Best Way to Remove Defthane?
Issue: Issue 331
Posted Date: 7/30/2013
I've enjoyed your magazine for the past few years and all of the information it gives me. Now I'm in need of help, and thought you may guide me where to look. I have a dining room table that is in need of the top being refinished. It currently has a layer of Defthane on it, and I'd like to find the best finish remover for the job. It's 36-in. square and made of English oak. - Clinton Scudder
Tim Inman: "Best" is a tough test. For my money, I'd use a paint remover that is high in methylene chloride content. This will be a non-flammable remover, and it will be a very effective one. It will, in all likelihood, also be the fastest acting remover. You can purchase these strippers in a thickened "paste" formulation which makes it easier to use on a small job like yours. As with all chemicals, be sure to work in a well ventilated area, and wear protective clothing. If you get a strong methylene chloride stripper on delicate skin, it can feel like a bee sting.
How do you know if the product you're evaluating is high in methylene chloride? Lift the can. MC is very heavy, about 12 pounds per gallon. Water is about 8 pounds per gallon. Alcohols are lighter -- maybe as low as 6 pounds. MC is also expensive, so many formulations contain, yes, water -- plus alcohols and other flammable components to dilute the MC, and that makes them both cheaper and flammable.
A side note: methylene chloride is a "dry" chemical. It won't affect hide glue joints. It will attack synthetic glues like contact cement, though. If your table top veneer might have been laid with a contact type adhesive, take note. The cheaper flammable type strippers with alcohols will attack hide glue joints.
And finally, read the label instructions and follow them. Resist the temptation to "help" the stripper by constantly brushing it back and forth to stir up the remover and paint. MC is very volatile. Each time you disturb it with your brush or scraper, you are helping it to evaporate -- and not stick around on the paint to do its work. Counterintuitive, but true. For your table top, I'd suggest putting on a thick coating of remover, then laying a sheet of disposable construction plastic over it to help keep the remover from drying out. Then go have a cup of coffee -- maybe two. Come back and test. If all is good, remove the remover and finish. Clean up with mineral spirits, and let it dry. If the remover darkens the wood (Chemical lesson alert -- but for another time), you may want to apply a dilute oxalic acid wash after the wood has dried to bring it back to original color. Then, you're good to go on building your new finish.
Chris Marshall: As Tim suggests, patience is key to stripping a finish. If you can curb your enthusiasm to get the new finish on, and spend the time it takes to get the old finish completely off, you'll end up with a better looking table all around. Personally, I don't enjoy stripping finish, but oftentimes the end result is worth the fuss that goes into it.