R42-D 20cent Inland Exchange, No Price Listed

My question is: does normal silk paper typically contain wood fiber?

Thanks Bart.

"Has anyone seen revenue stamps with a high percentage of false silk/rag fibers"?

Depends on what you mean by "high percentage". I have seen some very "dirty" paper; filled with inclusions and fibers from the papermaking process. And I have seen literally hundreds of stamps at dealer's tables and in for certs as experimental silk that were not. Everything from pencil marks to wood chip inclusions to leftover bits of wrapper to fibers stuck down on the surface that a soaking would remove. This paper was only used for a short time during the time when Joseph Carpenter had the contract and most of it was used on the 3 or 4 most common catalog numbers. Plus the fibers don't always show, so there are probably some stamps that were on silk fairly frequently but most examples cannot be proven (the $2.50 inland comes to mind here, I have seen many examples that have all the characteristics of silk except there are no threads).

ALL the papers used for M&M's can have inclusions, which are usually either wood chips or stray fibers although the term is usually only used for wood chips. They show up even in the first half of 20th century postage at times.

Another perplexing fiber issue. Stamp on left is supposed to be an E-Silk, right, regular silk. Right stamp has fibers on face(2). The paper type of left stamp is the same as old paper variety. This is what I meant by many pieces of non-silk blue fibers. I hope this image is big enough to see clear. Black ovals are silk, red one not sure. Others are debris that didnt soak off. Paper on right feels thick like it should, but paper on left is thin and opaque. This has me confused, or the left stamp is not E-Silk.https://www.dropbox.com/s/q4h9jew7v...20b.jpg?dl=0

Hope the link works, and magnified image is clear enough. Thanks for everyone's help with silk paper 101.

I am suspicious of the left stamp being a genuine experimental silk, the paper seems too thin, a careful examination will show signs of the impression on the reverse. Also the wrong type of fibers. And the weave of the paper is too tight and too obvious. However it's difficult to be absolutely certain based solely on a scan at times. The right stamp is a silk paper, notice that even the smallest threads are still larger than any of the threads on the other stamp