as the process unfolds, the direct-to-plate process begins with a weak bath and is gradually etched in baths which are increasingly acidic. Photo-polymergravure/polymer photogravure Photopolymer plates, usually used for relief and letterpress printing, can be used to make photogravure plates. These polymer plates, when developed, are a hard plastic, which allows for fewer impressions to be made. Some feel that they rival the quality of traditional copper plate photogravure, while others find that the lack of differential depth in the polymer coating compromises quality. The process involves a series of exposures of the polymer plate. First, it is exposed under strong light with a random dot screen placed on top of it (called an aquatint screen in fine art printing or a stochastic screen in commercial printing). Next, the plate is exposed to a positive transparency of an image. This transparency can be a continuous tone positive on film, but is most often made as a digital 'positive' (made in the same way as a digital negative) printed with an inkjet printer. The plate is then developed; for most types and brands of plates, this is done in water. After proper drying and curing, the plate can be inked and printed. The dual exposures produce an "etched" polymer plate with many thousands of indentations of varying depth which hold ink, which in turn are transferred as a continuous tone image to a sheet of paper. Depending on the quality, the resulting print may look similar to or the same as those produced with the traditional photogravure process, though without the same amount of three-dimensional depth on the surface of the plate, and arguably, the print itself. Two polymer plates commonly in use are Printight plates made by the Toyobo Corporation and Solarplates. See also Photoengraving References External links The Art of The Photogravure Printmaking Techniques, Defined and Explained in Plain English Photographic processes dating from the 19th century Printmaking Printing processes