A badly weathered piece of wood siding on your house is not only unsightly to look at, it may be lowering the value of your home. This can easily be fixed by sanding down and then repainting the wood. Primer is typically used as a first layer on wood, before the paint is applied, because it soaks into the wood pores and helps the paint adhere better. Although it requires a lot of elbow grease, the best way to remove primer from wood is by sanding.
Wash off the wood with a liquid cleaner to remove as much dirt as possible. Place a few drops of dish soap into a bucket and fill with warm water. Soap off the wood containing the primer. Dry with a towel.
Scrape up as much of the primer with a paint scraper as you can. Move the scraper along the grain of the wood as you work.
Attach a piece of coarse-grit (between 40 and 60) sandpaper to a sanding block. Fold the paper in place over the face of the block and clamp into place with the handle. You can also use a power sander, if you have one available, to make the job faster.
Sand in the direction of the grain in the wood. Start at one end of the wood and work your way down, always sanding in the direction of the grain. Continue sanding in one spot on the wood until the primer has been sanded away before moving on.
Remove primer from wood floors by renting or purchasing a floor sander. These have large, circular discs on the bottom that make removing primer from wooden floors much easier.
Clean up any debris with a shop vacuum.
If you don't have a power sander, rent one for an afternoon or a few days from your local hardware store.
Wear goggles when sanding. If you are sensitive to dust, you might want to wear a respirator as well.