Printing Color on Color?

To obtain a third color when printing color on color, you need to use transparent inks. You also need to use minimal ink coverage — reduce your ink on the press. However, a lot depends on what you have seen and how it was printed. Many times the effect of color on color is achieved printing halftones or screened images so that the overlapping color shows through in the gaps between dots and the eye mixes the two to get a third color. There’s a lot to know about printing color!

Bob

Ahhh. Ok. Never knew about transparent inks. Would these be different from your standard Rubber Opaque? Where does one procure said inks?

Maybe someone can tell me—do ALL colors come in transparent, or just white (and then you mix)? I haven’t been able to find anything but WHITE that says transparent.

Thanks!
Chris

Ink pigments have varying degrees of transparency, depending on the pigment. Some of the most transparent inks are process yellow, process magenta (a bluish shade of red), and process cyan (a greenish shade of blue). There is also process black, but that is not really transparent; it is just made to use with the other three process colors. These inks are made to print over each other and make different colors. You can also mix them to make other colors which you can print with, like green, purple, etc.

I don’t know what inks you have but some of them might be fairly transparent. You won’t know until you draw them down. To draw them down you will need a drawdown pad (or sheets), and a drawdown knife.

A drawdown pad is a pad of white uncoated bond (like copier paper), which is around 4 X 6 inches (the exact size isn’t critical). Each sheet must have a horizontal black stripe across the middle of it, about 1 inch wide. (I suppose you might be able to run sheets through a computer printer to get the black stripe, but a printed black stripe would be better).

For a drawdown knife, buy a putty knife (not too flexible), about 3 inches wide from a hardware store. Buy some fine sandpaper (about 200 grit), and, on a flat surface, rub the edge of the knife on the sandpaper, at various angles, until the knife edge is not sharp but is very smooth and straight. Mostly, draw the blade edge across the sandpaper back and forth, like you were cutting something. You want the knife edge to be smooth and rounded, not sharp. Then, carefully (so as not to cut yourself if the blade is sharp), draw the tip of your fingernail down the knife edge. It should feel very smooth, and should not be sharp enough to cut you (be careful!!!!). If you feel any roughness through your fingernail, keep polishing it with the sandpaper.

For the actual drawdown procedure, put the drawdown sheet on top of maybe 20 sheets of paper, and if you clip that on a clipboard it works well. Put a small blob of ink on the top of the paper, spread it out sideways a little, then put the knife edge across the paper and “draw it down,” as we say.

Then look at the ink. You draw the ink across the black stripe because if the ink is opaque, it will hide the black stripe better. If it transparent, the black stripe will show right through the ink film. So, you can tell how opaque the ink is.

Look at this video…..then you will get a better idea.

https://www.youtube.com/watch?v=8uvmSVEh76A

Thanks so much, Geoffrey! Do you know where I can buy these “process” colors? Any link to a website, by chance? I’ve ordered transparent white, but don’t see the other colors listed as “process” etc.

Thanks!
Chris

Here are a few suggestions.

http://www.vansonink.com/categories/Sheetfed-Inks/Four-Color-Process-Ink...

http://gansink.com/process_inks.asp

You mentioned rubber base ink so I assume you have chosen that type of ink to get. However, the inks listed above are oil base. I didn’t see all the process colors listed as such, for rubber base ink, but Van Son does list Pantone yellow, Pantone Rubine, and Pantone Process Blue, and I think you would be pretty safe with those. Rubine, for instance, is the pigment in Process Red.

Here is Van Son’s rubber base ink:

http://www.vansonink.com/products/Rubber-Base-Plus.html

Other suppliers who specialize in selling to letterpress people like us:

http://order.nagraph.com/ink.html

https://www.boxcarpress.com/choosing-letterpress-ink/