I'm skimming a living and dining room, the walls are currently in good condition but still need a skim. They look to be plastered then painted with silk finish emulsion. How would you go about preparing these walls for a skim? Do they need scoring up so the new plaster bonds to the silk finish?
I think I'd be very wary of skimming straight on to this. At the very least it would benefit from a keying using ~300-grit sandpaper, but then there's possibly a risk of the water in the skim going through theses score marks and lifting the paint. So, I'd personally chust make sure it's clean (sugar soap?) and then give it a coat of Everbuild Blue Grit or similar first. This will turn almost any smooth surface into one perfect for skimming over. It ain't expensive either - one 10L tub should do around 45m2
Everbuild Blue Grit very good, unlikely it's needed. Available from TS. http://www.everbuild.co.uk/image/data/FEB COSHH TECH/Blue Grit User Leaflet.pdf
I personally wouldn't skim straight on to vinyl silk as there's a genuine risk of the paint bubbling up in places, or even the skim not adhering to the shiny surface as well as I'd like. Ok, the chances are it'll be fine. But what a risk to take! Is it anyone's fav job to scrape of patches of unattached skim? PVA is a possibility, and I've certainly used this myself in the past, especially when there were patches of emulsion paint left behind. Mind you, that was always matt emulsion, not silk. I reckon there's a fair chance you could scrape/peel dried PVA off a good quality silk emulsion surface. So, for the little cost involved and the virtual guarantee on a great job, why wouldn't Steve Blue Grit it?
It was my reply to the OP but has appeared wrongly..... read it again: Why would the walls need a skim if they are in good condition, sand over the silk with 120 grit, wash the walls with sugar soap and line the walls with a good quality lining paper. This is more economical, less messy and a lot quicker.
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