Hairline cracks in new plaster

aylesby

Last summer we had walls skimmed and painted after removing wallpaper. A number of the walls now have two meter long hairline cracks. Some are vertical and others diagonal. At least one diagonal follows an imbedded central heating pipe.
The walls were painted with emulsion after a two week drying period. It’s a detached house built 1967 without nearby trees. There is no history of subsidence.
How do I decorate to hide these cracks? My first attempt to paint over a crack filled with decorators chalk proved most unsatisfactory and has only highlighted the crack.

Atelier

The lines are most likely where the plasterboards join. If you have embedded your central heating pipes in the wall then your walls will be more succeptable to cracks.

Those that I have had have been painted over and quite often that will cure the problem without the need for filling. It you cannot live with the hairline cracks and they keep coming back then you might need to put lining paper on the wall and repaint but that would be a shame having just replastered.

aylesby wrote: »

Last summer we had walls skimmed and painted after removing wallpaper. A number of the walls now have two meter long hairline cracks. Some are vertical and others diagonal. At least one diagonal follows an imbedded central heating pipe.
The walls were painted with emulsion after a two week drying period. It’s a detached house built 1967 without nearby trees. There is no history of subsidence.
How do I decorate to hide these cracks? My first attempt to paint over a crack filled with decorators chalk proved most unsatisfactory and has only highlighted the crack.

macman

Just use decorator's filler (the flexible sort), fill it slightly proud with a flexible blade, rub down when dry and repaint.
It's not subsidence, that is when you get cracks in the underlying masonry. If you are talking about internal partition walls then it's just the plasterboard joints, as Atelier advised.

misgrace

Atelier wrote: »

The lines are most likely where the plasterboards join..

Unfortunately, this is not always the case, it happens a lot on just ordinary skimmed walls.

I havent a clue what causes it, I come across this many times in my jobs, I have painted new plaster thats been dry 8 weeks, and still its cracked, some say its the plaster drying out too quick, or plastering with the heating off, then whacking it up, no one ever seems to know the answer., it just happens.

The one by the heating pipe, could have cracked because of the hot pipe, but as for the others, it could be anything.

If the cracks havent opened up , and are just a line, you can sand these cracks and the crack will go flat, and disappear.
If the crack has opened up,then you need to make the crack wider by opening the crack with a knife, then you can fill, make good, then repaint.

Money_Grabber13579

If they are hairline cracks, they aren't anything to worry about. Nothing to do with subsidence either. It's more than likely just the plaster drying out, and will just need a re-paint. 2 weeks doesn't seem like that long a time for plaster to dry though, so it's quite possible it was painted too soon, especially if it was a total re-plaster and not just part of a wall.

aylesby

Thank you for all the comments.
Does anyone have recommendations for the flexible filler?

misgrace

I take it that 'using flexible filler' you mean the decorators caulk that comes in a tube, and you need a mastic gun for it, then personally I wouldnt use it for cracks on walls, I have never used it on walls/ceiling in any of my jobs.
Its used mainly for above skirtings, frames etc.

Any powder filler will do, dont buy the readymade one in a tub or tube, its awful to sand down, just mix up the powder one with water, and fill the cracks, after you have opened them up of course.

Leave to dry, then sand back, so its now flush with the wall, making sure there is no indent, if there is, then fill again and sand, run your hand over the filler, and if it feels flush with the wall then its okay.

Just before you start your rolling, knock up a little thinned emulsion, (the colour your going with) and brush on the filled areas, when dry, do it again, I normally do this 2-3 times before I roll, this will stop the white filler from flashing thru your finished coats, as in some lights and angles, you will see where you have filled, doing what I suggests eliminates this.

Let me know how you get on.:D

nickj_2

i use this and it's easy to sand down

https://www.toupretpro.co.uk/products/product_view.php?pid=11