This is a great trick if you want a beautiful matte black "dye" for your leather. When I say dye, I mean that more like it chemically turns your leather black, differently than any dye that I have worked with. Not only does it look **** sharp, It's incredibly cheap when you consider that you can get a gallon for about $4. ($2 for a gallon of vinegar and $2 of wire wool from dollar general.)
What you will need:
Jug O' Vinegar, I like to use about a gallon, but its really up to you and how much you want.
Steel Wool. Use 0000 fine grit.
Gasoline.
Container with seal-able lid. This is going to be what you keep it in.
Start with your wire wool. Douse it with the gasoline and light it up. Wire wool is treated with oil and that will impead the process, so your burning it off at this point. Let it burn out. Next, let it sit in water for about a week so it rusts. When that is done, its ready to go. Next, pour your vinegar into the seal-able container, fill it as much as you need, then put your burnt wire wool in and sit that **** on a shelf for a about two weeks. CAUTION, gases build up during the process and it kind of burps and there is a good chance that some will leak out and stain whatever you have it on, so don't put it above anything important. Don't keep it in sealed glass either, contents under pressure and all that.
Two weeks have passed and now what you have is vinegaroon, also known as vinegar-oxide. Your steel wool rusted=Oxide. It looks like muddy water. Use a cheap foam brush and paint it on. Bend your leather a bit so it "drinks" up the vinegar as you paint it on for a uniform coat. Also, two weeks is kind of on the short end. Depending on how your conditions are where you keep your V-roon, it may take longer. Best conditions seem to be hot and lots of sunlight. Its also kinda like a pet plant in that you need to feed it every few months, only if plants ate rust.
When I am done and satisfied with the paint job, while its still wet, I rinse off the leather and wash it with some lava soap to take out some of the vinegar-ific smell, which can be pretty strong for a while if you don't.
If you use electricians tape, you can actually tape in designs that you can paint over, it will leave a sharp edge to it.
All in all, despite what seems like a big paragraph of care tips, v-roon looks great and is a very cheap alternative if you plan on using a lot of black dye. Also, its historically accurate. People have been using it practically since that very first sicko peeled a cow and started making crap with its skin. Hope you have success if you try this, its very easy.