And here is how to remove a watercolor in 1928? Once someone on the back stamped. Watercolor damp (much earlier than the hit to me), print soaked, the ink leaked through the paper on the front side. Interestingly, themselves watercolors while not soaked.
Earlier, a watercolor on paper mat, the ink from the print got soaked and it, there's got a spot. So it is with which to experiment without risking ruin watercolor. Hydrogen peroxide (3%) has no effect on this spot.
I read that such stains are removed with oxalic acid. Got it (in solid form, chemically pure), but do not know what concentration to do as technically remove the stain. Tell me, please.
In principle, I have access to the university's chemical laboratory, so that problems with equipment or with any reagents not arise.
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