PVA glue separates in the bottle

Don Case

Don Case

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I've noticed that my PVA kind of separates. It's like the white part settles out. Looks like unstirred pearl paint. I normally transfer glue from the one liter bottle into a one or two once bottle for use. It only seems to separate in the one liter bottle and it's a bit of a pain to get it mixed up again. Is this a bad thing? It seems to still work but I'm concerned that I may be getting a weaker joint. Does it have to be really well mixed? There is no mention of this on the bottle.
 
If it's mixed it works fine. I'm just not sure if I have to concern myself with a good mix when I transfer some to my small bottles. I can mix it, just wondering if anyone else had noticed this.

Oh, it's Natura White Glue. Home Hardware's house brand.
 
Don Case said:
I've noticed that my PVA kind of separates. It's like the white part settles out. Looks like unstirred pearl paint. I normally transfer glue from the one liter bottle into a one or two once bottle for use. It only seems to separate in the one liter bottle and it's a bit of a pain to get it mixed up again. Is this a bad thing? It seems to still work but I'm concerned that I may be getting a weaker joint. Does it have to be really well mixed? There is no mention of this on the bottle.
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How old is it? Has it been in a cold room? Shake it also. But replace it because glue is cheap.
 
Don Case said:
It's about 6 months old. It's been coldish but not below freezing. Strange that there is no storage instructions on the bottle.
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When itcomes to PVA glues, I prefer Titebond glues. They typically have a two year shelf life. Mine hang in there even when my shop gets in the 50's. But no project is worth the risk of having the glue not perform to standards. My opinion. I start new projects with new glue. But thats just me.
 
If in doubt, chuck it out!
Wood glue (not PVA) has a shelf life of around 4 to 6 months if kept cool and well sealed.

PVA glue apparently has no shelf life. On the other hand PVA glue is reasonably cheap and why invite disaster when the glue, due to its seperation or age, no longer does the job efficiently.
That's just my opinion.

I got curious and had a look at the Henkel website for their product Ponal, a PVAc glue. One can download the technical data sheet where the product details are listed. They do not mention any shelf life on this sheet.

Titebond give for their general wood glue a shelf life of 24 months. http://www.titebond.com/App_Static/literature/ff876_ShelfLife.pdf

Trevor
 
A simple way to keep it from separating is to rotate (turn upside down) the bottle several times a month.
This is how I maintain my glue.
 
This can happen with poor quality PVA glues. Actually it's not strictly a glue thing. It happens with any water based emulsified compound, where you mixed a liquid with solids to make a high viscosity compound.

ALL PVA glue will eventually separate, if you wait long enough. Key rule is; the smaller the solid particles you are using the longer they stay suspended in the liquid. That's because, the smaller the particle, the less it weighs and the less effect gravity has on it and the longer it stays suspended. The reason you see in in cheaper PVAs separate sooner is the manufacturing company tries to save costs and do not spend the time to grind the solids into fine enough particle size. Keep in mind, the smaller the solid's particle size the stronger the adhesion properties as well.

This phenomena may not be the reason for separation in all cases, but it is the most likely one.

I love science!!
 
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I would contact the manufacturer and speak or email their chemist and ask his opinion. Go straight to the sauce (pun intended)
Their address is usually on the label and or their pdf for the safety document for your product.

Best Regards Malcolm Armour
 
LuigiSoft said:
PVA glue apparently has no shelf life. On the other hand PVA glue is reasonably cheap and why invite disaster when the glue, due to its seperation or age, no longer does the job efficiently.
That's just my opinion.
Click to expand...

I agree here with Trevor.
I would not take a risk, that the glue is not 100% working. Maybe the bottle got some irregular heat or higher temperature before you bought it.
Wood glue is relatively cheap and you do not need mass of it - buy a new one (maybe smaller bottle) and this one is for the garbage
For contacting the manufacturer (often in more expensive cases a good idea), the necessary time to discuss is better used for ship modeling ;)
 
There is no address or MSDS on the bottle and a Google search of the name just takes me to Home Hardware's sales site. This is like so many of the items in big box stores. They buy from a supplier who buys from a supplier who buys it from China. Trying to get any info is like pulling hen's teeth.
 
My garage rarely, if ever, gets below 40f and the glue is stored on a warmish wall so I'm pretty confident it never froze. It's not clumpy. I've tested the glue a few times since I started this thread and it seems to make solid joints. I hate waste(I'm cheap :) ) so I'd rather not throw it out. It sounds like a few people have noticed the same separation so maybe it's normal. Thanks for the input.
 
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