I sanded, primed and painted some walls in my house a while back and now pine knots in the wood are showing through. What did I do wrong?
Most likely you didn’t use the right kind of primer. Pine knots are terribly stubborn and bleed through all kinds of paint, latex or oil. You must use a primer that is alcohol-based. You’ll find several on the market. For this particular project, you can re-prime over the entire area, or try just priming the pine knots and repainting. Be sure to sand those knots first!