Just a quick reminder, folks: as tempting as it is to just grab that little jewelry anvil you have when you need a bit of weight on a wet-formed piece while it dries, DO NOT drop it straight onto the wet leather.
That there was supposed to be the belt keeper on a mahogany belt, but I forgot to put a piece of scrap under the anvil first. Luckily it wasn’t something important-and I can always hang onto it for my next black belt project.
This is the result of a chemical reaction between wet leather and iron, and it can’t be cleaned off. All you can do is dye the whole thing black.
You can do the same thing on purpose if you like – it’s called vinegaroon, and is made by dumping a handful of steel wool and/or old nails into a jar of vinegar, which you then leave to simmer in the sun for a few days or a couple weeks, depending on how impatient you are. The resultant tincture will dye leather indelibly black, guaranteed. It is not to be trifled with, however: this is not for brush-dyeing the background areas, as the mixture WILL bleed past your intentions. This is for dyeing the whole piece. There’s a very informative thread over at Leatherworker.net on the subject.
The More You Know(tm)