By Gene and
Step 1 : Protect the surrounding surfaces
Clean the area around the butcher block so it's free of dirt and grease and let it dry. Then mark off the work area with two layers of masking tape. The idea is to protect any surrounding countertop, cabinets, backsplash, or appliances from being hit by the finish sander.
Step 2 : Hand scrape the surface
Begin scraping off the existing finish with a paint scraper. Make sure the blade of the scraper is sharp. Then carefully pull the scraper in the direction of the wood grain, across the wood surface to remove the top layer of finish, scratches or burn marks.
Step 3 : Remove stains
To bleach out stains and blotches, use a solution of one-to-one household chlorine bleach and water. Use a small scrub brush to work the stain out; you may need to do this more than once to attack a really dark stain.
If stubborn stains remain, get wood bleach (sold at hardware and paint stores and home centers) and follow the directions on the box.
Rinse the area thoroughly with water and then neutralize it with a rinse solution made of one-to-one vinegar and water.
Step 4 : Sand the surface
Wear a mask and safety goggles to protect yourself from the grit you'll create sanding. Use a finish sander and different grades of sandpaper until the scratches and cuts or gouges disappear. Begin sanding with a course 80-grit sandpaper, followed by a 120-grit sandpaper. Then use a 240-grit sandpaper to final sand the surface so it's blemish free and smooth to the touch.
Step 5 : Apply mineral oil
Use a clean rag to wipe on a finish of mineral oil (found at drug stores) for the final step allowing it to soak in. Let the oil soak in and apply a second coat.