Why is the paint on my interior doors peeling off in sheets?

You're definatly dealing with a classic case of **latex over oil** without the proper prep. In houses from the 60s, that trim was almost certainly finished with a high-gloss alkyd oil paint. If a flipper comes in and slaps modern water-based latex right over it without sanding or using a dedicated bonding primer like Zinsser BIN or Stix, the new layer just sits on the surface like a sheet of plastic. Since it can't bite into the old finish, it'll flake off if you even look at it wrong. You can verify this with a simple test using a cotton ball and some rubbing alcohol. Rub a spot on the original finish (where the top layer has flaked off). If the paint doesn't soften or come off on the cotton, it's oil-based. If you do the same to the peeling top coat and it dissolves, that's your confirmation. It’s a mess, but you don't necessarily have to strip every inch to the bare wood if you're strategic about it. For the doors that are allready failing, you need to scrape away anything that's loose. If it's peeling as badly as you say, alot of it might just pull off in large ribbons. Once the loose stuff is gone, you have to scuff-sand the remaining old oil finish with 120-150 grit sandpaper to give it some 'tooth.' If you don't want to deal with dust around the toddler, look into a **liquid deglosser** (sometimes called liquid sandpaper), though mechanical sanding is always more reliable.

After sanding and cleaning the surface, use a high-quality bonding primer. Don't buy the cheap big-box store brand; get somthing specifically rated for glossy surfaces. Once that primer cures, you can put a durable trim paint on top, and it won't budge. It’s a lot of labor for a house you just bought, but doing one room at a time makes it manageable and keeps those paint chips away from the kids.

The previous poster is spot on about the lack of bite. I’ve seen this exact mess in countless 60s ranches. If you want a finish that acutally stands up to a toddler and a vacuum, look at Benjamin Moore SCUFF-X or Emerald Urethane Trim Enamel. They’re night and day compared to cheap contractor-grade flat. Since you're worried about the peeling, skip the big box stuff and grab a Hyde 2-1/2" Contour Scraper to get the failing layers off cleanly. If you find the underlying oil is stubborn after you've scuffed it, I'd honestly just roll on a coat of INSL-X Stix before your topcoat. It’s the gold standard for bonding to those tricky high-gloss surfaces.

Oh my gosh, I just joined becasue I'm seeing the same thing in my new place! It’s so frustrating when you just want to settle in. Speaking of 1960s ranches, does anyone know if the actual door styles from back then—like those hollow core mahogany ones—are worth saving and refinishing properly, or shold I just upgrade to solid wood while I'm allready dealing with this paint disaster? I'm super pumped to fix mine up but I'm torn on the vintage look!

Spot on about the lack of bond. I’ve lived trough this exact nightmare. One detail people often miss in these 60s ranches is checking for lead before you start that scuff-sanding. Since you mentioned the toddler picking at chips, definitely grab a lead test kit. The old oil-based layers from that era frequently contain lead, and sanding it into fine dust is the last thing you want around a kid. Even if you're just using a liquid deglosser, it’s good peace of mind to know exactly what's underneath that failing latex before you start making a mess.