I wanted to make a stacked text sign with the top layer and bottom layer text painted different colors. I sprayed a board and let it sit overnight and then put the masking on (shelf liner from Lowe’s, not oramask). I did a small test and discovered that the paint peeled up when I pulled up the masking.
I did another board and let the paint cure for a week but the same thing happened.
I had put shellac under the paint. Should I have tried some on top as well? I know that I have masked over paint before without trouble but it has been a while and I can’t remember if I did something different.
Sounds like your paint did not have a good bond to start with. You did it overnight and did it again after a week indicating the particular paint you used had a weak bond. It does take a week or more for most paint to dry and harden thoroughly. Most of the instructions of paint say you can handle it in about an hour but most have a warning not to put it under stress for some time.
Shellac is compatible with most oil or water based paints. There are two types of shellac ready to use. The Traditional Shellac Zinsser makes has some wax in it. They have another shellac called Universal sanding Sealer by Zinsser. Be sure to use the Universal for an under coat. The Universal is dewaxed.
If you use flaked shellac and disolve it in aclohol you mix it and after a while wax rises to the surface and you have to skim that off. The ready to use Zinsser Traditional Shellac finish has some wax in it.
Putting shellac over the paint would not hurt anything but the paint has to have a good bond to start with.