skimming over blown plaster

[2zanzibar]

Hi all, I've got a small bathroom ceiling to replaster. There are 2 problems:

1) The old skim has blown in a few places, but the ceiling itself seems stable (looks like concrete),the blown plaster patches are about 2mm deep, so not deep.
2) The ceiling was never painted but instead given a clear glossy varnish (the client reckons it was unibond, and she wants it reskimmed and varnished again so it 'looks like' venetian plaster)

I'm a decorator with some experience of plastering, but not with a ceiling like this. My question is once I've scraped the blown plaster and pva'd it twice, can I reskim the whole thing in one go or do I have to fill the patches up first with bonding and skim next day?

the 2nd question is what do I seal it with bearing in mind it's a bathroom? Just a waterproof PVA? Zinsser have this clear sealent called Gardz, wondering if anyone's familiar with it? Any advice will be welcome.

 

[johniosaif]

It depends on what thickness needs re filling in the plaster coat, I would scrape off all that comes of,gyp bond or similar, if its a bit rough put two handfuls of bonding in the first coat,flatten,let it pull in then skim with a nice skim coat,

 

[SpankySouthport]

Scud it

 

[2zanzibar]

The thickness is around 2-3mm. I'm hoping to do this in one day, ie., to scrape off loose stuff, PVA it and reskim it, then seal the whole thing a week later. I asked a plasterer about it the other day and he thinks it should be ok....so here goes!