New plaster sealer? recntly blocked a small alcove in a wall (16 x 18 (41cm...

recntly blocked a small alcove in a wall (16 x 18 (41cm x 46cm). It say on the tub of readymixed plaster that before sculpture I should seal the plaster using, funnily ample, a plaster sealer. I'm not tight but it seems silly to wages lb12 for a small can when I'll hardly uses any of it and can't verbs any other occassion when I would use it.

Can anyone think of another opening of sealing this i.e. watered down emulsion or anything ?
I hold a ripened Heywood Wakefield dresser that...
Answers:    My gramps is a plasterer and after he re plastered my house he told me to paint over it near watered down emulsion paint. 1 part paint 2 parts wet.

We sealed the kitchen wall beside watered down PVA, and when we painted it the wallpaper started peeling past its sell-by date like wall weekly after a couple of months so steer clear of PVA :)
Block boil from my pane?
I do a fair bit of plastering and i find it cheaper to use pva epoxy resin watered down , when its dry it seals the bright plaster. hope this helps.