Q&A OF THE WEEK: “How Do I Strip The Clear, Factory Coating So Brass Can Be Polished?”

Q: Black stains are forming on the brass entry hardware of our front door, and I want to get rid of the discolouration. I’ve tried polishing but nothing happens. I’ve heard that brass sometimes has a clear coating applied at the factory to stop the metal from tarnishing, but it also seems to prevent polishing. How do I strip the clear, factory coating so the brass can be polished?

A: I just finished dealing with a brass ceiling light fixture that had the same black staining problem. In my case a water leak in an upper floor ran down into the light fixture in the ceiling below. When everything dried out there was deep black staining on half of the fixture. And you’re right, polishing this kind of problem away is considerably more difficult because of a clear coating applied at the factory. The coating is nothing but lacquer, but until you get it off, no significant polishing of the metal can occur. With the lacquer gone, the brass becomes truly exposed and polishable.

The easiest way to remove the lacquer is with lacquer thinner or acetone. It will take several wipings to get it all off, but removal is a necessary first step. You know you’ve gotten it all off when you apply polish and rub and black stuff comes off on your cloth right away. That’s the tarnish. If you’re not getting black stuff, you haven’t removed all the lacquer.

When it comes to actual polishing, I’ve had excellent results on brass using an old-time product called Brasso. I first used it as a boy to make pennies shine. Daub it on liberally with a clean rag, rub it in, and then let it dry for a few minutes before polishing it off. You may have to repeat the process a few times to get all the way down through to bright metal, especially if some residual lacquer remains. A toothbrush is ideal for applying polish to nooks and crannies.

At this stage you have a choice. You can leave the brass bare and polish it from time to time to keep it shiny. That’s a good choice for entry hardware because it’s so easily accessible for polishing. Alternatively, you can spray the brass with more lacquer from an aerosol can. A light coat is all that’s required to keep the air from contacting the metal, triggering tarnishing. That’s what I did with the light fixture I mentioned earlier. Light fixtures are high up and hard to polish.

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– Steve Maxwell