Glue trouble

[John Brown]

Yesterday I attempted to glue two 1.8m lengths of Douglas Fir, 18mm thick by about 200mm wide edge to edge with Everbuild 502.
Just went out to the shed(after a good 16 hrs), and was able to fairly easily pull them apart.
Now I'm wondering what went wrong. I don't think it was that cold in there overnight.
I gues that bottle of glue could have been damaged by low temperatures earlier this year, although I didn't think I let it get that cold. The Douglas Fir is fairly green and wet, but I thought the 502 was OK for that - better than standard PVA.
Any advice or theories?

 

[MARK.B.]

Possibly a combination of colder temperatures and the green/wetness of the wood ,how old is the glue ? . i was a bit suprised when i looked at the temp gauge in my workshop last week and the temp had fallen to 1.2 C at some point during the night.

 

[Ttrees]

I do glue ups in the house when it's cold at this time of year,
Leaving parts to warm for a day or more is a good idea, glue always stored in warmish place, aswell as having the work well up off the ground when gluing maybe necessary, the higher the better if you have a cold house.
A bit of mesh for a table with an oil rad underneath and a blanket maybe a good idea.
Might need to periodically run a sopping rag over the timber for some species to avoid splits doing this.
That's for laminating narrow timbers.
Can't say I've ever glued a wide panel doing this, so would be wary and use some cleats for the job, and probably not try and get it done quickly, i.e leave for a few days to acclimatise instead of using the quick oil rad approach.

Good luck for the next time round, at least it didn't only half bond.
All the best
Tom

 

[Doug71]

It most likely failed because the wood was too wet. Try PU glue, that actually cures better when there is a bit of moisture present.

 

[EddyCurrent]

Low temperatures will spoil the glue.
There's this post here with the same problem, Glue failure on douglas fir

The only glue I use these days is Titebond, Axminster tools have decent prices on it.

 

[John Brown]

Glue is maybe 4 weeks old.
I thought 502 was PU, that's why I bought it.
Anyway, I'll give it another shot with Gorilla glue.

 

[Sgian Dubh]

Now I'm wondering what went wrong. I don't think it was that cold in there overnight.
The Douglas Fir is fairly green and wet, but I thought the 502 was OK for that - better than standard PVA.
Any advice or theories?

How cold? If it was below about 10 deg C is too cold.

Secondly, how wet? The wood needs to be dry and that means below 20% MC. All adhesives, except polyurethane types, will fail if the wood is wetter than this. A sure sign of failure through excessive moisture with PVA type adhesives is that the failed glue line will show as chalky and crumbly on the mating edges or faces.

Chalky and crumbly will also show if the wood and the air temperature was too cold.

It's a symptom of both failure modes, so it could be caused by either fault or both of those faults together.

As mentioned here and by Doug71, polyurethane adhesives will work with wet wood, although the ideal MC is about 8 - 10% MC rather than 20% MC or greater. Cold can cause problems with polyurethane. This last paragraph is supplemental information and not relevant to your specific glue failure experience. Slainte.

 

[John Brown]

So what's a good polyurethane glue? I bought the Everbuild 502, believing it to be PU, but looking at the bottle, it makes no mention of PVA or PU. Likewise the bottle of Gorilla wood glue.
I'm happy to buy more glue, and I probably need to chuck all mine out. I have Titebond III that must be pushing 15 years old.
The Douglas fir is fairly green, and fairly wet, I can't do much about that, but I can certainly raise the temperature a bit.

I'm trying to get a wide enough piece for the aprons on my work-bench built from leftovers.
I know Paul Sellers uses 40mm by 250mm or something, but I am struggling to find anything that big round here.
Maybe if the Bristol wood recycling place was open I might get lucky.
Alternatively, I was looking at new scaffold boards, but the only ones I can find without metal end straps are B and Q, and although they list them(and at a good price), they don't appear to stock them.

 

[Doug71]

This stuff from Toolstation will be okay.

https://www.toolstation.com/polyurethane-wood-glue-750g/p52489
Don't get it on your hands and don't try wiping off any excess, best to wait until it's set then cut it off.

 

[profchris]

If it's wet it won't half move around as it dries. Maybe find some wood better suited to the task?

 

[John Brown]

If it's wet it won't half move around as it dries. Maybe find some wood better suited to the task?

Yes. I have tried.
I'm on a budget here. Things are tight until we sell our previous house. But I have things I need to build.

 

[Sgian Dubh]

Everbuild describe their various formulations of adhesive, such as their 502, D4 type, etc as a resin adhesive. That's basically code for saying it's a form of PVA or an aliphatic resin, with additional additives to create specific performance characteristics. Chuck the Titebond III out. It's beyond its use by date, and glue is cheap in the wider scheme of things.

As to polyurethane adhesives, look for a description stating it's polyurethane adhesive, whatever the brand.

You say your Douglas fir is fairly green and wet, but the question still remains, how wet? If it's more than 20 - 25% MC now, unlikely I suspect, unless you've managed to source some boards that haven't been seasoned. Anyway, if it is as wet as, say, 20% MC+ you're likely to experience movement (shrinkage) problems in the future because it's really too wet to build a workbench. If the stuff really is that wet you ought to let it dry further to maybe 12 - 14% MC before using it. A bench in a relatively cool and damp workshop is likely to hover somewhere near those MC figures anyway.

You could always test your wood before using it to find out its moisture content. A pin or pinless moisture meter would give you a reasonable idea of MC, but you could also undertake an oven drying test for wood MC if you need to know the wood MC very precisely - unlikely I guess. Slainte.

 

[TheUnicorn]

I use soudal pro45p, which I stumbled upon when looking for a cheaper alternative to gorilla foaming adhesive Amazon.co.uk there seems to be a general idea that the foam (in U foaming glues in general) is great for filling in gaps in the glue up, not the case, if it is foaming it is filled with air and so is no stronger than expanding foam. get nice tight joint / joins and clamp well, leave for the foam squeeze out to harden completely, then scrape off.

 

[TheTiddles]

Gorilla white glue is nice to use, quick to set. They also make a PU which is very different stuff and will do the usual thing that PU does and stick to most things even when they’re wet.

If your material is actually wet still, I’d sit on it for a bit as it’ll only go wrong. Unless you’re making outdoor things

Aidan