 dpi. The addressability has changed but not the size of the cyan droplet of ink and therefore the actual resolution of the device remains the same.
In any case, the actual size of the mark the droplet of ink makes on the paper is unknown. For a 600 or 1440 "dpi" ink jet printer it most certainly is not 1/600ths or 1/1440th of an inch in size. As a result, with some inkjet printers, reference is sometimes made to "picoliters" in addition to dpi when the resolution of the device is described in the specifications. A picoliter is a unit of fluid volume. A lower minimum ink volume tends to yield a smaller minimum droplet size of ink allowing more dots of ink to be in the same area thereby yielding higher actual resolution. While picoliter is a better indicator of the relative size of the splat of ink on the paper it is still a unit of volume and not area. So it suggests a difference in resolution but doesn't actually specify it.
DPI - when used to describe the resolution of an image scanner. E.g. "This is a 600 x 2400 dpi scanner."
An image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. The resolution of Digital images is usually expressed as dots per inch or pixels per inch. As a result the resolution of scanners is often expressed in terms of dpi (and sometimes "ppi" pixels per inch). The more accurate description is "spi" which stands for "samples per inch" since scanners sample the document they are scanning.
A related issue with defining scanner resolution is that manufacturers typically refer to the scanner's interpolated resolution - which is a software upsampling algorithm method to increase the pixel density - instead of using the scanner's true optical resolution. If the scanner's dpi is asymmetrical (e.g. 600 x 2400 dpi) then the smaller number usually indicates the particular number of individual samples that are taken in the space of one linear inch while the larger number is the interpolated samples.
DPI - when used to describe the resolution of an image. E.g. "This is a 300 dpi image."
Once an image has been digitized, either via scanning or captured with a digital camera, it is in the form of a raster image made up of pixels (picture elements). In graphic arts usage the pixels are typically square in shape and 8-bits (256 grey levels) in depth per channel (greyscale = one channel, RGB = three channels, CMYK = four channels).
Because pixels are generally thought of as the smallest single component of a digital image, the more pixels that are used to represent an image, the closer the result can resemble the original.
As ppi, a.k.a. "dpi", increases so does the amount of image detail that can be rendered creating the impression of greater apparent resolution. Pixel counts can be expressed as a single number, e.g. an image at 100% reproduction size being 300 "dpi", or as in a "three-megapixel" digital camera, which has a nominal three million pixels, or as a pair of numbers, as in a "640 by 480 display", which has 640 pixels from side to side and 480 from top to bottom (as in a VGA display), and therefore has a total number of 640 × 480 = 307,200 pixels or 0.3 megapixels.
Again, the measures dots per inch (dpi) and pixels per inch (ppi) are sometimes used interchangeably, but have distinct meanings, and although dpi is often used to refer to digital image resolution the proper term is "ppi" - pixels per inch.
"DPI" - Dots Per Inch is a term used for a variety of things that properly speaking it shouldn't.
DPI - when used to describe the resolution of a computer to plate imaging device or filmsetter. E.g. "This is a 2400 dpi CtP device."
"Dots" in this case refers to the laser "Spots" of energy that expose the printing plate or film. However, while DPI, identifies the number of dots per inch - it doesn't actually describe the resolution of the device or size of the spot of energy. Instead it defines the device's "addressability." In other words, dpi tells you how many locations per inch a spot of energy can be focussed on – not the actual size of the spot of energy.
This graphic shows plate media being exposed at 2,400 dpi by six different CtP devices:
Note that they are all 2,400 dpi - that is that they all can hit the target location (address) with their beam of energy - however the exposing spots of energy are all different sizes, in this example ranging from about 2 microns on the left to about 30 microns on the right.Resolution vs addressability is explained in more detail by clicking HERE.
DPI - when used to describe the resolution of an inkjet printer. E.g. "This inkjet proofer prints at 2880 x 1440 dpi."
In the case of an inkjet printer, the clue to this misuse of dpi to wrongly mean resolution is revealed with asymmetrical dpi specifications. So, an inkjet proofer that has the specification that says it prints at 2880 x 1440 dpi does not mean that the resolution is finer, or that the droplets of ink are finer in one direction. Instead it simply means that the paper is moved more slowly in one direction - i.e. the addressability is changed - while the physical size of the droplet of ink, and hence its resolution remains the same.
In any case, the actual size of the mark the droplet of ink makes on the paper is unknown. For a 600 or 1440 "dpi" ink jet printer it most certainly is not 1/600ths or 1/1440th of an inch in size. As a result, with some inkjet printers, reference is sometimes made to "picoliters" in addition to dpi when the resolution of the device is described in the specifications. A picoliter is a unit of fluid volume. A lower minimum ink volume tends to yield a smaller minimum droplet size of ink allowing more dots of ink to be in the same area thereby yielding higher actual resolution. While picoliter is a better indicator of the relative size of the splat of ink on the paper it is still a unit of volume and not area. So it suggests a difference in resolution but doesn't actually specify it.
DPI - when used to describe the resolution of an image scanner. E.g. "This is a 600 x 2400 dpi scanner."
An image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. The resolution of Digital images is usually expressed as dots per inch or pixels per inch. As a result the resolution of scanners is often expressed in terms of dpi (and sometimes "ppi" pixels per inch). The more accurate description is "spi" which stands for "samples per inch" since scanners sample the document they are scanning.A related issue with defining scanner resolution is that manufacturers typically refer to the scanner's interpolated resolution - which is a software upsampling algorithm method to increase the pixel density - instead of using the scanner's true optical resolution. If the scanner's dpi is asymmetrical (e.g. 600 x 2400 dpi) then the smaller number usually indicates the particular number of individual samples that are taken in the space of one linear inch while the larger number is the interpolated samples.
DPI - when used to describe the resolution of an image. E.g. "This is a 300 dpi image."
Once an image has been digitized, either via scanning or captured with a digital camera, it is in the form of a raster image made up of pixels (picture elements). In graphic arts usage the pixels are typically square in shape and 8-bits (256 grey levels) in depth per channel (greyscale = one channel, RGB = three channels, CMYK = four channels).
Because pixels are generally thought of as the smallest single component of a digital image, the more pixels that are used to represent an image, the closer the result can resemble the original.
Again, the measures dots per inch (dpi) and pixels per inch (ppi) are sometimes used interchangeably, but have distinct meanings, and although dpi is often used to refer to digital image resolution the proper term is "ppi" - pixels per inch.
Wednesday, October 12, 2011
Printing Standards and Specifications
Printing standards and their associated specifications bring an independent, authoritative, and concrete basis for file preparation, proofing, presswork, and output evaluation. They reduce proofing cycles and enable faster approval processes. They also help synchronize expectations between print buyer and print provider.
I'll begin with a few definitions.
A Standard according to the International Organization for Standardization (ISO) defines a standard as:
"A document established by consensus and approved by a recognized body that provides for common and repeated use, rules, guidelines or characteristics for activities or their results, aimed at the achievement of the optimum degree of order in a given context."
A Specification is not a standard. Rather, it is a detailed description of the criteria for a piece of work. Specifications for printing can include characterization-data, ICC-profiles, PDF preflight criteria, calibration targets for the print process, etc.
A Method is usually defined as a way, technique, or process for doing something. It is a recipe.
To use a cooking analogy - a standard represents the desired final outcome, for example a cake.
The specifications describe the ingredients needed to make the cake. The method describes the steps required to make the cake. There can be many different methods to achieve the desired standard based on the specifications.
The most important standards for print production are:
• ISO 12647 which describes color for different types of presswork (sheetfed, heatset web, coldset web, etc.). Of all of the standards within the Graphic Arts, what is of most importance to most printers and print buyers are contained within the ISO 12647 family.
ISO 12647 is broken down as follows
• ISO 3664 defines lighting conditions for viewing color copies and their reproduction with either incident or transmitted light.
• ISO 15930-X (PDF/X) for data exchange in print production.
• ISO 15076 for the ICC color profile format.
• ISO 12640 for the data format from which ICC profiles are calculated.
The most important specifications for standardized print production are:
PSO Process Standard Offset printing developed by FOGRA / bvdm / ECI
This implementation of ISO 12647-2 is included with most digital proofing solutions used in Europe and is pre-configured with the UGRA FOGRA Mediawedge for verification.
Grey balance target values in PSO are done by comparing K- and CMY-patches with similar grey side by side. PSO does not contain procedures and tolerances for judging grey balance by measurement.
PSO also includes the possibility of a certification for pre-press and printing.
GRACoL/SWOP managed by IDEAlliance
These standards take their basis from ISO 12647-2 but place a higher importance on grey balance during calibration and the press run compared with the PSO. Most proofing solutions for the North American market include the needed setup to produce proofs that represent the GRACoL/SWOP target.
System Brunner
System Brunner is a standardization method for print production. It places a very strong emphasis on grey balance (in combination with TVI and Solids) for controlling and certifying the press run. System Brunner is included with some printing press manufacturer's press control solutions. It can also be combined with PSO, SWOP, or GRACoL.
There are various ISO 12647 standards according to the main types of printing methods. Here I will try and cover the essentials of just one of these - ISO 12647-2 - as an example of the type of specifications that guide printers to achieving the standard. Note that specifications do change over time, so, although the information I present is correct (as far as I know) the actual current published standards should be your guide.
ISO 12647-2 specifies a number of process parameters and their values to be applied when preparing color separations for four-color offset printing by one of the following methods: heat-set web, sheet-fed or continuous forms process printing, or proofing for one of these processes; or offset proofing for half-tone gravure. Note that the specifications are based on plates imaged in a film, not CtP, workflow.
ISO 12647-2 is
▪ directly applicable to proofing and printing processes that use color separation films as input
▪ directly applicable to proofing and printing from printing formes produced by filmless methods as long as direct analogies to film production systems are maintained
▪ applicable to proofing and printing with more than four process colors as long as direct analogies to four-color printing are maintained, such as for data and screening, for print substrates and printing parameters
▪ applicable by analogy to line screens and non-periodic (i.e. FM) screens.
ISO 12647-2 Type 1 for offset lithographic processes on gloss-coated paper specifies:
Ink: ISO 2846-1
Substrate: L* 95 a* 0 b* -2
Primary Colors (black backed): K: L* 16, a* 0, b* 0 , C: L* 54 a* -36, b* -49, M: L* 46, a* 72, b* -5, Y: L* 87, a* -6, b* 90
Secondary Colors (black backed): R (M+Y): L* 46, a* 67, b* 47 , G (C+Y): L* 49 a* -66, b* 24, B (C+M): L* 24, a* 16, b* -45, C+M+Y: L* 22, a* 0, b* 0
Solid ink densities: (informative information)*
Halftone screen: 133 lpi, 150 lpi, 175 lpi, 20 micron FM
Dot Gain/TVI: 12 -16% or 18 -22%
Grey Balance: 25%-19%-19%, 50%-40%-40%, 75%-64%- 64%
Neutral definition: substrate or equivalent tone of black
ISO profile: ISOcoated_v2_eci.icc
Characterization data: Fogra39L.txt
GRACoL 7 The General Requirements and Applications for Commercial Offset Lithography publication that is a common reference in North America and is based on ISO 12647-2 specifies:
Ink: ISO 2846-1
Substrate: ISO 12647-2
Primary Colors: ISO 12647-2*
Secondary Colors: ISO 12647-2*
Solid ink densities: Not specified
Halftone screen: 175 lpi AM round dot
Dot gain/TVI: Not specified - replaced by Neutral Print Density Curve values: @ 25% Grey: CMY .25/K .22, @ 50% Grey CMY .54/K .50, @ 75% Grey: CMY .90/K .90
Grey Balance (required): 50%-40%-40%
Neutral definition: a* 0 b* -2
ICC profile: GRACoL2006_Coated1v2.icc
Characterization data: GRACoL2006_Coated1
Some peculiarities of ISO 12647-2 and GRACoL 7
Where GRACol 7 differs from ISO 12647-2 (as per the implementation guidelines of PSO (Print Standard Offset-print)) is the method used for adjusting the mid-tones. The PSO advises adjusting the inking until the TVIs of CMY come close to their aims, while GRACol 7 would have the neutral densities of the CMY and the K grey patches brought close to the prescribed aim values regardless of the individual TVIs that result. In practice this means that each color will have a different TVI curve to achieve the neutral grey. GRACol 7 allows for deviation of primaries in order to obtain grey balance.
ISO 12647-2 includes the following chart of dot gain/TVI curves:
There are a few peculiarities with this chart. First is that there is no definition in ISO 12647 of what printing condition the letters "A" through "H" represent.** ISO 12647 does not clearly state whether these dot gain curves are intended to be tone reproduction targets or aim points or simply what you get when you use linear film to make printing plates. It appears that, because the specifications state that "direct analogies to film production systems are maintained" the intent is to use these curves as the reproduction targets. To, me, the idea of having different tone reproduction curve targets for presswork for different processes or different halftone line screens is counterproductive to standardization.
Resources:
Data set/s for profiling, separation, and proofing
ECI www.eci.org Profiles based on FOGRA data sets
FOGRA www.fogra.org Data sets that closely comply with ISO 12647
GRACoL http://www.idealliance.org
IFRA www.wan-ifra.org Profiles based on ISO 12647-3 (Newsprint)
SNAP www.naa.org SNAP profile
SWOP http://www.idealliance.org
Part 1 on this topic can be viewed by clicking HERE
*Standards documents include two broad classes of information: "normative" and "informative"
Normative elements are defined as "elements that describe the scope of the document, and which set out provisions". Provisions include requirements that convey criteria to be fulfilled if compliance with the document is to be claimed and from which no deviation is permitted.
Informative elements include supplemental information such as additional guidance, supplemental recommendations, tutorials, commentary as well as background, history, development, and relationship with other elements. Informative data is not a requirement for compliance with the standard.
**As near as I can guess (so I may be wrong), here are the printing conditions represented by the letters "A" through "H" in the ISO dot gain chart. The curves are organized from the bottom up. They sometimes do double duty.
So:
A is the curve for CMY for Coated positive plate (ISO Coated v2 and FOGRA 27, FOGRA 39 etc)
B is the curve for K for same above condition
B is also curve for CMY for Web (paper type 3)
C is the curve for K for uncoated
C is also the curve for CMY for paper type 4/5 (uncoated and uncoated yellowish)
D is curve for K for same above condition
F is the CMYK curve for 20 micron non-periodic/FM screening
E, G and H are unknown (by me anyway). I believe that "H" has been dropped from the latest ISO 12647 document so these may no longer be in force.
I'll begin with a few definitions.
A Standard according to the International Organization for Standardization (ISO) defines a standard as:
"A document established by consensus and approved by a recognized body that provides for common and repeated use, rules, guidelines or characteristics for activities or their results, aimed at the achievement of the optimum degree of order in a given context."
A Specification is not a standard. Rather, it is a detailed description of the criteria for a piece of work. Specifications for printing can include characterization-data, ICC-profiles, PDF preflight criteria, calibration targets for the print process, etc.
A Method is usually defined as a way, technique, or process for doing something. It is a recipe.
To use a cooking analogy - a standard represents the desired final outcome, for example a cake.
The specifications describe the ingredients needed to make the cake. The method describes the steps required to make the cake. There can be many different methods to achieve the desired standard based on the specifications.The most important standards for print production are:
• ISO 12647 which describes color for different types of presswork (sheetfed, heatset web, coldset web, etc.). Of all of the standards within the Graphic Arts, what is of most importance to most printers and print buyers are contained within the ISO 12647 family.
ISO 12647 is broken down as follows
ISO 12647-1 Parameters & Measurement methods• ISO 2846-1 which describes ink color and transparency.
ISO 12647-2 Offset Lithographic processes
ISO 12647-3 Coldset Offset Lithography on Newsprint
ISO 12647-4 Publication Gravure
ISO 12647-5 Screen Printing
ISO 12647-6 Flexo Printing
ISO 12647-7 Proofing process from digital data
• ISO 3664 defines lighting conditions for viewing color copies and their reproduction with either incident or transmitted light.
• ISO 15930-X (PDF/X) for data exchange in print production.
• ISO 15076 for the ICC color profile format.
• ISO 12640 for the data format from which ICC profiles are calculated.
The most important specifications for standardized print production are:
PSO Process Standard Offset printing developed by FOGRA / bvdm / ECI
This implementation of ISO 12647-2 is included with most digital proofing solutions used in Europe and is pre-configured with the UGRA FOGRA Mediawedge for verification.
Grey balance target values in PSO are done by comparing K- and CMY-patches with similar grey side by side. PSO does not contain procedures and tolerances for judging grey balance by measurement.
PSO also includes the possibility of a certification for pre-press and printing.
GRACoL/SWOP managed by IDEAlliance
These standards take their basis from ISO 12647-2 but place a higher importance on grey balance during calibration and the press run compared with the PSO. Most proofing solutions for the North American market include the needed setup to produce proofs that represent the GRACoL/SWOP target.
System Brunner
System Brunner is a standardization method for print production. It places a very strong emphasis on grey balance (in combination with TVI and Solids) for controlling and certifying the press run. System Brunner is included with some printing press manufacturer's press control solutions. It can also be combined with PSO, SWOP, or GRACoL.
There are various ISO 12647 standards according to the main types of printing methods. Here I will try and cover the essentials of just one of these - ISO 12647-2 - as an example of the type of specifications that guide printers to achieving the standard. Note that specifications do change over time, so, although the information I present is correct (as far as I know) the actual current published standards should be your guide.
ISO 12647-2 specifies a number of process parameters and their values to be applied when preparing color separations for four-color offset printing by one of the following methods: heat-set web, sheet-fed or continuous forms process printing, or proofing for one of these processes; or offset proofing for half-tone gravure. Note that the specifications are based on plates imaged in a film, not CtP, workflow.ISO 12647-2 is
▪ directly applicable to proofing and printing processes that use color separation films as input
▪ directly applicable to proofing and printing from printing formes produced by filmless methods as long as direct analogies to film production systems are maintained
▪ applicable to proofing and printing with more than four process colors as long as direct analogies to four-color printing are maintained, such as for data and screening, for print substrates and printing parameters
▪ applicable by analogy to line screens and non-periodic (i.e. FM) screens.
ISO 12647-2 Type 1 for offset lithographic processes on gloss-coated paper specifies:
Ink: ISO 2846-1
Substrate: L* 95 a* 0 b* -2
Primary Colors (black backed): K: L* 16, a* 0, b* 0 , C: L* 54 a* -36, b* -49, M: L* 46, a* 72, b* -5, Y: L* 87, a* -6, b* 90
Secondary Colors (black backed): R (M+Y): L* 46, a* 67, b* 47 , G (C+Y): L* 49 a* -66, b* 24, B (C+M): L* 24, a* 16, b* -45, C+M+Y: L* 22, a* 0, b* 0
Solid ink densities: (informative information)*
Halftone screen: 133 lpi, 150 lpi, 175 lpi, 20 micron FM
Dot Gain/TVI: 12 -16% or 18 -22%
Grey Balance: 25%-19%-19%, 50%-40%-40%, 75%-64%- 64%
Neutral definition: substrate or equivalent tone of black
ISO profile: ISOcoated_v2_eci.icc
Characterization data: Fogra39L.txt
GRACoL 7 The General Requirements and Applications for Commercial Offset Lithography publication that is a common reference in North America and is based on ISO 12647-2 specifies:
Ink: ISO 2846-1
Substrate: ISO 12647-2
Primary Colors: ISO 12647-2*
Secondary Colors: ISO 12647-2*
Solid ink densities: Not specified
Halftone screen: 175 lpi AM round dot
Dot gain/TVI: Not specified - replaced by Neutral Print Density Curve values: @ 25% Grey: CMY .25/K .22, @ 50% Grey CMY .54/K .50, @ 75% Grey: CMY .90/K .90
Grey Balance (required): 50%-40%-40%
Neutral definition: a* 0 b* -2
ICC profile: GRACoL2006_Coated1v2.icc
Characterization data: GRACoL2006_Coated1
Some peculiarities of ISO 12647-2 and GRACoL 7
Where GRACol 7 differs from ISO 12647-2 (as per the implementation guidelines of PSO (Print Standard Offset-print)) is the method used for adjusting the mid-tones. The PSO advises adjusting the inking until the TVIs of CMY come close to their aims, while GRACol 7 would have the neutral densities of the CMY and the K grey patches brought close to the prescribed aim values regardless of the individual TVIs that result. In practice this means that each color will have a different TVI curve to achieve the neutral grey. GRACol 7 allows for deviation of primaries in order to obtain grey balance.
ISO 12647-2 includes the following chart of dot gain/TVI curves:
There are a few peculiarities with this chart. First is that there is no definition in ISO 12647 of what printing condition the letters "A" through "H" represent.** ISO 12647 does not clearly state whether these dot gain curves are intended to be tone reproduction targets or aim points or simply what you get when you use linear film to make printing plates. It appears that, because the specifications state that "direct analogies to film production systems are maintained" the intent is to use these curves as the reproduction targets. To, me, the idea of having different tone reproduction curve targets for presswork for different processes or different halftone line screens is counterproductive to standardization. Resources:
Data set/s for profiling, separation, and proofing
ECI www.eci.org Profiles based on FOGRA data sets
FOGRA www.fogra.org Data sets that closely comply with ISO 12647
GRACoL http://www.idealliance.org
IFRA www.wan-ifra.org Profiles based on ISO 12647-3 (Newsprint)
SNAP www.naa.org SNAP profile
SWOP http://www.idealliance.org
Part 1 on this topic can be viewed by clicking HERE
*Standards documents include two broad classes of information: "normative" and "informative"
Normative elements are defined as "elements that describe the scope of the document, and which set out provisions". Provisions include requirements that convey criteria to be fulfilled if compliance with the document is to be claimed and from which no deviation is permitted.
Informative elements include supplemental information such as additional guidance, supplemental recommendations, tutorials, commentary as well as background, history, development, and relationship with other elements. Informative data is not a requirement for compliance with the standard.
**As near as I can guess (so I may be wrong), here are the printing conditions represented by the letters "A" through "H" in the ISO dot gain chart. The curves are organized from the bottom up. They sometimes do double duty.
So:
A is the curve for CMY for Coated positive plate (ISO Coated v2 and FOGRA 27, FOGRA 39 etc)
B is the curve for K for same above condition
B is also curve for CMY for Web (paper type 3)
C is the curve for K for uncoated
C is also the curve for CMY for paper type 4/5 (uncoated and uncoated yellowish)
D is curve for K for same above condition
F is the CMYK curve for 20 micron non-periodic/FM screening
E, G and H are unknown (by me anyway). I believe that "H" has been dropped from the latest ISO 12647 document so these may no longer be in force.
Thursday, September 29, 2011
Standardize your print process
A standardized print manufacturing process is critical for achieving effective press to proof color alignment, short press makereadies, and minimal wastage of time and materials.The five basic steps are:
1. Choose the appropriate standard and/or specification target for the presswork.
Management's responsibility (with input from prepress, press room, and sales) is to establish what the targets and tolerances (dot gains, standards, specifications etc.) are for the presswork - because those are marketing/business decisions. Then management must provide the tools to allow prepress and pressroom to achieve those targets. That target then drives the complete print production process and determines the selection of all of the components (proofs, press calibration, inks, paper, etc.) needed to hit the target. Worldwide the most adopted standard for printing is ISO 12647-x. The various ISO 12647 standards provide specifications for data, proofs, inks, paper and press calibration. In North America GRACoL and SWOP specifications are largely based on ISO 12647-2 and ISO 12647-3 respectively.
2. Clearly communicate with print customers about requirements for data/file submission.
This includes items such as whether files should adhere to industry specifications such as SNAP or face rejection. It may include items such as whether native application files are acceptable or only PDFs, what resolution and color mode that images need to be, what minimum text size is acceptable, etc., etc.
3. Implementation of standardized proofing.
In-house proofing must be set up to the same standard and/or specification target for the presswork (i.e. ISO 12647-x, SWOP, etc.). If print customers will be providing proofs for the pressroom then the printer has to communicate that customer-submitted proofs must adhere to the appropriate standard. All proofs must include a color control strip so that they can be verified for conformance to the target standard/specification. There should be virtually no difference in appearance between a customer-supplied proof and one done by the printer in-house. It should also be made clear that the printer's in-house proof is the final proof.
4. Optimize prepress.
The responsibility of prepress is to align proofing to the target established by management as well as to maintain proofing within the tolerances established by management. Prepress must also output plates that enable the press operators to align their presswork to the proofs with the press performing in a repeatable, stable condition. Prepress should have well defined procedures for ensuring that platemaking and the resulting plates are consistent and within tolerance.
5. Optimize press performance.
The responsibility of the press operator(s) is to manage the press in such a way that the the films of the appropriate inks (as defined by the chosen specifications) are laid down in a manner that meets the targets and tolerances (hue, trapping, etc.) established by management and that the halftone dots on the plate are reproduced with fidelity on the various substrates (slur, doubling, etc.). Also, the press operator needs to make sure that all press-related consumables (fountain solution, inks, etc.) are within the tolerances needed to achieve the management defined targets for pressroom output.
Saturday, July 30, 2011
What the press operator is scrutinizing
It's the stereotypical image of a press operator - bent over the presswork and examining it under a loupe. People attending a press approval often wonder what the press operator is examining so closely. In fact there's a great deal of information that the press operator can determine from a close up view of the press work.The first thing that's checked is registration.
Next is halftone dot formation.
Monday, March 14, 2011
Competition - A lesson from the 2002 Olympics
Competition is at the core of most business ventures - including printing. Sometimes a lesson for success can be learned from other competitive endevors as in this one provided by Steven Bradbury at the 2002 Olympics.
Steven Bradbury (the tall guy) competing at the 2002 Olympics. Click the "Play" arrow to watch this short video.
Proof that it pays to never give up, regardless of how you may be viewing the competition from your current vantage point.
Steven Bradbury (the tall guy) competing at the 2002 Olympics. Click the "Play" arrow to watch this short video.
Proof that it pays to never give up, regardless of how you may be viewing the competition from your current vantage point.
Thursday, January 13, 2011
A Manifesto for Manufacturers
The Unwritten Laws of Engineering by California engineer W. Julian King was first published in 1944 as three articles in Mechanical Engineering magazine. It has been in print as a book ever since. Recent editions, including a trade version, The Unwritten Laws of Business, have revisions and additions by James G. Skakoon. The Unwritten Laws are not about engineering, but about behavior and contain sound advice for any business and its employees. A Manifesto for Manufacturers
HOWEVER MENIAL and trivial your early assignments may appear, give them your best efforts.
DEMONSTRATE the ability to get things done.
DEVELOP a “Let’s go see!” attitude.
DON’T be timid – speak up – express yourself and promote your ideas
STRIVE for conciseness and clarity in oral or written reports; be extremely careful of the accuracy of your statements.
ONE of the first things you owe your supervisor is to keep them informed of all significant developments.
DO NOT overlook the steadfast truth that your direct supervisor is your “boss”.
BE as particular as you can in the selection of your supervisor.
WHENEVER you are asked by your manager to do something, you are expected to do exactly that.
CULTIVATE the habit of seeking other peoples’ opinions and recommendations.
PROMISES, schedules, and estimates are necessary and important instruments in a well-ordered business.
IN DEALING with customers and outsiders, remember that you represent the company, ostensibly with full responsibility and authority.
DO NOT try to do it all yourself.
EVERY manager must know what goes on in their domain.
CULTIVATE the habit of “boiling matters down” to their simplest terms.
CULTIVATE the habit of making brisk, clean-cut decisions.
LEARN PROJECT MANAGEMENT skills and techniques, then apply them to the activities that you manage.
MAKE SURE that everyone – managers and subordinates – has been assigned definite positions and responsibilities within the organisation.
MAKE SURE that all activities and all individuals are supervised by someone competent in the subject matter involved.
NEVER MISREPRESENT a subordinate’s performance during performance appraisals.
MAKE it unquestionably clear what is expected of employees.
YOU OWE it to your subordinates to keep them properly informed.
NEVER MISS a chance to commend or reward subordinates for a job well done.
ALWAYS ACCEPT full responsibility for your group and the individuals in it.
ONE OF the most valuable personal traits is the ability to get along with all kinds of people.
NEVER UNDERESTIMATE the extent of your professional responsibility and personal liability.
LET ETHICAL BEHAVIOR govern your actions and those of your company.
BE AWARE of the effect that your personal appearance and behavior have on others and, in turn, on you.
BEWARE of what you commit to writing and of who will read it.
ANALYSE yourself and your subordinates.
MAINTAIN your employability as well as that of your subordinates.
Thanks to blog reader "Alois Senefelder" who suggested this Manifesto be posted in Quality in Print.
Monday, December 13, 2010
TRONitized - the influence of TRON on graphic art (well mine anyway)
In 1982 Disney released the seminal movie TRON, a film which wasn't a large commercial success but did become a cult favorite.
It was a very different world back then. Mobile phones were the size of briefcases and very few people had access to a "real" computer but settled instead for machines like the Commodore VIC-20 and the Atari 400/800. If you didn't know what a spreadsheet or word processor was, then at least you play video games on the device.
TRON was the first film to really expose people to the potential of computer graphics and at the time had a big impact on my graphic design and illustration work.
State of the art computer graphics when TRON was released.
What impressed most people about TRON were the glow effects. That is what they thought were the computer effects. But in reality the glow effects were done with old-fashioned non-digital methods which I was able to recreate in my basement photo studio.
Recreating the TRON glow: from left bottom layer to right top layer: lith film negative, 1/4" thick frosted glass, colored acetate gel, lith film positive.
Photographing all the layers in register from directly overhead using an old vegetable crate turned into a lightbox created the glow "computer graphic" effect.
If needed, a second exposure (with a lith film mask) using a special lens filter (sometimes homemade using nylon stockings) would add a little sparkle.
It was a vary tedious process as I first had to plan then create the artwork. I used 2 1/4" x 2 3/4" film in a special holder on my 4"x5" view camera. Each image required several exposures depending on the complexity of the final effect. There was no way to preview how the final image would look, so the exposed film would be taken for processing late at night so that it would be ready for viewing the next morning. If anything was wrong, any small error in registration, or exposure, or a spec of dust in the image meant that it would have to be reshot.
Despite the complexity of the process, my illustration style based on this technique:
Was used for corporate brochures:
As well as the early promotions for Vancouver's 1986 World's Fair:
And product brochures:
Magazine covers:
And various editorial illustration applications:
Universally, art directors thought that I was a real wizard of computer graphics and was able to give them the high-tech look they were after - even though, secretly, all I used was hand drawn art mixed in with some old-school photographic film trickery.
TRON: Legacy will be released to theaters December 17, 2010.
It was a very different world back then. Mobile phones were the size of briefcases and very few people had access to a "real" computer but settled instead for machines like the Commodore VIC-20 and the Atari 400/800. If you didn't know what a spreadsheet or word processor was, then at least you play video games on the device.TRON was the first film to really expose people to the potential of computer graphics and at the time had a big impact on my graphic design and illustration work.
What impressed most people about TRON were the glow effects. That is what they thought were the computer effects. But in reality the glow effects were done with old-fashioned non-digital methods which I was able to recreate in my basement photo studio.
It was a vary tedious process as I first had to plan then create the artwork. I used 2 1/4" x 2 3/4" film in a special holder on my 4"x5" view camera. Each image required several exposures depending on the complexity of the final effect. There was no way to preview how the final image would look, so the exposed film would be taken for processing late at night so that it would be ready for viewing the next morning. If anything was wrong, any small error in registration, or exposure, or a spec of dust in the image meant that it would have to be reshot.
Despite the complexity of the process, my illustration style based on this technique:
Was used for corporate brochures:
As well as the early promotions for Vancouver's 1986 World's Fair:
And product brochures:
Magazine covers:
And various editorial illustration applications:
Universally, art directors thought that I was a real wizard of computer graphics and was able to give them the high-tech look they were after - even though, secretly, all I used was hand drawn art mixed in with some old-school photographic film trickery.
TRON: Legacy will be released to theaters December 17, 2010.
Thursday, September 16, 2010
The right loupe for the job
Spend any time in a printshop and you'll quickly discover that press operators, and even print buyers, depend on their loupes to help inform them about the quality of plates, proofs, and presswork.
This is a quick guide to help you choose the correct instrument for your needs. Beside each type of loupe/microscope is an image to approximate the view through that instrument. Keep in mind that all loupes and microscopes have limitations based on the laws of optics and that prices can vary widely. That is why having more than one instrument is usually best. In general the higher the magnification the smaller the field of view, the shallower the depth of view, and the closer the instrument must be to the subject. A single lens is satisfactory for low power loupes but higher power ones require two or more lens elements for improved resolution and correction of chromatic aberrations, distortion, and improved flatness of field (i.e. the entire viewed area appears in focus rather than just a small area in the center of the view).
Wide field comparator - 2x-6x ~ $50-$100
As its name implies, comparator loupes are typically used to compare two items, e.g. proof to press sheet, different paper surfaces, halftone screening methods, proof reading, etc.
Pros: Long eye relief coupled with a wide, flat field of view allows it to be shared by more than one viewer at a time without moving the loupe. Cut-away base allows room for touch-ups or mechanical changes to the item under inspection. Can be used to evaluate large scale issues such as halftone rosette structures and paper/ink mottle.
Cons: Rather limited applications in prepress/press relative to the cost. Low magnification does not reveal halftone quality issues.
Linen tester/folding loupe - 2x-10x ~ $25
This is the iconic press operator's loupe.
Use: Good for checking registration and macro imaging problems like rosette structure integrity and mottle.
Pros: Inexpensive, portable, easily available.
Cons: Low magnification does not reveal halftone quality issues. No focus adjustment.
Folding loupe (a.k.a. Hastings loupe, Hastings Triplet, Swing Loupe) - 10x-25x ~ $70
This is arguably the type of loupe actually most used by press operators. Highly recommended as a good all 'round basic loupe.
Use: Good for checking registration and macro imaging problems like rosette structure integrity and mottle. Higher magnification begins to identify issues such as slur and doubling.
Pros: Relatively inexpensive, portable.
Cons: None.
Rigid loupe - 10x-75x ~ $650
This magnifier is sometimes used in the press room but is more often used by a Quality Assurance Manager. Very flexible in that it can be customized with different lens options.
Use: Good for checking registration and with higher magnification, to identify issues such as slur and doubling.
Pros: Optional lenses can customize unit for specific shop needs. May come with color filters to enhance the visibility of dot structures. Built-in light.
Cons: Very expensive.
Pen microscope - 25x-100x ~ $100
This magnifier can be used in the press room and prepress. 50X is most popular - 75-100x is very good for checking FM screening. An excellent all 'round high magnification tool.
Use: Very good for identifying imaging issues such as slur and doubling.
Pros: Convenient pocket size. Can be focused by manually tilting it but can be difficult to hold steady.
Cons: Expensive.
Lab-type microscope - 25x-100x ~ $250
This magnifier tends to be more often used by a Quality Assurance Manager in a lab setting. 75-100x is most popular and very good for checking FM screening.
Use: Very good for identifying imaging issues such as slur and doubling.
Pros: Built-in measuring reticle scale is helpful in analyzing halftone structures.
Cons: Expensive. Typically produces an inverted view.
Digital video microscope - 20x-200x ~ $125
This magnifier tends to be more often used by a Quality Assurance Manager in a lab setting. 200x is most popular and is ideal for checking FM screening as well as detailed analysis of halftone issues. A must-have for any print/prepress shop.
Use: Excellent for identifying imaging issues such as slur and doubling and analyzing halftone reproduction issues. Ability to take photos and videos of halftones and other micro-features enables better record keeping as well as remote diagnostics. Build-in light helps with image quality. Software may be included for more detailed image analysis.
Pros: Still and video image capture. High magnification. Ability to process images with image analysis software. Ability to document and share image capture. Relatively inexpensive.
Cons: Must be tethered to a computer.
Where to buy
Shops that sell binoculars/telescopes, collectibles/stamps, and hobbyist supplies will also carry a selection of loupes and microscopes.
If your local shops can not source what you need - online sources include: http://www.edmundoptics.com, http://www.betascreen.com, http://www.amazon.com, http://www.ebay.com/
Addendum
A reader, "Otherthoughts" described some of his experiences with the lab-type and pen microscopes.
"Regarding inversion and some background about why this was/is important to me.
I used a 25x scope like this for inspecting things a little closer during my press-man/press-room days.
Mine had a metric measuring reticle in it. Sometimes I would break this scope out and measure how far off the register marks were and then I would input the distance corrections into the press control unit. On the next pull, the marks would be almost perfectly registered. I only did this when the register marks were way off and/or I wanted to impress someone. The main reason I didn't use the scope more often as a Pressman, was because of it's inverted view. It's a pain to keep mumbling to yourself "left is right and up is down" when using this type of scope.
Without exception, every single stand/pen microscope that I've ever looked through at a trade show or that a vendor has shown to me in the press-room, has produced an inverted view as well. I always wanted to buy a right reading stand microscope of 25x or more, but I've never found one.
I know things have changed quite a bit since my days in the field. Nonetheless, there will still be directional components to the things that will be evaluated using these microscopes, e.g. slur, doubling, etc. and you will likely still have to remind yourself that "left is right and up is down" while evaluating their cause, meaning and remedies."
Thanks for the contribution Otherthoughts!
This is a quick guide to help you choose the correct instrument for your needs. Beside each type of loupe/microscope is an image to approximate the view through that instrument. Keep in mind that all loupes and microscopes have limitations based on the laws of optics and that prices can vary widely. That is why having more than one instrument is usually best. In general the higher the magnification the smaller the field of view, the shallower the depth of view, and the closer the instrument must be to the subject. A single lens is satisfactory for low power loupes but higher power ones require two or more lens elements for improved resolution and correction of chromatic aberrations, distortion, and improved flatness of field (i.e. the entire viewed area appears in focus rather than just a small area in the center of the view).Wide field comparator - 2x-6x ~ $50-$100
As its name implies, comparator loupes are typically used to compare two items, e.g. proof to press sheet, different paper surfaces, halftone screening methods, proof reading, etc.Pros: Long eye relief coupled with a wide, flat field of view allows it to be shared by more than one viewer at a time without moving the loupe. Cut-away base allows room for touch-ups or mechanical changes to the item under inspection. Can be used to evaluate large scale issues such as halftone rosette structures and paper/ink mottle.
Cons: Rather limited applications in prepress/press relative to the cost. Low magnification does not reveal halftone quality issues.
Linen tester/folding loupe - 2x-10x ~ $25
This is the iconic press operator's loupe.Use: Good for checking registration and macro imaging problems like rosette structure integrity and mottle.
Pros: Inexpensive, portable, easily available.
Cons: Low magnification does not reveal halftone quality issues. No focus adjustment.
Folding loupe (a.k.a. Hastings loupe, Hastings Triplet, Swing Loupe) - 10x-25x ~ $70
This is arguably the type of loupe actually most used by press operators. Highly recommended as a good all 'round basic loupe.Use: Good for checking registration and macro imaging problems like rosette structure integrity and mottle. Higher magnification begins to identify issues such as slur and doubling.
Pros: Relatively inexpensive, portable.
Cons: None.
Rigid loupe - 10x-75x ~ $650
This magnifier is sometimes used in the press room but is more often used by a Quality Assurance Manager. Very flexible in that it can be customized with different lens options.Use: Good for checking registration and with higher magnification, to identify issues such as slur and doubling.
Pros: Optional lenses can customize unit for specific shop needs. May come with color filters to enhance the visibility of dot structures. Built-in light.
Cons: Very expensive.
Pen microscope - 25x-100x ~ $100
This magnifier can be used in the press room and prepress. 50X is most popular - 75-100x is very good for checking FM screening. An excellent all 'round high magnification tool.Use: Very good for identifying imaging issues such as slur and doubling.
Pros: Convenient pocket size. Can be focused by manually tilting it but can be difficult to hold steady.
Cons: Expensive.
Lab-type microscope - 25x-100x ~ $250
This magnifier tends to be more often used by a Quality Assurance Manager in a lab setting. 75-100x is most popular and very good for checking FM screening.Use: Very good for identifying imaging issues such as slur and doubling.
Pros: Built-in measuring reticle scale is helpful in analyzing halftone structures.
Cons: Expensive. Typically produces an inverted view.
Digital video microscope - 20x-200x ~ $125
This magnifier tends to be more often used by a Quality Assurance Manager in a lab setting. 200x is most popular and is ideal for checking FM screening as well as detailed analysis of halftone issues. A must-have for any print/prepress shop.Use: Excellent for identifying imaging issues such as slur and doubling and analyzing halftone reproduction issues. Ability to take photos and videos of halftones and other micro-features enables better record keeping as well as remote diagnostics. Build-in light helps with image quality. Software may be included for more detailed image analysis.
Pros: Still and video image capture. High magnification. Ability to process images with image analysis software. Ability to document and share image capture. Relatively inexpensive.
Cons: Must be tethered to a computer.
Where to buy
Shops that sell binoculars/telescopes, collectibles/stamps, and hobbyist supplies will also carry a selection of loupes and microscopes.
If your local shops can not source what you need - online sources include: http://www.edmundoptics.com, http://www.betascreen.com, http://www.amazon.com, http://www.ebay.com/
Addendum
A reader, "Otherthoughts" described some of his experiences with the lab-type and pen microscopes.
"Regarding inversion and some background about why this was/is important to me.
I used a 25x scope like this for inspecting things a little closer during my press-man/press-room days.
Mine had a metric measuring reticle in it. Sometimes I would break this scope out and measure how far off the register marks were and then I would input the distance corrections into the press control unit. On the next pull, the marks would be almost perfectly registered. I only did this when the register marks were way off and/or I wanted to impress someone. The main reason I didn't use the scope more often as a Pressman, was because of it's inverted view. It's a pain to keep mumbling to yourself "left is right and up is down" when using this type of scope.Without exception, every single stand/pen microscope that I've ever looked through at a trade show or that a vendor has shown to me in the press-room, has produced an inverted view as well. I always wanted to buy a right reading stand microscope of 25x or more, but I've never found one.
I know things have changed quite a bit since my days in the field. Nonetheless, there will still be directional components to the things that will be evaluated using these microscopes, e.g. slur, doubling, etc. and you will likely still have to remind yourself that "left is right and up is down" while evaluating their cause, meaning and remedies."
Thanks for the contribution Otherthoughts!
Wednesday, August 25, 2010
Every letter tells a story - print problems revealed in type reproduction.
Spend even a small amount of time in a printshop and you'll quickly realize how much effort press operators put into scrutinizing their presswork through a loupe. The two things they're typically looking for are clear centered rosettes - this tells them that the presswork is in register – and print problems revealed by how well individual letters of type are reproduced in print.Here's how type printed offset reveals problems:
Normal ink transfer - no apparent problems.
Doubling
A ghost image appears just behind the primary graphic causing an increase in dot gain. More information about doubling HERESlur
A smeared ghost image appears just behind the primary graphic. More information about slur HEREOver emulsified (a.k.a. emulsified, water logged)
Ink is designed to accept a small amount of water (fountain solution) on press. Too much water appears as tiny droplets in solid areas and reduces gamut, image sharpness, contrast, and increases dot gain.Tailing (a.k.a. misting, slinging)
Too high a solid ink density or ink that's too "long" can cause thin "tails" of ink strands to appear extending behind the primary image causing a loss of sharpness, contrast and an increase in dot gain.Picking (a.k.a. pinholing)
Small white specks appear in solids. This usually results because the ink tack is too high or there is not enough impression cylinder pressure ("squeeze").Ink breakdown
On press, fountain solution acts like a solvent. If it is too aggressive or acidic it can break down the ink that forms the image resulting in presswork that appears muddy and/or "soft." It also reduces total gamut because it reduces overprint trapping efficiency.
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