Found A New Rs138 Variety

I got a fun surprise for the New Year, my PF cert for a RS138 var went on-line. I was going though some dups and came across a RS138 that didn't seem to have a watermark. I thought it was old paper but it had a single blue silk thread visible on the back. Though not listed in the catalog, it looked like experimental silk paper to me, and some friends, so I dropped it off at PF last summer. It came back positive back in November but it took until now for the cert to be posted on PF's site: #562545.

So look through your RS138s and let me know if any more "e"s are out there. :)

The cert only has a photo of the front, so here is the back, which is the interesting side anyway. The lone thread is center top.

Scott lists RS138b as silk paper. So what's the difference between silk and experimental silk paper?

The most noticeable difference is that silk paper has silk threads throughout the paper, while experimental silk has a "few scattering" threads, as the Boston Revenue Book describes it. On a stamp the size of the RS138 there might be one thread.

Not a very technical description but this is is a quick overview with pictures:

http://www.rdhinstl.com/mm/papertypes.htm

Interesting! First of all, congratulations on your find!

The Toppan/Holland Historical Reference List of the Revenue Stamps US Including Private Die, (1899) does not list the C. E. Hull & Co. 1c Black Medicine Stamp as having been printed on experimental silk paper. However, the Reference does include thin, thick and experimental silk as "Old Paper". And it states that the stamp was printer on Thin "Old Paper".

The Reference does list the C. E. Hull & Co. 1c Black Medicine Stamp as being printed on 'silk' paper. It also mentions that silk fiber can be either red or blue and that fibers can vary in the paper from numerous to none or very little.

I wonder what reference material the PF uses to determine authenticity? Just curious as I am not in any way, shape or form disputing the cert. I'm just reading the Reference.

Moyock
experimental silk fibers are short, often 1/8 inch or less and seldom more than one-three per stamp. the paper is thicker and softer than that of the full silk, but not as soft as some of the watermarked types. the ends often have a clipped appearance. full silk is longer and much more abundantly scattered throughout the mix, and is much more obvious both on the face and the back of the stamp. both types have to appear to be mixed in with the body of the paper and not on the surface only. look at a few Scott listed full silk items under a glass and the difference will become apparent.

It should be remembered that experimental silk paper is not simply old paper with a few fibers in it. It is a different paper entirely, whiter, somewhat softer and more fibrous then old paper. If one looks at the perfs on this stamp there are fibers on almost every perf tip, and occasionally in the perf holes themselves as well. Old paper rarely shows fibers at the tips, almost never in the holes, and never remotely as frequently as here.
It should be pointed out that in theory, a sheet of regular silk paper stamps MIGHT have a stamp with few or only one fiber in it. In fact, this occurred in the large partial imperf sheet of the RO140b (cert 482271). There were a couple of stamps in that multiple with only two or three fibers each; however in the case of a single stamp there is no reason to assume that is the case.

red fibers are in my are experience seldom found on m and m issues. the reddish appearance of fibers in the pink paper issues are in my opinion caused by the jute fibers of the bag absorbing the dye used to color the paper during its manufacture. The RO140b sheet had such an irregular distribution of fibers that some items (from the missing portion of the sheet) could have had none. the items with only one or two fibers within the part sheet were not in my opinion short enough to be considered experimental. The Boston Book mentions the paper types and silk colors as a general reference for all revenue stamps, and does not mean to infer that all papers were used for all issues. In theory any stamp in current production, or obsolete issue could have been put to press to test the various forms of paper for suitability and could exist on that paper.

i offer an additional clarification: as I recall the specifically mentioned red, and red and blue fiber paper in the Boston Book was used for Special Tax Stamps.
the specific paragraph mentioning the various m and m papers is meant to alert one to the fact that major variations of thickness exist, and should not be read into that all issues are found on all types. there were major paper and gum supply problems over the life of these issues.