I'd heard that you can make your own stain using just steel wool and regular vinegar. I was intrigued and had to give it a try myself.
ball of fine steel wool
sponge brush or rag
Put a ball of fine steel wool in a glass jar and fill with white vinegar to about 1-2 inches from the top. Replace the lid and let sit for a few days until the steel wool has dissolved or nearly dissolved, giving the jar a shake once or twice a day.
Yep, that's it.* It's just that easy.
*I'd recommend leaving the jar on a paper towel and carefully opening and closing the jar before shaking it. We noticed that our jar built up quite a bit of pressure from the chemical reaction of the steel wool dissolving in vinegar and the pressure needed to be released a few times a day.
Once the steel wool has dissolved, put on some rubber gloves, give the jar one last shake and start staining!
The stain is very deceiving at first.. when you initially put it on it just looks like you're putting dirty water on the wood - it doesn't look significantly changed. However, as it's exposed to the air and dries it rusts and gives the wood a beautifully rustic, warm color. Once it's completely dry, take a rag to rub the loose rust off - you're done!
If you're using this process for a sign or something that won't be touched when finished I'd leave the wood raw like this. If you're thinking of using it for a table or something you will come in contact with, I'd strongly suggest sealing the wood to keep you from getting rust stains.
I didn't have a project in mind for this process, but I love how rich the color turned out! I think I'll be staining the edges of this board and turning it into something.