Use Oil-based Undercoat as a Stain Blocker

so final tip when you're painting somewhere where there's been a stain whether it's water damage or a kitchen where you've got oil splatters and any kind of stain felt tip on the wall markers permanent marks on the wall um they obviously come through emulsion paint water-based paint especially and they're really hard to get rid of you can go to your hardware store and pick up stain blockers there's loads of different brands in england there's polycell zinter bin all those kind of stain blocks and they're quite expensive my tip is that normally as a decorator i'd have a tin of oil based undercoat on the van this is obviously for when i'm undercoating and i keep it on the van because that itself is a really really good stain block and it's obviously a lot cheaper than your normal stain block and if you are decorating a house and you do come to undercoat these curtains you'll have a tin of undercoat anyway so if you do find a water stain on the ceiling a mold stain felt tip like i said permanent marks on the wall you'll have to obviously wait a couple of hours for it to dry properly because it's oil-based but it saves you going out to the hardware shop or your local diy shop and buying a new load of paint that you don't need because obviously you're not going to use a big tin of stain block on one small stain so um there you go