PVA, and 'The Other' PVA

[jkn]

Hi all - slightly stupid question perhaps...

I see plenty of reference here re. the use of 'PVA' as a sealer. I have some myself, a 5L container of 'Contractors PVA' bought from Toolstation or similar and used for a few general projects around the house.

Until recently I thought that this PVA was just an industrial version of the same "PVA glue" you can buy in stationers, supermarkets etc, as a paper glue, and in DIY shops as a wood glue.

But I now realise that they have (or tend to have) different chemical formulations. For a start, you can't use Contractor's PVA to make children's slime. Disaster!

Looking into this a bit further:

- PVA glue: Poly Vinyl *Acetate*

- Contractors PVA sealer: Poly Vinyl *Alcohol* (I think)

My question is: Can 'PVA glue'(Polyvinyl Alcohol) also be used for all of the sealing uses that are discussed here, or should I only use 'Contractors PVA'(Polyvinyl Alcohol) for these purposes? I realise there is a cost difference, its the functional difference I am interested in.

Thanks a lot, Jon N

[The Natural Philosopher]

Ni. Its just dilute Poly Vinyl Acetate

The sealant stuff is more dilute and a lot cheaper than the glue otherwise there is zero difference IME

[jkn]

Not true, I think. See eg:

{{{ Polyvinyl alcohol is extremely soluble in water for reversibility and remains flexible as it ages.

Also known as PVA, not to be confused with Polyvinyl Acetate adhesive, Polyvinyl alcohol adhesive is said to be somewhat more reversible than PVAc (polyvinyl acetate).

Polyvinyl Alcohol (PVA) liquid 15 % in demineralised water. Can be used for: Modification of dispersion glues, manufacture of paper glues and glues which can be remoistened. Protective gel for the emulsion polymerization, raw material for finishing and textile glaze, binding agent for the surface processing of paper. }}}

Also see my evidence that only 'PVA Glue' can be used to make children's slime - and it's not just because of any dilution differences

[newshound]

Poly vinyl alcohol is soluble in water, poly vinyl acetate is not.

I am pretty sure that the "industrial" stuff will contain both, the "domestic" might just be an emulsion of the acetate, or might have a much lower proportion of the alcohol.

[The Natural Philosopher]

They tend to change into each other anyway.

[Fredxx]

This is something I have looked into as well and find the subject confusing. Many recipes mention Elmer's glue which according to:

Polyvinyl Acetate. The wiki entry for Elmer's glue isn't helpful.

says, "PVA is prepared by hydrolysis of polyvinyl acetate", which if you look up is generally with Sodium Hydroxide.

Most slime recipes suggest borax, or sodium carbonate or sodium sesquicarbonate.

I'm therefore wondering if the glue recipes are actually where start off with PolyVinyl Acetate and end up with PolyVinyl Alcohol.

To confuse things further I believe the PVA from building type merchants is PolyVinyl Acetate with PolyVinyl Alcohol as a thickener.

BICBW

[TimW]

I had no idea. I am working my way through a large pot of cheap building PVA using it as wood glue. It seems a bit runny, it's nice and slow to go off, and obv it's soluble so only for dry indoor use. Is there something wrong with it? TW

[jkn]

Hi Tim not quite sure what you are asking...

I know that you can use the 'contractors PVA' as a glue - that's partly what it is sold for, after all. As well as a sealer I have also used it as wood glue and for bookbinding.

My question was more the other way round - using the 'Wood Glue PVA' as a sealer - and also the more general question about the chemical differences between the two types.

J^n

[Brian Gaff (Sofa]

You mean it does not mean Pumpkins Via Air? Brian