Rippled skim coat on ceiling?

I've have chipped and scraped the layers of crap off my bathroom ceiling, paint,artex, paper, paint in that order... The surface is a tad patchy to say the least. Some bits are paint, sone plaster some plasterboard. I gave it a coat of pva (diluted) but for some reason the test area of skim coat (practising - I'm no plaster yet). ;-) was a bit uneven.
Went on ok but was very rippled - like a beach where the waves have ridged the sand. I've patched walls elsewhere and made a pretty reasonable job of the skim coat so have to put it down to the surface.
It looks like some areas have dried as they would on plaster etc. but the patches of paint were "wet" so weren't drying at the same rate.
This is strictly a practise ceiling but I didn't want to faff about removing the plasterboard, moving the loft insulation and all the messing about that involves.
Would a neat coat of pva be better to cover/prepare the patchiness or give up and stick up a new layer of thinner plasterboard over the top and skim that etc. ?
Mark S.
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It's difficult to know why you've ended up with ripples. I wouldn't have thought you'd need to have them if you'd finished the plaster properly. Did the ripples come as the plaster dried, or where they there when you'd gone as far as you could? If the former, maybe putting another plasterboard over it and starting again would be best. If the latter, try skimming over it again, making sure you get it ripple-free.
Rob Graham
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On Thu, 6 Nov 2003 14:28:12 -0000, "robgraham"

To prove a point to myself I went and skimmed a bit of artex on the stairs with the other half of the same batch and that was fine, didn't finish it or anything as the artex is being hacked off eventually.
I'm going to neat pva the ceiling and try again tomorrow as an experiment as someone emailed to suggest.
It's not a huge bathroom so the plasterboard route wont' take that much work, he saidd with fingers crossed. ;-)
Mark S.
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I've never seen this. Is the plaster coat too thin and therfore saggy ?
Infact i've not had much success with plaster, full stop.
For patching reasonably small areas I usually use polycell premixed skim coat, which goes on a treat with very little sag as it is less sloppy. This just needs the tram lines sanding out afterwards and has a very smooth finish.
Cheers,
Paul.
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On 7 Nov 2003 07:28:33 -0800, snipped-for-privacy@technologist.com (Zymurgy) wrote:

I've figured it out now it's dry and daylight... it's where the ceiling has been scored in the past presumably to put the artex up. The plaster dries really quickly where the score lines are but at a slower rate on the rest. So as you go over it the wetter bits are getting dragged out and the drier bits being built up or something like that. It's my first bit of ceiling skimming so live and learn. :-)
Mark S.
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