We recently had the popcorn removed from our ceiling and replaced with knockdown. There was yellowing showing through the knockdown. The ceiling was then painted. After 2 coats the yellowing is still visible. Any suggestions
Usually when the yellowing occurs, I have found that there was a smoker in the house and/or gas heat is used.
If either of these is the case, you will have to apply 2 coats of a Kilz type stain stopping primer. 1 coat will not be sufficient. The application method should be to roll from one side to the other for the first stain killing coat and then cross that pattern for the second coat.