Vinegaroon, the USDA Way

[Gosut]

Came across this in Department Circular 230, Home Tanning, 1922, published by the US Department of Agriculture, on page 17, under "Dyeing Black." It first lists dyeing with a commercial dye, but then lists dyeing with iron liquor, (vinegaroon). The amounts are for whole hides, but the basics are:

Mix iron filing or turnings with vinegar and let stand a few days, making sure there is always enough iron that some is undissolved.

Make a tannic acid solution and soak the leather in it for about two days. Remove and rinse off particles from the solution, then mop or brush on the vinegaroon. Rinse off excess vinegaroon and put leather back in the tannic acid solution overnight. Repeat until black in dark enough.

What caught my attention is the method ends with the tannic acid bath. That would add more tannic acid to any iron acetate remaining in the leather, but I'm wondering if it's also diluting or neutralizing any free vinegar in the leather.

I found the department circular by going to archive.org, selecting texts, and doing a search on USDA home tanning.

[chuck123wapati]

33 minutes ago, Gosut said:

Came across this in Department Circular 230, Home Tanning, 1922, published by the US Department of Agriculture, on page 17, under "Dyeing Black." It first lists dyeing with a commercial dye, but then lists dyeing with iron liquor, (vinegaroon). The amounts are for whole hides, but the basics are:

Mix iron filing or turnings with vinegar and let stand a few days, making sure there is always enough iron that some is undissolved.

Make a tannic acid solution and soak the leather in it for about two days. Remove and rinse off particles from the solution, then mop or brush on the vinegaroon. Rinse off excess vinegaroon and put leather back in the tannic acid solution overnight. Repeat until black in dark enough.

What caught my attention is the method ends with the tannic acid bath. That would add more tannic acid to any iron acetate remaining in the leather, but I'm wondering if it's also diluting or neutralizing any free vinegar in the leather.

I found the department circular by going to archive.org, selecting texts, and doing a search on USDA home tanning.

ok  i see, they are dying the leather as they tan it, previously tanned leather doesn't need a tannic acid bath.