Last year at a ceramic educators conference, a guy did an interesting demo. He used a d!git*l cam to make it quick and easy, but basically he printed on a coated paper used to make decals. The printer was some ancient beast that he guards zealously; it uses a toner that contains some form of iron (probably as an oxide). Apparently most of today's printers do not use the magic ingredient.
Once printed, the decal is dunked in water and slid onto a ceramic object. For his purposes he used a plate that had already been fired with a white ceramic glaze. With the decal in place, the piece would be fired again. The transparent decal film burns away, and in this case, the iron component appeared as a sepia-like tone. Probably a more common technique is to create silk screens and make your own screen ink using the powdered minerals, eye-of-newt and bat wings commonly used to create glazes. Even what are considered relatively low firing temperatures will burn off most organic stuff.
There is probably a way to use a half-toned screened image and a rubber blanket to offset print a photographic image onto ceramic also.
DaveT (who plays with ceramics a bit, but hasn't tried photos)
IIRC, the 'dusting on' process can be used to apply pigment to a gelatin-based image transer. Subsequent firing burns off the gelatin and fuses the pigment permanently.
A quick ceramics primer:
The temperatures called for can range from 700 to 1200 degrees for low-fire techniques like the iron transfer decals to 2500 degree (farenheit) or so for high fire porcelain with cobalt decorations. That famous blue seen in both Chinese and Delft pottery is cobalt. Most photo processes are done in what is known as overglazing, a method of adding colorful topcoats to an already fired piece that is then fired again at a much reduced temperature to fuse it to the glaze. Gold chloride is used like this to produce the gold rims on fine china services. The overglazes are much like enamels baked on to the surface of the glaze. Underglazing, a much more permanent process, has the decoration applied to the once-fired but unglazed bisque-ware, which is then covered by a clear or translucent glaze and fired to a higher temperature. Underglazes tend to be monochromatic or muted colors and are dishwasher-safe. Many colors burn off at high temperature. Reducing the oxygen available during the firing process will result in changes to many glazes and can result in colors that cannot be produced any other way; certain reds are reduction colors because most red pigments burn off at relatively low temps.
The article speaks of porcelain enamel, a fired-on paint similar to what is on your stove or refrigerator. The temperatures for that are much lower and the firing time much shorter than actual clay work. Images can and have been placed on fired surfaces in many ways– and the possibilities are exciting. I only meant to speak of the traditional use of printed images; iron, manganese or cobalt for the most part, and the temperature ranges used in pottery manufacture. Since we probably won't be eating off any of our images (melamine plates with pictures are made all the time, but I haven't seen any clay ones) I think there may be some way to print on a tile... I just don't know it.
Originally Posted by Fast Frankie
Hmmm, I wonder whether you could use a process like carbon printing and use the appropriate metals instead of carbon in the gelatin mixture. The final transfer would be onto the unglazed ceramic. I suppose some sort of clear glaze would need to go on top (?). Essentially, you'd be making the decal with gelatin, dichromate and the appropriate metal powder. Then on the other hand, it might just all run off too.
Warning: this comment is from an engineer with almost no experience in ceramics and only a bit more with carbon printing!!