Color Variation 1932 6 Cent Washington

If anything at all,it has been an education in color criteria and the effects on value and collectibility! To me, just as in a socked on the nose bulls eye cancellation...it's over and above the value of the stamp itself.....just the fact that it got a two page response in the same day, to me , is a benchmark in my authoring skills!:))

Although the stamp may be "damaged", oxidation of orange stamps is something of a special case in my humble opinion because it is entirely reversible. If you dip the stamp for a couple minutes in 3% hydrogen peroxide, the oxidation is reversed, and as far as I know there are no negative side effects.

Not that you necessarily want to do it in this particular case, but if I have a stamp that I otherwise want in my collection, but it shows oxidation, I don't let that stop me as this is one "fault" that can actually be fully reversed.

Matt

Deleted duplicate post.

Matt

Since its a low-value item, it might be interesting to treat it with hydrogen peroxide. Just to see what is possible.

I'm not sure if this would be considered "shenanigans" or not, but I'd be curious to see what happens.

To the human eye, it appears the color is restored, but technically the chemical reaction is not reversed. This is why I don't use the term oxidation because it often gets misunderstood.

The chemical process that darkens the pigment is known as sulfurette (sulfur pollutant is being incorporated into the ink pigment), which causes the surface layer of exposed pigment to turn grayish (appears black to the human eye as the polluted layer grows deeper). Without getting into the actual chemical compounds (varies with pigments), the H2O2 does not remove the sulfur, but merely changes the sulfur incorporated pigment into yet another sulfur compound which is basically whitish (but appears translucent as a thin layer). By making that contaminated surface pigment transparent, you can now see the unpolluted pigment beneath. The contaminating sulfur is still there. You have chemically altered the surface pigment to make it "colorless" so that the underlying "correct" color can be seen.

Interesting khj, thanks for the explanation. I'm wondering, if the contaminated layer is still there, just transparent, will the process reverse itself (darkening again) or is the hydrogen peroxide treatment permanent? Assuming of course that the stamp is not exposed to further sulfur pollutants.

Very good point. The H2O2 treatment does not create a sealing layer. So technically, sulfur pollutants could still diffuse through the newly formed transparent layer -- but I would think it should take much longer. Since I don't know the thickness of these layers, I really have no idea how much longer, or if it thick enough to have any effect at all.

I gave a more specific example of the chemical conversion process in this thread https://goscf.com/t/15068.

Does anyone know if stamps in mounts rust (oxidize??) slower?

And of course, don't try that dipping with a gummed stamp. I would expect it to mess with the gum. Unless KHJ you know more about H2O2 than I do (which is likely as I'm a LOOOOONG time out of school).

It should stop sulfurette. Mounts do a pretty good job of protecting the stamp from pollutants in the air. However, you should always be careful not to get moisture trapped in the mount with the stamp. This happens most often when the mount has just been affixed. Over the years, I've seen lots of mint stamps in mounts, that turned out to be gum damage because of residual moisture in the mount or because moisture seeped in through the split-back/sides of the mount while affixing the mount.

Mounts will not necessarily stop foxing, but does help isolate the stamp.



That is correct. The H2O2 solutions are diluted with water. So directly immersing a gummed stamp will result in gum loss.

Thanks khj. I had forgotten they dilute the stuff you buy in the store.