Question about painting concrete basement walls

I spent 4 hours last weekend prepping and painting a section of my basement wall with drylok, and this morning I found a spot the size of a dinner plate peeling off where the old paint didn't fully bond, has anyone else dealt with that kind of adhesion failure on old masonry?

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xena_rivera631mo ago

Holy cow, four hours of work and it's already peeling off in a dinner plate sized chunk? That's brutal, honestly. I've messed with old masonry before and it's such a gamble, even when you think you've scrubbed everything clean. Sometimes that old paint just has a mind of its own and refuses to let go of the wall, you know?

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elizabethp931mo ago

Jumping right into it... I think there's a common mix-up with Drylok, it's technically a waterproofing paint not a bonding primer, so if the old paint underneath was something like a latex or oil-based coating that was already peeling anywhere, the Drylok will just sit on top of it and eventually flake off with it... I had a spot in my own basement where I tried to paint over some old calcimine paint and it did the same thing, big chunk right off the next day... you really gotta scrape off anything loose first, maybe even use a wire brush or a grinder with a masonry wheel to get down to bare concrete in the problem areas before you put on the waterproofing stuff.

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