The literature on transfer printing repeatedly mentions a now-mythical material called pottery tissue or potter's tissue. This was a type of paper, the characteristics of which I have been unable to locate: fiber type, surface, weight, sizing or other special treatments if any were used.
I have tried numerous types of paper. So far, I have found only one that seems usable: sewing pattern paper. I know of no source for this as a raw material in small quantities (or any quantity). Fortunately, pre-printed patterns can be found for $3 in fabric stores and are thus cheaper than most anything sold at an art supply store. The print does not functionally interfere with this work, apart from visually cluttering the impression.
Classic technique used intaglio printing from a copper plate. Exact ink compositions seem to be poorly documented, and likely were considered proprietary when used by industry. One formulation is said to use pine tar as a base. A worker from a UK university suggested trying #8 burnt plate oil. That has proven to be a good suggestion. This stuff at room temperature is at least as viscous as molasses on a cold day. It must be heated, both when formulating ink, and when printing. I work in small glazed baking dishes ($1.49 each from Bed, Bath, and Beyond) on a hotplate.
For plates, I use Solarplate photopolymer plates. These are formulated on thin sheet steel, and can be cut with tin snips or heavy scissors. My typical plate is a couple of inches on each side, cut from 8x10" raw material. The original image is laser printed on overhead projection transparency film. A black line on the transparency will give a groove in the plate. The groove is filled with ink, the surface of the plate is wiped clean, and the impression is made. A black line on the transparency gives an ink line on the final impression. UV light hardens exposed areas of the photopolymer, leaving unexposed areas water soluble.
These plates may be exposed by sunlight or by other sources with sufficient UV light. I use a small UV fluorescent tube in a power supply enclosure that was built for, of all people, Avon (cosmetics) as some sort of skin condition disclosing light. This was almost certainly a vast failure, explaining the ready availability of these units, at least some years back, from surplus dealers.
Today we also have UV LED sources readily available. I have not yet tested one if these, except for post-development hardening exposure.
Using the small fluorescent tube, my typical exposure time is 19-22 seconds with the fixture held above the plate, transparency, and clamping glass, by a stack of two tuna cans on each side.
I work with a large sodium vapor safelight originally used for traditional darkroom printing. The exposed image can be seen faintly on the plate even before development.
Development is in a running stream or spray of tap water. I run the water a little warmer than cool to the touch. I also use a very soft plastic brush (sold for cleaning mushrooms) to gently scrub. I start with a stream of water, progress to the vegetable sprayer, then the mushroom brush, more spray, and more stream. I then dry with a hair dryer, then post-expose for 2x50 second cycles (the Avon lamp runs for around 50 seconds if you don't cut it earlier), then a but more time with a 3.6W UV LED flashlight (wearing Uvex UV blocking glasses).
For a press I use a modified hand-cranked pasta machine originally sold to work polymer clay. Modifications include removing the cross bars and scoops from the lower side of the rollers. I use a small square of real etching press cushion blanket (rubber with some fiber in it - got it from one of Daniel Smith or Graphic Chemical). I fold an 8x5.5" half sheet of used copy paper in half. Between the halves I place the plate, with dampened tissue on top then dampened newsprint on top of that. The cushion blanket goes on the outside of the face side. On the back side I place another folded half-sheet of copy paper, then crank this through the pasta machine.
This curls the plate: inferior to a real press, but I already had the pasta machine, and it cost less than 1/12 of what even a small press would cost.
The next challenge is to pull the tissue slowly and carefully from the plate. With luck, it peels without ripping, and you get a richly raised ink impression on the tissue.
Inking and impression are both done with the plate hot. This is essential to work with the thick and very tacky ink. Thick and tacky seems to be what is needed for transfer.
The tissue I dampen by spraying either with plain water, or with soapy water. Which works best is still unclear. The newsprint I spray with plain water.
Next: ink formulation.
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