Every so often the last decade or so, we get a little stark reminder of how computers are changing the world, making some businesses obsolete. Around 1990, every typesetting house I'd ever used in Los Angeles went out of business. What had once cost $100 could now be done for free by any kid with Microsoft Word and a good set of fonts. Other markers of this kind come along from time to time. The latest for me is the announcement that the Graphix company is discontinuing its Unishade and Duoshade illustration board. I think they were the last company in the world that made this kind of art paper.
Explaining what it is will be easier if I just focus on the Duoshade variety. Duoshade board is art paper that has two patterns printed on it in different invisible inks. When you buy the paper, you also get little vials of developer fluids that make the invisible ink visible. You do your drawing in black ink and then when it comes time to add "tones" to it, you employ the developer fluids. One developer fluid brings out pattern #1, which in the example here is a pattern of lines that create a (roughly) 25% grey area on the page wherever the fluid is applied. The other developer brings out a 50% pattern. You can see this better in the enlargement below…
This, by the way, is an illustration that Jack Davis did for one of the MAD paperback books.
As you can see, what results is a drawing with two halftone patterns on it. A printer can shoot the page as line art because the "grey tones" are already screened. The paper has been used often for black-and-white illustration work, or sometimes artists employ the Unishade kind which only has one pattern. It came in very handy for years…but now that so much art is being done on computer, the halftone tools in Photoshop have rendered it obsolete. Just another thing that's gone away on us…