Scott #492 - Weird Gum On Back..

Hi guys..Take a look at this Scott#492...I had to do a bit of imagery to bring out the lines on the back so you can see them..Never seen this before..I went 10 stamps either side and they did not have the same gum design...Could be normal if some one else can look at their stamp..Thanks.

Wert, my collecting specialty is the US Transportation Coils. They were issued between 1981 and 1995. Because they were in use and printed such a long time there was obviously quite a bit of variety in paper.
Some of the paper used showed ridges in the gum somewhat like that. Paper with that particular gum texture is called paper type II and IIa, and was supplied to the printer ( the Bureau of Engraving and Printing ) by the Eastern Fine Paper Corporation of Brewer, Maine. Paper was delivered to the BEP already gummed, and different mills supplied different paper and gums!

Peter