Paint cracking when dry

[CM84]

Hi,

I am painting the final room of my recently bought 1930's semi. It is a small room on top of the garage, part of a 15 year old extension over the garage and out into the rear garden.

We applied some vinyl matt onto the old paint and after a second coat we noticed that we had honey-comb like cracks in most places, basically there are hundreds of tiny cracks in the paint.

As a test we coarsely sanded one section down and repainted, this made very little difference. I spoke to the decorator that painted my halls and larger rooms, he said that we could try sealing with some PVA as it may be the old paint reacting with the new so I tried that on a section, left it to dry for a few days and then painted but again this made very little difference.

I am thinking I may need to put some lining paper on instead but before I take that step, is there anything else I can do instead? Also, what do people think it may be that causes this, is it the paint reacting, the new paint, the plaster?

Thanks

 

[blightymam]

It could be that you're painting matt paint over silk, something more glossy anyway. If so, it can be a bit of a bugger but basically because a silk surface is shinier, the paint has trouble adhering. For that same reason, am glad that you used PVA in a section and not the whole place because paint doesn't stick to PVA so well.... bad advice really from your decorator.

You could try sanding with a finer grade paper to take off the sheen & washing the walls and try a section. If that doesn't work, perhaps use a primer, something like Zinsser 123. Or as you say, use lining paper

Good luck

 

[CM84]

Hi, thanks for the advice. I popped down to my local screw-fix and got some zinsser and applied it to a few sections, one sanded area, one not sanded and one that had PVA on it. The zinsser seems to have covered all the small cracks, i.e. They are not visible anymore. I will try putting my paint on top today and report back. Thanks

 

[blightymam]

Great news!
Happy painting

 

[CM84]

Hi, touch wood it seems to be drying ok, painted the few sections and it seemed to have a very shiny, smooth finish appearing. Proper test in the morning but hopefully the Zinsser has cracked it (pardon the pun) !! Thanks for the help, really appreciate it !