Cracks in new plaster - how to repair

[CarlaW]

I recently had my living room skimmed. The house is around 80 years old and as such the plaster was in quite bad condition before. We had a professional plasterer around who skimmed over the old plaster in most places and only in a couple of areas did he go back to the brick work. The work was done in January and we left it a good few weeks before considering painting. Before painting a few hairline cracks appeared that I filled in with pollyfiller. However since painting these have reappeared (and more) and seem to go on forever. I have again tried to fill and yet again they have reappeared. Some of the areas around the cracks sound hollow leading me to believe the plasterer should have gone back to the brick work in more areas than he did. My boyfriend thinks the cracks are just due to the age of the house however I am more inclined to think that the plasterer hasn't done a particularly good job. We have a lot more rooms to decorate in the house so would really appreciate some advice to try and avoid the same happening again. I would also appreciate any advice on how to repair the cracks once and for all.

Many thanks.

[DUDE DIY]

Hi there in a property 80years old theres always going to be a few hair line cracks and imperfections. So your boyfriend is kinda right....The only way to get rid of them all is to completely re-new all the plaster in the house but even that doesn't garauntee your walls will be hairline crack free and perfectly flat. Over time dust can get behind old plaster causing large sections to form hairline cracks and sound hollow or plaster can blow away from the lathes ( how it was originally attached when the house was built ) and sometimes its simply just old! Modern central heating also plays its part. As for the plasterer doing a good job, did you ask him to check the entire room for all effected areas which need to be taking back to the brick?....did he dust proof the walls before he plastered?....sometimes working on a room and decorating can cause old plaster to loosen and form these cracks....as for filling these cracks for good you will need to cut a 'V' shaped channel along these cracks with a sharp blade taking care not to make the problem worse and fill with a good quality flexiable filler. Hope this advice helps.....dude diy