Does Anyone Know What Kind Of Paper This Stamp Is Made From, Or Why This Is So Transparent ?

R18e is still a double impression and your stamp clearly isn't a double impression. R18a would be imperf and that isn't known on the 3 cent proprietary unless one has been certified recently. Yours is and shall remain an R18c.

Hello everyone Im back and have new info I researched on the internet .
First ,here is a copy of the Scott's catalog 2005.
Also I just read a story about someone in this stamp community that says he paid I think 200.00 for a r18e stamp and someone told him it wasn't one because it wasn't a double image .here's the page https://www.stampcommunity.org/topi...IC_ID=61910& if you would like to know.
also there's the website called revenue-collector ,https://revenue-collector.com/usrevs.shtml that explain the type of papers great to see .This might be the reason people are thinking there r18e isnt right or wrong or just dont know or not enough info something not right also I cant find any other pictures of this stamp I wonder why?
Well there is a r18e on this site http://www.usphila.com/us/stamp/pri...t-r18-page-1 and its said to be made from "other" paper not "old paper" "not painted on both sides" which Scott's catalog claim to be r18e.
An no mention of of the double image in the catalog.So which one is correct for future references. Its also funny that the main reason it's a r18e is because of the back of the stamp and no mention of the back of the stamp on the website revenue collector and no picture of the back of a stamp with old paper that I could see.

Dan,

There is no controversy here. Once again, from the 2017 Scott catalog, R18e is a double impression. Your stamp clearly isn't a double impression. The revenue-collector website illustrates double impressions. The link you provided to usphila.com also illustrates a double impression nicely.

In the same catalog, R18f is printed on both sides. In the case of a stamp printed on both sides, one key thing is that you can read the stamp from left to right on both sides. This is because it was actually printed on both sides. When the back of your stamp shows a backward image, like yours does, it wasn't printed on both sides. I showed you an image of a stamp printed on both sides.

The picture of the catalog you showed is an old catalog. Regardless of the lettering though, the values of the stamps are still similar. R18e and R18f are not cheap stamps. Unfortunately, yours is neither of those. It is still an R18c. Other than that, I don't know what to tell you.

Here is an image which illustrates the difference between a normal 'setoff' (stamps are stacked with ink still wet and mirror image gets on back of stamp) and a true printed on both sides error.
Don