Stain block paint

Are proprietary 'Stain block' paints any better than oil-based undercoats?

Reply to
Jim Scott
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Can't say i've ever used an under coat for stain blocking. What I do use is Screwfix's spray stain block, which is very easy to use and drys quickly. Most likely a lot quicker then an oil based paint.

Reply to
RedOnRed

I first read that as "Satin black". They do more or less what it says on the tin, although I had an uber-stain which required three coats of the Aquaseal product to kill it.

John Schmitt

Reply to
John Schmitt

Reply to
Rob Morley

Skid marks :o)

Nah; really water marks on the ceiling after a roof leak.

Reply to
Jim Scott

Presumably for blocking stains.

Reply to
RedOnRed

I have used the stain block that Screwfix sell to cover water marked plaster. I found the yellowing stain came through the stain block as well, which looked suspiciously like normal emulsion to me. Eventually I managed to cover it, but it took several coats of stain block and several more coats of normal emulsion (Dulux trade satin).

Make of that what you will.

Reply to
Fitz

I reckon an oil-based wood primer will take care of that.

Reply to
Rob Morley

What sort of stain, what sort of surface ...

Reply to
Rob Morley

I used Dulux (I think) stain block in the airing cupboard to cover stains from a leaking pipe in the loft. Initially applied normal Dulux matt emulsion but stain came back. Used stain block + emulsion and no sign of any stains.

I have also heard this being used to cover nicotine stains as well.

Reply to
Ian_m

Yes. Oil based undercoat will block some stains, stain block will handle more.

NT

Reply to
bigcat

The only stains I've come across are from old water leaks. I guess the reason they're always brown is either that they carry rust from fixings in the masonry or oxides from the bricks. Maybe John Schmitt can enlighten us on that. Any oil based paint will block these, but any water based coating won't IME.

Reply to
Stuart Noble

"Zinnser" (sp?) is very good. I used it over 3 month old creosote which I then white emulsioned, and nothing came through in 3 years!

Reply to
Mr Fuxit

Has anyone used Wilkinson's own brand Stain Block? I use their paint all the time and find the covering power excellent. However the stain block (water based) is still showing the colour through after two coats. I don't really want to emulsion over it until I'm sure.

Reply to
Jim Scott

It is normally hydrous iron oxides from either source carried by water ingress. In short they both count as rust stains. Chemically there is little to differentiate them, although it is a matter of some puzzlement to me as to why these stains can penetrate an oil-based medium. I can only conjecture that the ferric ion complexes with the part of the solvent matrix and migrates in this manner. Iron does some bizarre things, like form ferrocene. My best guess is that the reason for this is that there are only 2 electrons in the outer shell, leaving the 14 in the next shell down accessible thus resulting in this anomalous behaviour.

John Schmitt

Reply to
John Schmitt

I used Zinnser BIN Stain block to cover nicotine staining. A small can which didn't cover anything close to the area written on the tin and the stains also came through again.

Ended up using a wood undercoat and it worked perfectly.

Reply to
daddyfreddy

after two coats.

As far as I am concerned, no water based stain block can be as efficient as a spirit based one. A long, long time ago, I was taught to use shellac knotting to prevent bleed-through, and the only reason I now use Zinsser is that it is slightly paler, and can be used more easily under one-coat paints.

Reply to
Mr Fuxit

I don't think they can, but they do penetrate water based "stain blockers".

Reply to
Stuart Noble

I've just remembered that i've got a tin of Zinsser stain block, which says on the tin "water clear up", which presumably means it's water based.

The actual product i've got is Zinsser Bulls Eye 1-2-3, which is a primer/stain block thingey.

Reply to
RedOnRed

Actually, I can see your product on here...

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looks like they've got quite a good range of stain blockers. I'll have to try and alternative to Screwfix's, which to be honest - hasn't blown me away.

Reply to
RedOnRed

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