I'm currently renovating my old building living room and I'm unsure which paint to use. The walls are over 50 years old and some still have lime plaster on them. A friend told me I should definitely go with lime paint, but at the hardware store I was also recommended dispersion paint. What's actually better for walls this old?
For old lime plaster walls, lime paint is actually the better choice because it's breathable and works well with the porous substrate - dispersion paint can cause flaking there if the wall is still actively "working." But you should check first whether the lime plaster is still in good condition or if dispersion paint was already applied to it before, because then you'll need to get the old stuff off first. What does the current condition of your walls look like - are paint layers already flaking off or are cracks visible?
The thing is a bit more complicated than you might think. Yeah, lime paint is often the better choice for lime plaster, but not automatically in every case. What really matters is what condition your walls are in. If the old lime plaster is still holding up well and isn't flaking off, then lime paint is perfect - it's breathable and works with the material instead of against it. But if your walls have been painted over multiple times or you've got moisture problems, it gets trickier.
Here's my insider tip: do a simple test beforehand. Grab a putty knife and gently scrape at an inconspicuous spot - if the old paint comes off in chunks and the substrate crumbles, you need a proper primer first before you even think about paint. That'll save you headaches down the road. With walls that old, it's often worth investing in a special deep primer for mineral substrates, regardless of which paint you go with.
Dispersion paint isn't automatically wrong, by the way - just only if the substrate is solid. It adheres better to already-painted surfaces and is easier to work with. Lime paint, on the other hand, you have to mix with water, it smells odd, and it's a bit finicky to apply. But in return, it really lets the wall breathe, which with old buildings is often more important than people realize.
I had the exact same problem during my last move and ended up going with lime paint - but the most important thing that nobody really explained properly beforehand: before you paint, you absolutely have to test whether the old plaster is still stable. If it's crumbling or feels like it's about to fall off, even the best paint won't help you. I ran a damp cloth over the wall and checked if anything came off - if that's the case for you, you have to stabilize it first before you paint. But after that, lime paint is really the right choice because it works better with old walls than dispersion paint does.
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