Post-Stripping Treatment with Oxalic Acid
Wood that is turned gray by stripping agents can be restored to natural color by a combination of sanding and oxalic acid. June 18, 2010
Question
I have a client that I am building some cabinets for and they have a 200 year old home. The client has been stripping the old woodwork and also had the interior doors stripped at a local "dip n strip". The chemical strippers have left the wood a dull grey to brownish grey color. Is there anything that can be done to bring back some of the wood’s original color tone. The wood is all native pine. They would like to finish it with a light stain and then urethane. Thank you for any advice.
Forum Responses
(Finishing Forum)
From contributor C:
Try oxalic acid. Follow the directions on the label. Wear gloves and a dust mask. You should be able to return the natural color of the wood.
From contributor P:
Oxalic acid is the normal post-stripping treatment. You can get it at paint stores or from your coatings distributor. Add the fine crystals to warm and stir in until it won't dissolve any more (saturated solution). Brush onto the wood and let dry (overnight). Wash off the residue with rags and water and let it dry again. Sand lightly with fine paper to smooth the raised grain and proceed with finishing. Don't breathe the crystals when mixing or cleaning the bleached wood - it's a fairly strong irritant. Pine gets blotchy with some stains. Thick gel stains work well. Test in an inconspicuous area or on a piece that would be easy to sand out if you needed to.
From contributor J:
I'd do any heavy sanding (cutting off the fur for example) before the oxalic. I've found that heavy sanding can burn through to the unbleached wood, leaving dark patches again.
From the original questioner:
Thank you everyone. I will pass this on to my clients. The woodwork has a lot of nice character I as well as they would love to see it come back to its old patina
From contributor L:
You might have to apply the oxalic acid solution several times or more. On really dark wood or water damage, it takes several applications. If you don't get the look you want, apply it again until it stops lightening the wood.
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