Inks

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Ink and Color-

Ink, and more specifically color, is a subject where complexity can ramp up exponentially. For our purposes to date, I have been focusing on mixing ink for a pleasing color and applying that color directly to the paper through a screen.  A color that is pre-mixed and applied directly is known as "spot" color.  This is unlike "process" color where dots of four base colors are placed in close proximity to fool the eye into seeing new color.  Magazine print is entirely process color.  Examining a magazine print under magnification will reveal that it is typically comprised of only four colors.  Cyan, Magenta, Yellow and Black, or "Key".  Screen printing is entirely compatible with CMYK printing processes but to take advantage of CMYK printing, the original work should be prepared via computer as hand cutting the correct sizes and sheer numbers of ink dots would be nearly impossible.  I'll touch on CMYK screen printing later, for now it's all about mixing the colors we want to use directly.

What kind of ink-

Plastisol or Water based inks?  There is a lot of information online concerning ink types.  For paper media, the water-based inks work well and it's nice to be able to let the prints air dry. There also isn't a need to heat set or washing machine test paper prints durability.  T-shirt printing, however, has an entirely different set of demands. Plastisol inks play a useful role in t-shirt printing. Plastisol inks, however, do not dry on their own. They need heat to cure and become permanent.  A flash dryer for setting ink between colors and a belt dryer for the final cure are needed for to use Plastisol inks effectively. Choose inks by the job they need to perform and the equipment available for drying and things will work out satisfactorily.






Mixing-

Mixing inks to a pleasing color is easy to do but how this is done needs attention to avoid waste.  Mixing darker colors into lighter colors will save ink.  For example, mixing a nickle size amount of black ink into a cup of white ink will produce a nice grey.  To get that same grey color, starting with a cup of black ink, might end up needing a gallon of white!

Take notes while you're mixing. This does not need to be precise but should be good enough to get you close to reproducing your color at a later date.  If a really nice color is mixed up it's nice to have a rough map about how it was made.  Put a smear of the mixed color right on your notes for future reference.

Once that "just right" color is found sooner or later there won't be enough.  No worries though, simply mix in some ink extender.  Extender can be mixed in to the ink to get more volume for printing.  It will not significantly change the color but will change the consistency.  If you're a little bit short, extender can save the day.  It does have limits though, too much extender can drop the viscosity of the ink so it will flow through the screen on it's own rather than being forced through with the squeegee.  If the ink gets a mind of it's own it will make a mess -nothing lasts forever!





Ink Properties-


Not all inks are completely opaque! This can be an advantage.  Insightful  planning and use of transparent inks (made transparent by mixing extender) can give a three color result from only two colors where the  transparent inks overlay.






Before a print run it is a good idea to rest your ink choices on a scrap paper of the kind you'll be using for the final print.  Avoiding surprises also avoids waste and results in better results.  Testing inks can be done on a scrap of paper simply by pushing ink through an old screen with a squeegee exactly as if a print were being made.  In this case however an stencil or exposed image isn't needed since we're only testing for how the chosen ink will behave and look on media.  If that Packer green and yellow looks great in the buckets but looks like bad veggie soup on the paper maybe a bit of color tuning is in order!

Ink to be used for CMYK printing needs to be mixed precisely so the four colors interact with each other properly,  the recipe is shown below.




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