Repainting my shed (wood siding/trim), the prior owners left behind old paint. The paint they left was oil base, so I went out and bought oil base paint. But I'm concerned that they possibly repainted using latex paint. I read that you can determine the paint type by rubbing the old paint with a Q-tip dipped in alcohol, if paint come off it means you have latex. I did that and the paint came off.
So here are my questions:
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Is there a better way to determine if my shed has oil base or latex?
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If my shed has latex can I use a water base primer over the latex and then top coat it with the oil base paint I bought?
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Am I better off just buying new latex paint?
Best Answer
Alkyd over latex is touch-and-go - well, it works or it doesn't. That depends on several things.
First, is the latex paint new? If it's less than a year old, forget it - it will not be happy being overcoated with an alkyd (oil based) paint.
Second, you can do an adhesion test. If it passes the adhesion test, you are all set - you can use that paint. Google's not much help here because everybody wants to sell you elaborate paint-test equipment. You only need a razor blade, packing tape, and a cotton ball. And this procedure explains it. The test is fairly over-wrought, but you can shortcut down to what matters to you. I've bolded the parts that I'd do.