Applied oxalic acid in a colored veg tan, then dyed, now it as like a lot of brown darker points all over the leather

[Abelc]

I have applied oxalic acid (1 teaspoon, in a pint of water) in a colored, tannery pre-dyed veg tan (is a 85 x 28 cm scrap they had in the store, they usually have some scraps, and i sometimes get them, usually natural, not colored one)

I let it dry like 1h 30 min,  then dyed (all the scrap, not cut yet) with fiebings light tan 50/50, a few coats, without letting the dye dry  between coats. Now it has like brown / darker dots in some areas of the leather. Looks like if were used some brown antique, in this case, i like it, but i would preffer to choose when i have that effect XD.

(While writting this i have gone to where i let the leather dry and now I just noticed that now it looks much better, i  dont find dark dots, it looks like lines like a spider web. or some bee panel form, but not dots as such)

I applied the dye, with a slightly unloaded rag -folded in half with some cotton balls inside- applying the dye in circles. I dipped the rag in the dye again, unloaded and so, applying coats, until I had the color I wanted.

As the color was getting darker, there were areas where there were dark spots (as if it was an antique), and some dark lines in an area that seems to have some damage. It was more noticiable when wet than after drying some minutes. Seems that some pores absorbed more dye?

Could it be that I have let the oxalic acid dry too little?

Could the fact that the leather was previously dyed (colored / pre-dyed veg tan) have affected the dyeing, or the use of the acid, over a colored veg tan, to clean?

I don't realize that I saw those dark spots before dyeing.

Those of you who use a sponge for dyeing, do you wrap it in a cloth? I have tried on a piece of leather, to dye it with a sponge, unloading it a little, and I did not like how it turned out.

I've been searching and haven't found much regarding this on the forum, that's why I ask.

How long should let the oxalic acid dry?

The dye has been drying for about 2 hours, I have buffed with a rag and no dye comes out.

I will do some tests in some 5 x 10 cm natural veg tan and see what happens, if i let it dry more XD

I tryed to make a photo, but the ceiling light makes quite difficult to see the darker spider lines/ web. And macro of the phone does not help XD
 

Edited March 19, 2022 by Abelc
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