I have a strange feeling you have not read this list's FAQ nor its
archives. Or perhaps it is already April 1st in Norway;-)
The original request referred to the carbon transfer process, which uses a
"tissue" better called "pigment paper" as it is not particularly thin, and
consisting of a coating made of about 10% gelatin and a dispersion of a
watercolor pigment, made sensitive to light with a dichromate.
The office supplier variety is not the same
Luis Nadeau