Effect of Cold on PVA Glue

[AndyG]

Hello All,
This is something this been worrying me for a while, so thought I'd see what everyone's opinion was.
I've noticed that when using PVA glue in the cold it tends to set very white instead of clear.
After the first time this happened, I went out and bought a new tube, and the whitening effect occurred overnight on the piece I'd just glued with the new tube.
I'm just wondering if this is going to be a problem, do you think it effects strength?
I might move the tube into the house for a while, then try gluing something up indoors, to see if the effect is reversible.

Andy

 

[Jarviser]

I am pretty sure that PVA polymerises when it sets, which is a chemical reaction, so there is probably a minimum temperature for full curing. My bottle says between 5 and 30 degC. Maybe if it is too cold it dries before it can fully polymerise? I have noticed that the blob on the bottle nozzle stays white in the winter. Sounds like a controlled experiment with some test pieces would be useful.
I also noticed that if a bottle freezes, the thawed glue is completely useless.

 

[Offcut]

I have had the same problem with titebond. Goes white when the temperature is too cold. Apart from yesterday the temperature in my workshop hasn't been much above 5deg :shock: usually around 3deg - been a problem gluing up.
You'll find if you do a couple of test glue ups, the joints break apart easily when the temp is too low.

Andy

 

[Scrit]

Hi Andy

PVA (and aliphatic resin - same thing, Offcut) is water-based and must never be allowed to freeze as the ice crystals destroy the long chain starch molecules within the glue (and PVA is essentially a modified starch). If that happens it's all scrap as Jarviaser says. The whiteness you are talking about is called chalking - in many PVAs this occurs somewhere 3 to 5 degrees Centigrade and in that state the glue ceases to be an effective glue and the joint will be weak or defective. So when glueing-up the workshop must be warm and the workpieces, too - that's why a lot of trade places traditionally did their glue-ups in the afternoon - and the joint needs to be kept warm during the initial close time.

Hi Jarviser

You are confusing cross-linked with "ordinary" PVAs. A cross linked PVA, sold as D3 (British grade) / Weatherproof / Exterior grade, is designed to react chemically as it sets. the cross-linking of the molecules is irreversible. An ordinary PVA, such as D2 / Interior grade, does not cross-link at all, and can be reactivated by the application of heat and moisture - sometimes useful, although such glues show a tendency towards creep (D3s do not)

Scrit

 

[PowerTool]

At work,we move various glues in bulk (27 tonnes at a time)
Acrylic/acrylamide dispersions and solutions all fall into the same category - not temperature-sensitive as such,but frost-sensitive.
They all have to be kept above +5c,so we do sometimes have to heat them (with tempered water) in winter

One of our regular deliveries is to a door manufacturer/supplier in Barnsley,who get a government grant to employ East European immigrant workers;driver was delivering there once when their storage tank overflowed - operator was driving the forklift at the time (when he should have been supervising the discharge) panicked,dumped a pile of pallets on the floor in the spillage and was last seen running out of the yard and across a field :lol:

When the driver was ready to leave,had to get someone to chip the pallets loose,as the glue had set...

Andrew

 

[matt]

Hi Andy

PVA (and aliphatic resin - same thing, Offcut) is water-based and must never be allowed to freeze as the ice crystals destroy the long chain starch molecules within the glue (and PVA is essentially a modified starch). If that happens it's all scrap as Jarviaser says. The whiteness you are talking about is called chalking - in many PVAs this occurs somewhere 3 to 5 degrees Centigrade and in that state the glue ceases to be an effective glue and the joint will be weak or defective. So when glueing-up the workshop must be warm and the workpieces, too - that's why a lot of trade places do their glue-ups in the afternoon - and the joint needs to be kept warm during the initial close time.

Hi Jarviser

You are confusing cross-linked with "ordinary" PVAs. A cross linked PVA, sold as D3 (British grade) / Weatherproof / Exterior grade, is designed to react chemically as it sets. the cross-linking of the molecules is irreversible. An ordinary PVA, such as D2 / Interior grade, does not cross-link at all, and can be reactivated by the application of heat and moisture - sometimes useful, although such glues show a tendency towards creep (D3s do not)

Scrit

Scrit, I've read a few of your posts and you seem to just know stuff! Don't s'pose you have an ethernet connection somewhere about your person via which we could connect you directly to the www? :wink:

 

[PowerTool]

Scrit, I've read a few of your posts and you seem to just know stuff! Don't s'pose you have an ethernet connection somewhere about your person via which we could connect you directly to the www?

Chances are,it would need an inverter - I bet he's 3-phase :lol:

Andrew

 

[Jarviser]

.

Hi Jarviser

You are confusing cross-linked with "ordinary" PVAs. A cross linked PVA, sold as D3 (British grade) / Weatherproof / Exterior grade, is designed to react chemically as it sets. the cross-linking of the molecules is irreversible. An ordinary PVA, such as D2 / Interior grade, does not cross-link at all, and can be reactivated by the application of heat and moisture - sometimes useful, although such glues show a tendency towards creep (D3s do not)

Scrit

Thanks for that Scrit - I was nearly right! I had no idea the two grades were so different. I thought they both suffered from creep too.

 

[Buckeye]

I noticed my glue ups were very white the last couple of week so after doing a couple of glue ups last night I brought them in the house to dry

 

[AndyG]

Thanks all for your input. There's some great knowledge there. Looks like I'll be off to B&Q again for yet another tube of glue (to be kept inside). That, and a lot of scrap newspaper for the kitchen table!!

This is probably a question for another thread, but what other types of glue do people use for everyday projects? I use Evostik PVA (like the one below) because that's what my dad always used and I've never thought of trying anything else. Would be interested to here of some alternatives though.

Thanks again
Andy

 

[Jarviser]

I mostly use the green stuff like you, and have made toys and small boxes with rebated butt joints without nails that have never failed.
The good thing about its tendency to creep is that, for instance, when I made a surprise trinket box for SWMBO in December, the mahogany was of quite high moisture content. I couldn't bring the wood inside to dry out as it would have given the game away. I glued the lid and base onto the sides with standard PVA. As the box dried over the weeks in the house, the lid did not split, but crept inwards leaving the top about 1/2mm from the edge. Later that year I took it to the workshop for a plane-up of the front and back and repolish and she was none the wiser.

Now if I make traditional stuff like an oak stool where the legs are mortised through the top I prefer hide glue. If I had used it on the box the top would have split.

 

[Wanlock Dod]

Andy,

I also use the same glue (as you) for pretty much everything, although I love epoxy for non-wood stuff. If it works why fix it? Mind you the only finish I ever use is Danish Oil.

Dod

 

[AndyG]

I glued the lid and base onto the sides with standard PVA. As the box dried over the weeks in the house, the lid did not split, but crept inwards

So, PVA allows movement even after it has 'set'?

If it works why fix it?

Well indeed. Just going to have to be a little more careful with where I store it in the future!!

 

[Jarviser]

So, PVA allows movement even after it has 'set'?

The indoor PVA does, if the joint allows it, very very slowly typically over weeks and months, which is why it is called 'creep'. Depending on the joint it may be a good or bad thing.

 

[devonwoody]

I expect you have noticed that I do my winter glue ups in the kitchen, looks like I was taking the correct action for once.
I use the blue bottle version, does that mean it should not creep?
l also I purchased a new bottle this week from a builders merchant and I would not have thought their showroom this winter would have been over 5C at night. Does this mean I will have problems?

 

[Jarviser]

I use the blue bottle version, does that mean it should not creep?

I think Scrit answered it, assuming that the blue one is D3 grade.:

An ordinary PVA, such as D2 / Interior grade, does not cross-link at all, and can be reactivated by the application of heat and moisture - sometimes useful, although such glues show a tendency towards creep (D3s do not)

I would not have thought their showroom this winter would have been over 5C at night. Does this mean I will have problems?

The way I understand it you should use it above 5C, but store it above 0C. If it has ever frozen I think you will find it will have "curdled" i.e. separated into clear liquid and lumps. That is what happened to mine.