Our 1930's semi is due the landing and hallway plastering, currently painted in an almost gloss finish paint (you can wet wipe it with a sponge and the water just runs off it)

Been told we will need to prep it first for the new plaster to bond to - any recommendations on a cheap-ish (only going to be used to prep these walls) random orbital sander to get?

Or any other way to prep it?

Unibond?

Sure we had a tiled bathroom overplastered one time and just applied unibond prior to getting it skimmed

If the paint and underlying surface is sound, paint over it with watered down PVA glue, works fine, I suspect unibond is the same. BMW i3 Electric Car
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Agree with above, though it wouldn’t hurt to clean with diluted sugar-soap prior.

I usually apply PVA same day as skimming, but make sure it’s not still wet

There is a specifically made product, Blue Grit, which will work on a multitude of poor surface before skimming if you don't trust PVA, which can peel off gloss walls...

https://www.everbuild.co.uk/product/febond-blue-grit/

Have you done a tap test all over the wall, if the sand/cement layer has blown off the bricks/blocks then you may not notice if it has a lot of gloss paint on the surface, it sort of sticks the wall together... knock on it and listen for any hollow sounding areas... if there are more than a few small isolated areas it maybe better to hack all the old plaster off and start again, although that can be a can of worms as well...  Pete
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On a house of that age, you can guarantee if you hack off any area of plaster you will open the proverbial can of worms.....

Cheers all

And andy S - you were right, pulled off the door architrave last night and half the plaster came off too! Brittle as hell - looks like its going to be a bigger job that I first thought

I would personally scratch it all up then PVA.
Have used the gritty PVA too (which you have to keep stirring btw) which worked well.
Either way I'd personally scratch up the paint using a rough 20-25mm cross hatch.
The PVA will then soak beyond the gloss and inter-connect

If you are getting a plasterer then I'd leave it to them to advise.
. Cheers, Greg
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+1 for 'Blue Grit'. Used it before and never had any issues with the new plaster blowing etc.

Much easier and faster than the other options in my opinion.

The best solution is British Gypsum Thistle Bondit.

Made specially for low suction walls and contains grit.

https://www.travisperkins.co.uk/plastering...lsrc=aw.ds

Ignore the price and get a quote directly from the supplier. (That’s just TP’s over optimistic pricing....) There is nothing that can't be fixed with a hammer😜😜
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