Thread: painting over timber finishes

I hope you can help me. I have quite a lot of internal timberwork, which appears to be stained and covered with a clear matt finish. I now wish to lighten these rooms and paint over this timber. What undercoats or preparation should I do?. Today i tried A zinsser product Bullseye 123 and after painting it on a test area it didnt appear to adhere very well. After visiting their website I did find it takes some 14 days to cure. Is it ok to topcoat before that? How can i be sure that it all wont just peel off. Any help appreciated.