Sealing chipboard

[cd]

Hi all,

Would it be ok to seal chipboard with PVA and if so, at what ratio to water, number of coats etc? This is piece will be going under a WC, btw.

cheers, cd.

[Martin Bonner]

Make sure it's waterproof chip in the first place! It's not that much more expensive.

Note: "Waterproof" is not the same as "suitable for building a swimming pool" but it should be OK under a WC.

[stuart noble]

+1

[Andrew Gabriel]

Set PVA is water soluble, so that won't work.

Is the aim to handle bad aim ;-) or a potentially leaking toilet? Bathroom flooring grade chipboard (usuaully with a faint green stain) will not rot when it gets wet, but it will probably still soak up piss and smell.

[cd]

Flawed logic at work here, I think. Just because PVA can be diluted with water doesn't mean it remains water soluble after having been brushed on and had the chance to dry out. If that were true, half the exterior masonry paints you can get would be useless.

It's just in case of a puddle should a plumbing joint start to fail whilst I'm away on holiday or such like; that's all. I wasn't even aware there was such a thing as waterproof chipboard TBH. I've used regular chipboard and pva'd it thrice. Looks nice and shiny and should do the trick. :-)

[Andrew Gabriel]

You are right that just because something can be diluted with water doesn't mean it's water soluble once set, but you are wrong to say PVA is not water soluble once set, because it is - it causes the polymer to slowly break down into acetic acid (which itself can go on to damage some other materials in contact with the PVA).

If you want a similar product which is not water soluble once set, that would be SBR.

PVA also supports mold growth, which might be an issue if used in a humid/moist application.

[stuart noble]

A lot more than half of them ARE useless.