Uh Oh. 100+ year old home. I think the previous owners may have painted latex over oil. When I went to palm sand nicks and digs the paint gunked up on sandpaper. Hand sanding, same thing. Putty knife scraping just creates a larger spot with no end in sight. Tried Latex Bin primer over area to seal. Bubbles formed around the perimeter of the scraped area. What can I do to remedy this problem? I haven't tried Oil Based Primer over spots yet. Could that work? I'm not obsessive about how smooth the trim will look - I have 7 rooms; one room has 7 doorways/trim leading into and out and no money to tear out and replace trim and baseboards. Thank you in advance. Mrs. Painter(not)

Latex over oil just skins and doesn't penetrate. Are you applying latex again? Putting oil base over Latex will not work well. I believe you are sanding to heavily. What grit are you using? 320 is good.

Latex over oil just skins and doesn't penetrate. Are you applying latex again? Putting oil base over Latex will not work well. I believe you are sanding to heavily. What grit are you using? 320 is good.

I will get some 320 grit sandpaper tomorrow. So it's as I thought... Latex over oil is a boo boo. Latex is on there now... so latex will go on top. Do you think an Oil Primer would help seal the edges of the peeled paint? Will try to feather it down with the 320 grit. Thank you so much for your time!

I will get some 320 grit sandpaper tomorrow. So it's as I thought......Latex over oil is a boo boo. Latex is on there now......so latex will go on top. Do you think an Oil Primer would help seal the edges of the peeled paint? Will try to feather it down with the 320 grit. Thank you soo much for your time!

You can put latex over oil base but it requires a good "tooth" and a primer helps a lot. Oil over Latex is not a good idea as you are finding how hard it is to sand latex paint. A good oil based primer will seal as will a latex based primer. Amazing how hard it is to get primer off your hands! Just a light degloss with the paper is all you need. The paint will seal the edges, but you may need 2 coats in some areas as trim paint has small micron size particles and they don't hide as good as a flat wall paint. Be very careful with old trim and unknown paint. Although I consider the topic overblown, old paint may have lead in it. No paint in the last 40 years has lead in it. Good luck- don't use a cheap brush! Get a good trim brush, angle tip.