Jan Harrell has taught workshops using Imagon Ultra as a replacement
for PnP. Imagon Ultra is a photopolymer film like the Puretech
material. Imagon Ultra works very well for etching for enamelists.
Gives good detail and you don’t have to remember to reverse text.
According to the polymetaal site
"Puretch is perfectly suited for “etched intaglio-type” techniques.
In these techniques it is superior to ImagOn (Ultra) (Riston) because
the film is much thinner. It is therefore a perfect resist. The
ImagOn Ultra films are too thick for this purpose. If used in the
original thickness, it leads to loss of detail (dispersed light).
Therefore Keith Howard recommmands to thin the film in a soda bath.
By using Puretch however you do not need to thin the film, and even
the quality of the print is better compared to a thinned ImagOn
(Ultra) print. Puretch is available end of May 2002. "
Depending upon what you wanted either would work. You can get
Imagon Ultra from Daniel Smith. The polymetaal site has good
instructions for print people.