stain block

[Tom]

Hi All,

I need a small amount of stain block to cover some water damage to a ceiling (have been told this by a builder) - but it costs the earth and is sold is large tins or as a spray at my local B&Q - can I use universal primer instead (the spirit based non-acyclic version). Would universal primer work as well as stain block?

Alternatively what else could I use instead that would be cheap?

Tom

[Steve Walker]

Any solvent-based paint or varnish should stop a water stain coming through.

[Jason]

Try B.I.N stain killer available in 390ml tins up to large size and in a spray

alternative is an oil based paint such as gloss.

Good Luck

[Cash]

Use diluted Unibond on an area slightly bigger than the stain and then paint with a couple of coats of normal emulsion paint - very successful in my case.

Cash

[F Murtz]

shelac can work.

[1501]

Dilute some PVA adhesive and slosh it on. Worked for me.

[pete]

I used some of this stuff

few years ago. It comes in 750ml cans and (IIRC) cost about £10. I don't recall where I bought it, but since the only non-trivial outlets around here is B & Q, I guess it was from there. It did the job, but needed 2 coats to completely cover some badly (as in job done badly) stained redwood in the conservatory.

[stuart noble]

Oil based paint (matt or gloss) never fails for me. It should be something that has zero affinity for water, which rules out spirit based coatings, like shellac and, obviously, pva.

[Phil L]

Any oil based paint, either undercoat, eggshell or gloss, of any colour will stop water stains. Wait for it to dry then paint over with normal emulsion.

[NT]

The trick to stain blocking is to alternate paint solvent types. So a layer of oil based then a layer of water based etc. A layer of oil based household undercoat will block most stains with emulsion each side of it - but not all. If blocking doesnt succeed at first, try more alternating layers or try something with another type of solvent base. The main downsides of using oil undercoat is the long dry time. Also sometimes you'll need more emulsion coats to get a decent covering, oil paints can be a bit water repellant.

NT