Clive wrote:

I'm not an expert on emulsion - but I think the walls in a bedroom
are emulsioned with vinyl silk - there's a slightly shiny surface to
the wall. Now centimetre wide "spots" of emulsion have come off and we
can see the plaster underneath.

Why have blobs come off?
Is it a reaction with new paint?
Or is the plaster falling apart?
I've done 2 ceilings recently where when coating with emulsion straight
over the old paint, the new paint would bubble up. The only cure for
this fault is to scrape back to the plaster and re-paint.
If you try a little patch of paint, to see if it reacts, and it does,
then it may be possible to paint it all over with an oil based
undercoat, let that dry, then emulsion as normal.

Also the old saw of "hairline" cracks. I'm a Tetrion fan - but it
is too thick for these cracks and I'm not keen on racking out bigger
cracks to give a surface for Tetrion to bond to. Has anyone used the
"inverted V" approach where the opened crack is wider "into" the wall
and still narrow on the surface? The idea being the filler won't fall
out. Any success anyone with this? What kind of tool should I use for
raking out?

Unless the plaster is flaky, then it is best to not scrape any more off,
just get a tube of decorators caulk, and rub that in to any cracks.
If they are tiny, then a thick coat of paint should cover them.
Alan.
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