questions: painting latex over oil
We are preparing to paint trim/doors in our house. We think it is oil based, and it does not have much of a gloss. A contractor friend recommended lightly sanding, followed by liquid sandpaper, followed by two coats of semi-gloss latex. In order to hopefully avoid a big, peeling mess, we are doing lots of research, which raises lots of questions. Any insight from the expert painters here would be greatly appreciated!
1. We THINK the trim is oil paint. A painter that we hired for other paint work said it was oil paint. Some of the interior closets are yellowed, suggesting it is oil. I wiped some trim with liquid sandpaper, and it did not seem to affect the paint, or make it tacky, as some people suggest it would. However, when I tested the paint with rubbing alcohol and with goof off, a little bit of paint came off, not a lot, but I've read that oil paint should not budge. Can we be pretty sure it's oil based?
2. We tried some of the liquid sandpaper, after lightly sanding, and it did not seem to affect the paint much. We are using Klean Strip easy liquid sander deglosser, which does not specify if it's for oil or latex. It's described as "to help new paint and varnish bond adhere to old finishes. It deglosses paint, enamels, varnish & more." Will this product work on oil paint?
3. I've been reading some suggestions to paint within a 30 minute window of applying deglosser. The Klean Strip product says it can be painted over within 10 minutes but does not say anything about having to paint within a certain time period. Do we have to paint within this time window?
4. Some people say primer is required, some say sanding is sufficient. The current finish on our trim is very smooth. Do we need to prime? If so, do we need to use an oil based primer?
5. To repair small dents and dings in the trim, do we apply spackle, sand and apply primer? Do we have to use an oil based primer?
Thanks so much for your responses!