Have you heard of OSB? It is short for oriented strand board, a type of building material made of strands of smaller logs. It is a different sort of wood from both plywood and chipboard in that it is made by combining the three layers wood strands and resin, put together at 90 degree alternates. It can serve many purposes in a building project, such as being laid down as subflooring or flooring. If you do intend to use it where it can be seen, you can get quality OSB that has been factory sanded for a smooth surface that can be stained for a more beautiful finish.
Step 1 - Prepare
OSB is more susceptible to moisture than other building materials, so once it has been cut, the ends will have to be retreated to keep the seal and prevent damage. Make sure your OSB has been moisture treated, and then you can choose your stain. Most stains or varnishes that you can use on plywood, you can use on OSB, but gas-permeable variety is recommended. It will bring out the various strips of wood that have been used and will get into the pieces to make them stand out.
As stated above, if you want a smooth finish, you need to buy the factory sanded product. If this is not what you have, then run the wire brush over the panels to remove all loose particles of wood and resin. Then, rub it down to make sure nothing snags later.
Make sure you have your gloves on and a tarp down under the pieces you are staining before you begin.
Step 2 - Apply the Stain
Now that you have yourself, your area, and your wood ready, open the varnish or stain and mix it well. You can use a stir stick or a mixer on your drill. Then, dip a brush into the liquid to get a small amount on it, and spread it on the wood, going consistently in one direction. Let it dry an hour or so after the first coat to make sure whether you want it darker. Also, be sure to apply it as evenly as possible so it doesn't soak in differently, leaving darker spots than others. Thin coats and smooth applications make for the best final result.
Step 3 - Add a Finish
Now that you have it stained your OSB to the color you want, decide where you want it to have a subtle gloss or a high shine. You will need to use a top coat in order to protect the wood and the stain, but the level of gloss is up to you.
Once you've chosen your finish, dip a clean brush into it to spread over the board. Again, brush it on in a couple thin layers, moving in the same direction as before. Try not to leave brush marks and use a high-quality brush so you can avoid leaving bristles behind.
Let the piece dry at least overnight before moving or handling it. If it is humid in your work area, allow about two days or put fans nearby to circulate air around the piece.
Step 4 - Clean Up
While your OSB dries, you can take time to clean your brushes. To remove stain, varnish, and polyurethane, you will need to soak the brushes in mineral spirits or paint thinner. Do not touch the chemical with your bare hands; always wear protective gloves, and dispose of the thinner properly when you're through.