This is my first Instructable so please bear with me if it is rough. I was looking through the site for homemade wood stains a while back, and I came across this one: https://www.instructables.com/id/Introduction-to-wood-staining/ The author has a brief note how to make a stain out of old nails in vinegar and that is just what I was looking for. I believe in reusing or repurposing things that would otherwise be thrown in the trash so using old nails to make a stain for recyled pallet wood projects is perfect. This is a wood stain that I have used since finding the instructable by chiok, and get dramatic results from. It is very simple to make and I love seeing the finish that this stain gives recycled pallet wood. The pic above shows the most recent knife handle and sheath that made from a pallet brace, and then finished with this rusty nail wood stain. The ingredients you need are:

Rusty metal. Any old nails, screws or metal scraps will do as long as they oxidize red; this means iron or tin.
Vinegar. I used the cheapest white vinegar I can find. You may get different results using different vinegar types.
A jar or bottle. I used a cleaned out spaghetti sauce jar. You can use any bottle or jar you have available, even the vinegar bottle itself.
Masking tape
Marker
A magnet (optional)

Step 1: Put the Rusty Metal in the Vinegar

Drop your rusty metal into the jar and then pour in the vinegar. Fill to about 2" from the top to allow for the expansion of the acid-rust chemical reaction. Put a cap or lid on the jar to prevent vinegar evaporation, but do not tighten the lid all the way. Back it off a quarter turn. You need to allow for the expanding gasses to release. Trust me, either you provide a way for the expansion or the expansion will provide its own way. My first batch I ruined the lid because the gasses pushed up and up until it slipped the threads. Let the stain set overnight and swirl it around the next day. I do this for 5-7 days until I see the vinegar turn from clear to a cloudy, light brown. In a pinch I have used the stain the next day and put on multiple coats, but I get best results by letting it sit for a few days. You will probably see a dark brown scum layer form on the top. Don't worry about it, just swirl it in to add to the color.

After you get the desired color, remove the metal from the container. I use two methods for this.

Pour the stain into another container, then shake out the bright and shiny nails. Don't worry, they'll rust up again in a day so you can use them for your next batch.
Use a magnet along the outside to drag the metal up and out of the jar.

Don't worry about the sediment that is floating around. I just wipe it off when I finish the wood work. Often I will leave one small nail in the stain to continue its reaction and further darken the stain. That is how I get a deep black color on oak and a dark brown on cypress.

Step 2: Try Your Stain on Different Types of Wood

This rusty vinegar wood stain has different results on different woods. It is not a consistent color on all woods. Also, the amount of time you allow the rusty nails to sit in the vinegar has an effect. The longer they stay, the darker the stain. Don't leave the corroded metal in there for more than two weeks or you will fill the entire empty space with a scummy growth. If that does happen, don't worry. Just swirl it back down into the liquid. Commonly, I have to let the stain sit on the wood overnight to get the full effect. Here are two sample photos that I took on the different types of wood I have in my shop. the first one is a first coat on the first day, the second one is with two coats after a night of drying. I wrote in pencil on the different woods but they may be hard to see, so from top to bottom here they are:

pressure treated lumber
white oak pallet (or maybe hickory, that is some very hard wood)
raw bamboo
closet pole (unknown wood)
white pine on left, then pallet top plank (unknown wood)on right
yellow pine pallet wood on left, then maple on right
shipping crate (unknown wood)on left, then red oak on right
cypress on right below red oak.

As you can tell from this list, I reuse a lot of pallet wood. I bought one oak 2"x4" to use for my whittling projects, and then decided I needed to find another source of hardwood. Look to your local pallet recycler for their cast-offs is my advice. Also, look for anyone making a log cabin in your area and offer them a piece of your finished work in exchange for a truckload of their castoffs. I know that is not part of this instructable, but I got a lot of pine and cypress log segments from cabin builders in exchange for some whittled cuttlery.

Step 3: Amaze Your Friends With This Awesome Stain.

Now put a tape label on your jar or bottle and use a marker to indicate what the contents are. I just write "Rust in Vinegar". Use this stain on your own wood projects. Apply to wood with a brush along the direction of the grain.

My most common project is that I whittle knife handles and sheathes. This wood stain dramatically changes the natural color of the wood. I use salvaged pallet wood all the time and find that the rusty vinegar reacts well with it. In these photos I show how a light colored hardwood turns black with just one coat. Between the first picture and the second there is only a minute transpired, but you can see how the sheath is already turning black. I let it dry overnight, and then burnished it with a dremel to make it nice and shiny..

Thank you for checking out my first Instructable. I hope you use this to make our own wood stain and crank out some fantastic projects.