T206 cleaning/soaking advice...

[icurnmedic]

I probably would not.
Likely already tried, and It is not going to change the "grade". May help the eye appeal , but could damage further. I like its current character

[JollyElm]

It's hard to tell until you have the card in hand, but the lighter word portions, like the 'BA' in "Base" and the 'S' in "Subjects," etc., may have thicker 'stains' obscuring them...or, like others have said, they may have been faded by previous efforts to clean. When you have determined which of those is the case, then you'll be able to move forward (or not move at all) more effectively.

[Pat R]

I don't think the ink faded I think it's heavier residue in some areas.

[steve B]

I bought a T206 with similar soot on the back.

Cleaning it went poorly.

I would give it the penny sleeve/ toploader and check it off my list.

[Bridwell]

I don't think this type of soot and other discoloration will soak off or clean off. I predict you will be disappointed if you try it.

[Leon]

I will echo the others on it. Those don't look like stains that are going to come off. Could be mildew...
.

[SyrNy1960]

Not sure if anyone has ever used this stuff, but it works great. It won't damage your card (well, I never had it happen. Always used a cheap stained card first to test it). I purchased many cards (50's, 60's and 70's) with stains, soaked them (individually) in a sealed-tight container for a bit, then once you open the container, you will see the liquid quickly evaporate on the card. Didn't always work (depending on what the stain is), but it most cases it did work.