Occasionally a collector of these stamps may come across a color changeling -- a stamp in which the green has begun to change, and in some extreme cases change to a color that nearly matches the so-called "gray" color of the R184 to R189 series of stamps (the color of these stamps is a warm, sepia-like tone, not a cold gray in any way). An unused copy of R191 demonstrates this phenomenon (stamp #7 below):
The back of the stamp is marked in pencil by a previous collector as a copy of R185 with an R191 overprint. The collection that it came from (I believe a different collector than the one that wrote the pencil note on the back of the stamp) also had a note from the collector on the side as an R185 with an error. The color change on this stamp is extreme and seems rare according to my limited experience. But the ink changeling phenomenon on these stamps exists, is capable of fooling relatively advanced collectors, and doesn't seem to have a clear explanation by my limited research. More common are stamps that show lesser hints of color change, like those in examples 2-5 above.
I've never seen ink change like this on any other US issues, revenue or postage. What is certainly unique about these stamps among US issues is the varnish square. Richard Friedberg figures that the varnish is somehow responsible for the color changes, and it might have been, but the evidence doesn't lend itself neatly to thinking that varnish contact made the difference. Consider stamps 3 and 4 below, where the stamps remain somewhat green closer to the varnish. And, if the varnish was the cause of a change like that in stamp #7 below, why don't we see more of these changelings?
Lastly, the $5 stamp, R192, provides an interesting opportunity to test varnish as a cause, as some of the stamps were issued without the varnish square or the overprint.
The R192a on the right never had varnish applied. Yet its color is clearly yellowing like many of the examples of R190 and R191 above. In this case the explanation must involve the nature of the green ink itself. The knowledge is likely long-gone from the BEP regarding the ink on these stamps. But I suspect the right sort of chemist could help tell us what is happening.
I have a couple of non-changeling related questions, both involving how Scott lists these issues:
- Scott refers to these overprints as surcharges, though the overprint does not revalue the stamp. Why does Scott call these surcharges?
- In the "Warning" section below the image of R190 in the catalog, Scott tells us that the varnish was only applied to some stamps. This needs to be unpacked a bit doesn't it? First, most stamps appear to have the varnish, not "some". Second, if cut cancels are sublisted for the 1898 dollar values, why isn't the presence of a clear overprint on used copies of R190-R194 sublisted? And why isn't the presence of varnish sublisted? I recognize that dealers and collectors don't seem to discriminate here and that is almost certainly the reason that varnish presence isn't listed. But even without collector interest, the varnish clearly has an effect on these stamps, certainly with regard to how used, soaked stamps appear. Used copies that have been soaked but retain the overprint are much more collectable to me, a bit like the lack of a cut cancel on these stamps.