Painting - painting over oil base

I painted the trim in one of the rooms in my house. The trim appeared to have a latex paint. I painted over this with an oil base. The paint is now chipping badly and revealing stained wood with some type of polyurathane coating. Aparently the last home owners just painted over this with latex. What should I do? Also, what is the proper preparation for painting with latex over oil base?
Thanks for the help!

Welcome to the diy forums!

Whenever recoating interior oil base enamel or poly/varnish it is imperitive to sand and prime with a solvent based primer. I like to wipe the surface [to primed] down with a deglosser after sanding, this helps to soften the previous coat helping the primer to adhere better.

You've got a bad situation. Because the wood trim wasn't prepped right it makes it hard for any paint to adhere well. Ideally you would strip off all the paint and start over. With some luck you could sand well with coarse sandpaper [80 grit], prime and then sand with 120-180 grit and then enamel.

What kind of relults will I get if I do not completely strip the trim? As I understand you, I can sand, apply deglosser, and apply solvent based primer and this may work? If it does work, what kind life will it have before it starts to chip again? Stripping all of the trim would be quite a chore, or maybe you have some easy suggestions for this. I suppose I could also replace all of the trim, but this would be time consuming and expensive.

Thanks!

Deglosser is only benificial if used prior to priming unpainted poly. Too late to use it now - used over latex will result in a gooey mess. I was trying to say what should have been done - too late for deglosser now.

While stripping would result in the best job it is a LOT of work. If you rigorously sand what is on the trim now, hopefully it will remove any paint that isn't bonded well. You can then prime, sand and enamel.

The only thing I would add is that I wouldn't use just any solvent based primer, I would use a slow drying oil based primer(interior), i.e. benmoores 21700, in my experience the slow drying primers penetrate a bit better, allowing it to lock down the previous coats. But it definately sounds like you have a lot of work on your hands.