Looking For Insight On 3 Cent Washington

Has the color been changed due to chemical reactions or could this be a true color? It's unused and the color is very even throughout.

That happens when the lead that is contained in the ink reacts with sulphur (which may come from the coal mine next to your home or from "old style PVC sheets"). Sometimes called "Lead poisoning".

This process can be stopped by using a hydrogen peroxide solution for used stamps (and changing the cause of it so that it doesn't restart). It will revert back the color to whatever it was originally. It does not remove the lead or the sulphur from the stamp, though.

For mint stamps like yours, it is much more diffcult as the H2O2 solution will obviously remove the gum. So another method has to be used, like a very thin paintbrush dipped in the H2O2 solution and striking across the front and immediately dry the stamp so the solvent doesn't penetrate the stamp and attack the gum. Likely takes a lot of practise on cheap stamps...

Appreciate the insight. I like the looks of it so it may just stay as it is. Thank you.

In the future, you should handle your stamps with tongs, not with your fingers. You can easily transfer fluids onto the gum and impression side accidentally. Glad to have you as part of this forum.

Greetings HWDear
The correct way, in my experience to use H202, is not to submerse any stamp in the material. Instead put several drops of the peroxide in a plastic dish, such as a cleaned mustard or mayonnaise top. Put a plastic screen on top, and your stamp goes face down on the screen for a few hours or a day. As required. I personally use a plastic piece of gutter guard as the plastic screen. Recently I bought a bunch of WFs 6 cent orange, all mnh. All heavily toned from atmospheric reaction. It took two days to clean them up. Always after subjecting any stamp to any material let it air out, (in the case of Ronsonol I can smell it on a stamp 2 hours later) untill you have confidence the material is evaporated.

cheers mark

An additional thought. Back years ago high sulfur coal was widely used in the USA. As a consulting agronomist we very seldom were concerned with low sulfur in the ground for crop. We were receiving anywhere from 2 to 5 lbs./acre free from the (acid) rain. With the mandate of low/no sulfur coal use that stopped, and everyone ran the sulfur numbers in the soil. I can't help but think that atmospheric sulfur could have a deleterious effect on stamps. Not uncommon now to add S2 or Diammonium sulfate for fertilizer for crop

Lead chromate (chrome yellow) reacts with hydrogen sulfide to produce lead sulfide, thus the pigment darkens. Hydrogen peroxide converts lead sulfide to lead sulfate, which is white (see The Whitening Effects of Peroxide Gels on Darkened Lead White Paint
(McFarlane, available online).

There may be a way to convert the lead sulfate back to lead chromate. Conservationists working on van Gogh's sunflower paintings would know. Otherwise the original colour is not going to be precisely recoverable. I'm assuming that the lead in a 3 cent stamp is chromate, and not red lead.

Possible lead pigments used:

Lead oxychloride (Cassel Yellow)
Lead chromate (Chrome Yellow, American Yellow, Baltimore Yellow)
Lead antimonate (Naples Yellow)
Plumbic Tetroxide (Red Lead)
Basic lead chromate (Chrome Red, American Vermillion)
Lead chromate and basic lead chromate (Chrome Orange)

Lead chromate is PbCrO4 and basic lead chromate is PbO-PbCrO4.

Source is "Colour Index", published 1924 by the Society of Dyers and Colourists.

This off gassing drywall was also used in individual home remodel and repairs. Had a frined affected by the off gassing after it was installed. The affected stamps had not problems the 20-30 years prior to renovation stored in the same room.

According to Wikipedia it's the incorporation of ash from burnt coal into the gypsum that causes the problem with Chinese drywall. The ash provides food for Acidithiobacillus ferrooxidans , which farts out hydrogen sulfide and sulphuric acid.

So this whole stamp-browning thing is caused by farting bacteria.