View Full Version : Will Oxalic Acid Affect Paint
11-28-2006, 10:12 AM
I am in the process of stripping the varnish on the sides of the cabin of my boat. She is a 1951 Concordia Yawl. There are areas where moisture has reached the wood and turned it grey. My plan is to sand then use Oxalic Acid on the grey spots still remaining. Will the acid affect my paint job on my decks and my hull as it runs off? Both paint jobs are new last season.
Any info would be most helpful!
11-28-2006, 01:00 PM
Oxolic acid will effect some paints. It is a good idea to keep a hose running and constantly wash off the runs.
11-28-2006, 02:27 PM
Jay is right. It depends on the strength of the acid solution. If you mix is fairly light (a fistful in a gallon of water), it shouldn't affect the paint, but do rinse it off the paint as you go to make sure. Oxalic acid WILL take the patina off of bronze. This isn't a problem, because discoloration soon blends back in as the bronze "re-patinas." However, I have found that the bronze patina carried off with the acid will stain topsides, so rinse well if it gets on the bronze.
Don't sand first. Instead, strip and then apply your oxalic acid solution. Keep applying until the grey is gone. Then sand. There is little point in sanding first because the water solution will raise the grain anyway and you will end up sanding after you bleach, one way or the other.
Be careful not to abrade the wood when bleaching. Strong bleach solutions will soften the soft wood between the grain and if you scrub with the grain, you will remove the soft wood, leaving a damaged surface that will take a lot of sanding to restore.
After bleaching and sanding, seal with CPES and then build up your varnish coats. The CPES will go a long way towards preventing moisture from leaching under the varnish and causing those discolored areas again.
11-28-2006, 06:24 PM
I will keep the water running and sand after I have bleached the wood.
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