A primer 3 is essentially a protective layer that you apply before the first coat of paint. If you are painting over an already-painted surface, you may be able to avoid a primer 3 altogether by using a 2-in-1 paint and primer 1 3 product. However, if you are painting a surface that has never been painted before or changing the paint or finish type, it would be a good idea to prepare the surface using a traditional primer 3. Primers 3 should also be used when painting over hard, smooth surfaces like glass or tile. All three types of primers 3, oil-based, latex-based and shellac-based can be used under latex paint.
I hired a painting company to paint my house and garage. Price was about $5,000.Sherwin Williams paint T-1000. When he was questioned about the paint peeling two days after he painted the garage he quit even with a contract not a very professional person. So,now I have to find someone else to paint my house.After 3 weeks of them trying to paint around the rain. The original time frame was 3-4 days.Yes 3 weeks and all that got done was a small two car garage that could have been done in two days.I know he did not prep correctly and properly I will end up having to redo the garage. I went to Sherwin Williams and got the colors.So beware even with a contract and good references. House Painter Broomfield Colorado