Soaking and cleaning stamps

Thank you for the reply and i must confess that i forgot to do a search for earlier threads or posts.

I agree that 12% seems pretty strong to use as you even dilute 6% H2O2 for cleaning your stamps.

Hydrogen peroxide (in Italy we call it something like "oxigenated water") is a product that can have many uses at home, not just for washing stamps.
I've used it for mould-fighting, for bleaching wood, and for cleaning stamps.
But i've always used it in higher concentration than what you say.
In Italy the concentration is commonly indicated in volumes of oxygen released. Concentrated hydrogen peroxide is found at 130 volumes, which correspond to a concentration of 35%.
Now these products are no longer sold to private persons, but only to firms operating in the chemical sector. I was able to get a few liters by borrowing it from friends who used it for work, but now i've run out of supplies and it's several years i don't use it. But in other countries that's not the case. For example, in Spain i saw shops selling "household" chemicals, i.e. intended to be used at home, where you can easily find H2O2 together with a lot of other products...
Hydrogen peroxide is an unstable product, so it naturally tends to decompose releasing oxygen. So it is stabilized with the addition of sulfuric acid. So to be used, a few drops of an alkaline substance (i use ammonia) must first be added to neutralize the acid.
It must be handled with care, using at least nitrile gloves (resistant to chemical agents) and protecting your eyes, but once you learn it you handle it without problems.
To fight mold i use it concentrated. I apply it on the wall with a brush (obviously the brush must also be appropriate, otherwise all the bristles will get lost in a short time), leave it for an hour, and then nothing more, because by releasing oxygen it turns into water.
For stamps i use a lower concentration, 40 volume (12%). More simply i put one part of hydrogen peroxide and two parts of normal water. Then i put the stamp to clean and after i rinse it in normal water.
The results are usually good. I don't have stamps to show because i don't have the "before" as a term of comparison.
However, these are procedures that i don't use always, but only when the stamp requires it, which happened to me 5-6 times...
It has a lower whitening effect than sodium hypochlorite, but i find it less "dangerous" because, as i said, once the oxygen is released, it becomes water and does not leave the paper acid like hypochlorite does.

Easier to do than to explain. I suggest everyone to try it, but ok, safety first. Nitrile gloves and glasses.

About fifty at once. The water is usually getting muddy after fifty. And I have arthritis in my right hand and have to rest once in a while anyway, so I take a break then.

I personally don't pay much attention to fluorescence.

I save them for my wife in case she ever wants to make a collage. I'm like you, I don't like to throw them away if they look good and have flaws that would only bother stamp collectors. I used to save stamps with footprints on them or ones that had been folded up like a paper airplane because I'm an old softie, but I'm getting cold-hearted and ruthless as time goes on.

I think it's a law made by one of the ill-tempered Norse gods. I think those guys should be evicted from wherever they are and we can all move on  .

Those are nice stamps; I have some of them and I get Polish mixtures now and then to catch up with newer issues. Many of them have excellent designs. In recent years, they are getting kind of repetitive, though. What happened to XIV - XVIII?

I'd keep it here if it were up to me. But that's just me.

Hello eggdog
I made a mistake... XIX->XIV...