Swiss Trial Prints by Derrick M. SlateI stumbled across this the other day while searching for any
information about WIFAG.
Here is part of the Introduction:
Swiss Trial Prints are a fascinating aspect of Swiss Philately. They are beautifully produced, using many colours,displaying motifs, scenery, mountain passes, postal coaches, airplanes and many more subjects. These Trial Prints have been produced by several printers: P.T.T. (Swiss Post Printing Works), Courvoisier and WIFAG. They are sometimes incorrectly named essays, proofs or specimens (some prints have this word appearing on them), whereas they are actually trial impressions produced from specially designed cylinders made for the same printing presses that were used for issued stamps. It is a large PDF file of 135 pages and is slow to load but
do yourself a favour and go through this even if you're not
a fan of the aspects a stamp printing.
Most informative, well written and presented, sharp, clear colour
images throughout.
Fantastic stuff.
http://www.swiss-stamps.us/Research...alPrints.pdf