How to print from Apple's iPad

"Nature finds a way."Print prevails with this innovative technical breakthrough achieved by the folks HERE.

A different side of Steve Jobs

Steve Jobs is much in the news these days with the iPad and iAd. His "reality distortion field" when introducing new products is the envy of many marketeers. This though is a different side of the man. From www.ted.com, Steve Jobs, CEO and co-founder of Apple and Pixar, urges us in this 14 minute inspirational talk at his Stanford University commencement speech in 2005, to pursue our dreams and see the opportunities in life's setbacks - including death itself.
Click play arrow (and maybe wiggle the play head), to view the video.

Finding a "Quality" printshop

Most printers would consider themselves to be "quality" printers. A very few actually put it in their business name. A quick search on Google and a bit of help from street view quickly revealed these boldly self described quality printing establishments. Is there a quality printer in your location?

How to calculate halftone dot sizes in microns

When working with screen rulings, particularly those above 200 LPI or FM screening, you may need to know the size of dots in microns. This is to make sure that the plates, plate imaging system, press, and ink pigments are all capable of delivering the minimum printing dots through the process. For example, if the dot size is 10 microns but the ink pigment size is 25 microns there may not be enough dot surface area for the pigment to stick to and hence that tone will be dropped out on press. Or, if the screen calls for a 10 micron dot but the plate can only hold a 20 micron dot then, again, that tone will be lost or have to be compensated for by employing hybrid screening techniques.

Dot diameter in microns can be calculated using the following formula.
Where:
D = Dot area in percent (e.g. 1% dot equals .01)
F = Screen frequency in lines per millimeter (LPM)

To convert the screen frequency from lines per inch use the following formula (2,540 dpi device on left and 2,400 dpi device on right):
While this formula is not absolutely exact, it gives a close enough approximation for most practical purposes.

A few things to keep in mind about halftone dot size. The formula applies to the size of dot that is generated by the halftone screening algorithms in the RIP that will be sent to the imaging device. It does not calculate the size of the dot that appears in the final presswork which may have been affected by dot gain or loss. Also, a RIP will only image full individual pixels to form a halftone dot. So, in the case of a 2,540 dpi device, each pixel is 10 microns in size (10.6 microns for a 2,400 dpi device). Therefore, if, for example, the formula says that the final diameter of the dot is 15 microns what will happen is that the RIP will alternate between 1 pixel dots (10 micron) and 2 pixel dots (20 micron) which results in an effective 15 micron dot average for that tone value. You can see that happening by watching the dot formation in the lighter tones at the start of the video located HERE.

Below is a quick reference comparison chart showing the dot diameters for tone values of 1% and 2% for various screen rulings from 10 LPI to 400 LPI on a 2,540 dpi platesetter.Highlighted areas are where the required dot is smaller than a single pixel at the device's resolution and therefore will not be imaged.

Write it down. Document it. Now.

Production mistakes happen. It's part of the business. Hopefully they get corrected and the print shop moves on. What's frustrating is when the same mistake happens again. One good way to avoid making the same mistake twice is to document it in a journal. Two of my old "print experience journals" filled with technical production notes, test results, samples, and odds and sods of print-related information.
A "print experience" journal can be used to document mistakes and how they were corrected, prepress/press tests and results, samples of interesting print effects, and technical bits and pieces of information. Some print shops create a database, hosted on a server, of this type of information that CSRs, sales people, estimators, and production people can both access and add to.

Documenting production experience in an accessible form, like a journal or database, helps the shop learn from its past and reduce the chance of making the same mistake twice. They can preserve the knowledge inside the company even when key employees leave the business.

Tolerancing color in presswork by eye

Once the press operator has achieved their solid ink density targets during make ready, they typically will do a visual examination to compare presswork color to proof to evaluate the closeness of the match. They will also do visual comparisons during the run to check the consistency of the match through the press run. Print buyers typically also do the same thing - relying on their eye for color to verify the match and consistency.
For most people in the graphic arts, the eye is the final arbitrator on the quality and consistency of presswork - however, this method has some limitations caused by the fact that the eye is part of a very tricky instrument: the human brain. For example, look carefully at this graphic containing light green and light blue swirls:
Light green and light blue?

Actually there are no light blue swirls, What you see as light blue is actually the same color as the green ones. They are both R 0, G 255, B 151. Cutting out a section of the "light blue" swirls and lining them up with the light green ones proves they are indeed the same color.This illusion is so strong that you might have to down load the image into PhotoShop and confirm it for yourself.

There are several characteristics of our eye/brains that can play tricks on our perception. Being aware of them will help you more clearly understand how your color perception can be mislead and hopefully provide a clearer view as to what you are actually seeing.

1) The eye/brain auto-white balances. The eye/brain selects an area that it "knows" is white - forces it to appear white and balances other colors accordingly. This is the trick that allows us to see a white paper as white with surrounding colors being natural under a variety of different colored lighting situations. This often causes problems with monitor proofs where an image should be "white" i.e. should result in no halftone dots in the presswork, but in fact has grey or even a color cast in it that results in dots being printed. The eye/brain sees the area as white when in fact it is not.

2) The eye/brain has no color memory. Not only does the eye/brain auto-white balance, it also rebalances color whenever you look from one object to another. This makes comparing two colors that are separated, by even a small distance, impossible. For example, in the below image, the press operator cannot effectively compare color between the image on his soft-proof with the color on his press sheet.
The only way to compare two colors is by cutting through one sample and overlaying it on a reference (e.g. cut press sheet over proof) like this:If the color aligns across the cut then you have a match.

3) The eye/brain cannot judge variation consistently. In order to tolerance acceptable color variation, for example custom/brand colors, you need to have a reference high/low density guide that provides an example of the two extremes that the color must fall within. Providing a swatch guide with holes through it as in this example:allows users to place the swatch over the press sheet to more easily confirm the color match as well as whether it falls between the two acceptable extremes.

4) The eye/brain's perception of color is influenced by the size of the area of color. This is one of the reasons that the paint color selected from a small paint chip seldom appears the same as the color once it's painted on the wall. The same issue happens when selecting a spot or brand color from a swatchbook. Always try to get a reference chip, draw down, or previously printed sample, that is as large as possible.

5) The eye/brain's perception of color difference is not uniform for all colors. It is difficult for the eye/brain to see differences in highly saturated colors. However, a small degree of variation is easily seen when colors are near neutral. Variations in the green part of the spectrum are more easily noticed than the same degree of variation in the red part of the spectrum.

The Wayback View - Print Ephemera

"Ephemera: transitory, transient, fleeting, passing, short-lived, momentary, brief, short; temporary, impermanent."

Just a very few examples of print ephemera - items that usually do not survive the passage of time. Rare because, being of little apparent value, very few care to preserve them.

A lenticular letter opener promotes this 1950s printer:
Printer invoices are some of the least preserved aspects of print.

From 1894:
From 1905:
From 1913. Note the two hours of customer alterations resulting in a $1.50 extra charge. Also, the invoice was made just after Christmas and was paid just over thirty days later. Impressive! The fact that this printer is still in business - outstanding!
From 1929:
From 1933. Think short run printing is the latest thing? This invoice to the Catholic Records Society from John Whitehead & Son Limited is for just 25 leaflets.
Print sales representative business cards are also quite rare.

From the 1870s - what a great address: "Between High and Purchase Streets." Partner Clifford displays his complete first name but partner Crawford is only allowed an enigmatic "W." And their unique capability? "First-Class Blank Books a Speciality." In other words, their best printing is no printing at all!
A more conventional business card from the turn of the century:

Even vendor material, although often inspirational, was not likely to be preserved:
If you have any examples of print ephemera to share please send them to me via pritchardgordon (@) gmail (dot) com

Tolerancing color in presswork using solid ink density

Background information - ink film thickness & solid ink density

Offset printing presses are designed to lay down a film of ink, in the presence of water, onto a substrate - usually paper. The ink forms the image while the "water," more accurately fountain solution," prevents the non-image area on the printing plate from accepting ink. For the process to work, there needs to be a critical ink/water balance with the goal of having an ink film thickness between one micron.

If the ink film thickness is too great, the result can be "ink tailing/misting." In addition, the non-image background may take on ink resulting in "catch-up" (sometimes mistaken for "scumming"):
On the other hand, if the ink film thickness is too thin, the result can be a breakdown of the ink on the sheet causing low contrast, loss of sharpness, and mottle:
So, from a color tolerancing point of view, because the function of ink is to filter light and allow us to see color and because its thickness also effects the integrity of the printing process - ink film thickness on the sheet becomes an important metric to measure and tolerance in presswork.Top: CMYK at high ink film thickness/solid ink density.
Bottom: CMYK at low ink film thickness/solid ink density.
There is no practical way to directly measure the ink film thickness on a press sheet. However, there is an indirect way and that is to measure the solid ink density (SID) using an instrument called a densitometer.

Color tolerancing through densitometry

Measuring SIDs in the solid ink patches in the color bar with a densitometer does not actually provide information about the color being printed. However, because it indirectly provides information about ink film thickness (which impacts color and tone reproduction) SID values are valuable for process control and defining variation during a press run where the instrument, ink, and substrate remain the same.North American (Status-T) high-low specifications for acceptable SID variations measured with ink dry.
Top: Commercial sheetfed, Middle: Magazine/heatset web,
Bottom: Newsprint/coldset web.
From a color point of view, the assumption is that all three chromatic colors vary in the same direction and therefore remain in relative balance. When that happens there is a shift in color saturation (higher SIDs = higher saturation) as well as tone reproduction (higher SIDs = higher dot gain/TVI). If one color, e.g. Cyan, is at the maximum low point while another color, e.g. Magenta, is at the maximum high then the result may be a visible color bias in the presswork.
Typical SID variation in presswork graphed by measuring color bar patches every 10 sheets through the press run.
While a densitometer can also be used to monitor variations in non-process, i.e. spot/Pantone colors, usually a printed sample of the target color, including a high/low density tolerance reference, is used instead since this helps both print specifier and supplier visualize the acceptable range of color change as SIDs naturally vary during the press run.Checking for spot color variation
Addendum: Densitometer set up - "Status" condition

Densitometers are set by their manufacturers to an industry defined "Status" which defines the total response of the instrument including light source, optics, filtering, and receptor for given wavelength. The primary responses for the print business are "Status E" and "Status T" (ANSI PH2.18 and DIN 16536). In addition, densitometers are available with or without polarizing filters. Dry ink density readings from polarizing and unpolarized densitometers as well as those set to Status E vs Status T will not agree. Typically European instruments are set to Status E and use polarizing filters while North American instruments are set to Status T and do not use polarizing filters.

The important thing to be aware of is that if SID information is shared outside of the printshop - then the Status of the instruments that were used to determine SID values must be known. In addition, it is critical that all instruments within the printshop are set to the same Status. In North America, where many of the presses and their closed-loop color control systems are from Europe, it is not unusual to find the press set to Status E polarized while the handhelds are set to Status T unpolarized which can easily result in quite a bit of confusion in production.