Get a couple of evaluations and estimates from people who specialize in architectural refinishing ... the walnut paneling in our 90-some-year-old house. In spots, the wood has been lightened ...

I think the paneling is original to our 1966 house ... Although it’s possible to buy oxalic acid labeled for use in refinishing wood (a 12-ounce tub of Savogran Wood Bleach is $16.99 on Amazon ...