Treating cracked ceilings when re-painting

[MisterBoy]

My old house has cracks in quite a few ceilings, typically 1mm or less - historic movement typically it's an old house. Japped hairline cracks but just too big for regular paint to reliably fill, and too small for regular filler.

I figured before repainting these rooms, I would like to have a go at the cracks with some product which is over-paintable. Google shows me a couple of options crack-filling paint and micro-filler, but I'd love some real-world experiences.

I'm aware it's not guaranteed but it seems worth a go for the small effort.

 

[opps]

Are they lath and plaster ceilings?

If you push the cracks can you see any movement?

I am a decorator. Providing that there isn't too much movement, I open the gap slightly. Then I vacuum the gap out and then brush in PVA. On occasion, it can lock the plaster together. I then push Toupret Flex and Fill into the gap and remove any excess. It is like a caulk with tiny fibres in it. It will shrink back. I then follow it up with a lightweight filler such as Toupret RedLite, or Red Devil OneTime. Both fillers are very soft so use 150-180g paper. On the upside, the dust will not become statically charged and cling to everything (unlike powder based fillers).

 

[MisterBoy]

Interesting, thanks. I don't know for sure about all but at least some of them are lathes, there are original ornate covings.

how wide do you want the gap to be ideally?

 

[Koolpc]

Another method, which I have seen done and works well is to open up the cracks, make holes along the cracks and squirt in low expanding foam. Wait for it to cure. Cut off excess, fill, sand etc. No more opening of said cracks.