Rich black - the problem of black in presswork

Like all process color inks, the black ink that is used in 4/C printing is transparent. As such it cannot cover ink, or black out the paper, as thoroughly as one might hope. Instead, black ink by itself actually appears to the eye as ranging from an apparent black when it's used to cover very small areas to just a dark grey when it covers large areas.Even though it appears greyer, the box on the right is the same printed 100% black as the text on the right.
The solution to the problem of grey blacks is to boost blackness by printing other inks under the black ink. This effectively darkens the brightness of the paper over which the black ink will be applied thus making the black "blacker."

Blacker black strategies

There are several ways to making a black blacker:

1) Apply a screen tint of a process color - magenta or cyan down before the black.

2) Apply a mix of process colors - cyan, magenta, and yellow down before the black.

3) Apply two hits of black ink.

The first option is sometimes called a "rich" black, while the second is called a "super" black, and the third a "double black."

With a Rich black the other process ink is usually a 60% tone of cyan. This causes the black to appear “blacker” because the second ink color increases its density. It also makes the black "bluer" which adds to the darker appearance. A 60% magenta could be used instead of cyan to impart a warmer appearing black.Left: 100K/60M. Center: 100K. Right: 100K/60C.
Rich blacks are typically used whenever the image is larger than 1 square inch and smaller than about 9 square inches in area.

A Super black, where 3 process colors underlie the black, is typically used when the black area is larger than about 9 square inches in area. The typical screen percentages are: 50% cyan, 40% magenta, 40% yellow, and 100% black.Left: 100K. Right: 100K/50C/40M/40Y.
In contrast to using a single process color, this screen tint combination preserves the neutral appearance of the black. This screen ink combination also means that the maximum amount of ink in the black amounts to just 230% coverage which should not cause any on-press issues like excessive drying times.

Unfortunately a Super black can be problematic on press because it is used for large black areas while at the same time using the same inks that are used for the color-critical image areas. That can cause a conflict on press if ink densities need to be adjusted to align the image colors with the proof while keeping the Super black neutral and at the correct density. To solve that problem, printers may opt to use two hits of black ink. The first black ink is tied to the CMY of the images, while the second black is independent of the image. That allows the press operator to adjust the CMYK inks as necessary to get good color on the images with the second black ink only being applied where a large area of black is needed. The downside to this strategy is that it turns a 4/C job into a 5/C job (CMYKK) which may increase production costs.

The black booby trap

On a computer monitor, there is only one way to represent black - the screen is black when there is no light coming from the display. So a 100% black, a Rich black, a Super black, and two hits of black will all appear the same on screen.A 100% black bar, a Rich black bar, a Super black or, two hits of black ink all appear the same on screen.
100% black bar as it appears in print if it is set to "knock out" of the background image.
100% black bar as it appears in print if it is set to overprint the background image.
A Rich black bar - 100%K/60C as it appears in print. The 60% C not only serves to darken the black but it also knocks out the background image which eliminates any "ghost" images caused when black simply overprints a background image.
Because the on-screen appearance of the black may appear the same despite being made up of different screen tint combinations it is critical that the Rich, or Super black be clearly identified as such in the custom color menus of page layout and illustration applications. Create the color and name it according to its function and make up. E.g. Black for standard process black, "RichBlack 100K60C" and "SuperBlack 100K50C40M40Y"

From pressed steel toys to presswork

Recently I purchased a 1940s toy dump truck at auction.

Doing a little research on the background of the toy I discovered that "Lincoln Specialties", or as it was more commonly known, "Lincoln Toys" has an interesting connection with printing. The company that made it - "Kay Manufacturing" - was founded by father and son team, Haven and Fredrick Kimmerly in Windsor Ontario. With the Second World War raging in Europe, business was good and they received government contracts to build ammunition boxes and truck fenders for the Canadian Army. Their products also included bicycle carriers and kickstands as well as automobile visors and the ultra-collectible steel "Coca-Cola" licensed coolers.

But as the wartime economy slowed down new products were needed to replace the loss of government contracts. They decided to focus the company's efforts on the burgeoning post-war baby-boom toy market. So, the Kimmerlys set up "Lincoln Specialties" in 1946 in order to market their new "Windsor Steel"-made products and by 1953 the toy selection had grown to over 24 different styles of trucks in three different sizes and two different cab designs.

Unfortunately, despite their succeses, increased foreign competition and unsuccessful bids to win back automotive contracts that were abandoned during the toy boom forced Lincoln Specialties out of business in 1959.

Fredrick Kimmerly (1920 - 1985), who was always artistically inclined, had admired how printers had lithographed the decals on his trucks and the products they carried.So, in 1968 he launched Standard Printing as a family owned business specializing in thermography, and embossing. The business continues to this day under the stewardship of Fredrick's eldest son Paul, his wife Lori and their two children.Sadly, Paul does not own a Lincoln toy himself - but he does own the original English pressed steel toy that served as the prototype for the now, highly, collectible Lincoln toy trucks.

Speckles in presswork - secret of the yellow dots

Most manufacturers of laser toner printers have embedded within them a technology that leaves microscopic yellow dots on each printed page. The dots are intended to identify the date and time of the printed sheet (if known by the printer itself) as well as the printer's serial number in order to identify the owner and location of the printer.
On the left, a close up of the "secret" yellow laser dots. On the right the same dots viewed under a blue light to enhance contrast and visibility.
The dots, which are normally invisible to the naked eye, form a code which is used by authorities such as the U.S. Secret Service to investigate the printing of counterfeit money made with laser printers.
The secret yellow dots are typically too small to be seen at normal viewing distances.
The yellow dots are a bit larger than the halftone dots used to create the actual image.
Unfortunately, if the laser printer is not calibrated properly, or depending on the design of the graphic being printed, the yellow dots may be dark enough to be visible. Also, the dots may affect the reporting integrity of color measurement instruments – e.g. a cyan patch intended to be 100% cyan only may contain yellow security dots and cause a slight green shift.

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.

Specks in presswork - ink in the non-image area

Press operators are often seen bent over a press sheet examining it under a loupe. One of the things they should be looking for, but often miss, are specks of ink appearing in the non-image area of the presswork.A 20x enlargement of solid ink patches showing small speckles in what should be unprinted paper. The pale thin lines are paper fibers.
(Click on image to enlarge)
A 200x enlargement of the above image showing the small speckles of ink more clearly. The pale thin lines are paper fibers.
(Click on image to enlarge)
There are several possible causes of this problem.

Tinting (also called toning). This is caused by contamination of the fountain solution by either ink, or some coloring matter from the ink. Since fountain solution is all over the non image area, any coloration will be likewise. It is usually caused by the fountain solution breaking down the ink but it can also be caused by the plate. Usually though, tinting will appear more like a very pale wash of color over the non-image area rather than discrete specks of ink on an otherwise clear background.

Redeposit. This occurs when specks of developed/removed coating are re-deposited onto the plates later in the processing cycle. It's typically due to dirty rollers or contaminated rinse water, but can be exacerbated by hard water in the rinse or improper exit roller pressures (allowing more developer to carry-over into the rinse). These specks of coating adhere to the plate and accept ink and print on press.

Incomplete processing Problems with the mechanics of the plate processor like bad brushes and/or pressure may not scrub the plate well enough to remove the particles of coating from the unexposed areas of the plate. Typically though, there would be a more general toning in those cases (but not always).

In general, if the specks appear only in one color then that press unit is more likely the cause of the specks and it's also more likely that the problem is tinting/toning. However, if the specks appear in all four colors then it is more likely that the plates are the cause of the problem and it's important that the press operator inform prepress about the issue.

From the print buyer's point of view, there will likely always a few specks appearing in the non-image areas of presswork. If this is a critical concern, as in security printing, then it is best to discuss the issue with the print supplier and perhaps agree to what would be an acceptable number of specks per square inch/centimeter.