On 25/10/2020 12:19, jkn wrote:
On Sunday, October 25, 2020 at 12:03:30 PM UTC, The Natural Philosopher wrote:
On 25/10/2020 11:19, jkn wrote:
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)
Ni. Its just dilute Poly Vinyl Acetate

Not true, I think. See eg:

https://www.preservationequipment.co...cohol-Adhesive

{{{
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


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.