The Proofs
Made to check designs before final printing (on India), or as presentation sets (on card). Designs usually started with essays that became die proofs and then finally plate proofs (on wove paper or India). The proofs on India and wove are "true" proofs in that they were used to help develop and check (proof) the final design. The "card" proofs were actually for presentation sets and there were six printings of them. PR2-4 proofs on wove paper are hard to come by- but the paper is truly wove paper. However, many dealers and auctions get the PR2-4 on wove paper mixed up with the thinner PR2-4 card printing. Since the Scott catalog does not make it clear there were two card printings in the PR2-4 colors, once a dealer has a card set on the thick card (obviously card), they assume the set they have on (very) thin card must be wove paper. More information can be found in The Proofs.Warning! Plate proofs (on India) when perforated can pass as original PR9-32s! See Counterfeits.
Research on Newspaper Card Plate Proofs
There were 5 different printings or "emissions" of the proofs on card in 1879, 1882, 1890, 1893, and1894. The sets differ marginally by shades and card thicknesses. With great help from Greg Vaupotic, by studying over 1000 card proofs, and by buying several sets with their accompanying envelopes, I believe I have assembled the 5 complete sets and have them sorted out!
The 1879 and 1882 emissions could maybe be considered PR9-31 regular issue colors, while the 1882 emissions appear more like the 1879 colors of the regular issues, although the 9 cent value (PR 14) is retained from the first emission. It appears somewhere during the last four emissions, the 1885 "carmine" colors were used although each of the last four emission kept all the dollar values as well as the 9 cent value and an added 1 cent value (now you go figure out how "off" this makes the plate proof listings in the Scott Specialized catalog).
Each emission came in two unique envelopes. One envelope held the 1865 issue (PR2-4) and one envelope held the 1874 issue (PR59-80). I have 9 of the envelopes and would very much like to acquire the 1890 envelope that held the 1874 issue. I'm not sure if it's the same size as the one below, but it would have the same layout and lettering type, but with an 1874 date.
More information can be found in my publication
The Proofs.