BEFORE
AFTERI am in the middle of redoing 2 cabinet doors that started to chip after about a year of use by a client. Here is what I recommend if you have any water damage to the existing finish BEFORE you paint.......sand it down to bare wood and them prime it with oil-base, stain-blocking Kilz primer.
When I painted this kitchen I lightly sanded all the cabinets front and back and used a bonding/self priming basecoat. The two doors that were under the kitchen sink had more water damage than I originally thought. After use, the paint started lifing a bit. So I took them to my shop and sanded off ALL of the paint down to bare wood and will be starting them from scratch.
You don't want to just lightly sand in a case like this because if your bottom layer isn't bonding, it won't matter how many coats you put over it, it will still fail.
I hope my failure will help you in the future. Remember, prep is the most important part of any painting project. Do not skip this step, or you will be creating more work for yourself!
Until then, Keep on painting.
