PVA and Polyurathene wood glues

[andycktm]

Thing is ,why do you need minutes to set instead of hour's and why waterproof glue on furniture?

 

[Jake]

For (indoor) furniture, D4 doesn't matter. But this is a woodworking site, and hopefully a bit of a broader church than ukcabinetmaker might be. So sometimes it is very useful.

The minutes rather than hours thing can be very useful indeed, depends what you are doing. I laminated up a bunch of worktops (now to be recycled into a table) from some ex-strip flooring, first into layers three deep. It would have driven me nuts if I'd had to leave each in the press overnight. As it was, by the time I had the next lot planed and thicknessed, the previous bit could come out of the press. Horses for courses. I'd never (personally) think of using it on a trad furniture glue up, where you want open time and the foam would be a nightmare.

 

[Andy Pullen]

PU is brill, I use it whenever possible. the only downside is trying to get the dried foam out of mouldings. I would argue the six month shelf life, mine is much older and still works fine. PU is also less wasteful IMO

 

[johnnyb]

some contrary opinion to say the least. the glue in the test was gorilla glue. it was very scientific at least. no comments on the hign rating of the animal glues especially the liquid hide glue that was nearly the equal of proper hide glue. on certain combinations hide glue was over three times as strong as pu. remember also this has no comment on it waterproofness only its overall strength. just to sum up the article assuming titebond 111 to be the strongest at 100% the other glues were slow set epoxy 99% pva 95% liquid hide79% hot hide 76% and pu 58%

 

[johnnyb]

sorry liquid hide glue was stronger than hot overall!

 

[Pecker]

As stated, PU has little or no strength in the actual expanded gap filling areas. But afaik it has never been claimed otherwise. For normal indoor joinery, I guess i would stick to pva or cascamite, but it's horses for courses. I live a high salt air enviroment with many damp drizzling days. Both the joiners opposite me, and myself have found that for outside work on joints, very little has the strength or longevity of PU.

It would be interesting to compare on different woods, for example on stirling board, which is a resin/wax based board, PVA takes ages to go off, because it is not porous in the traditional meaning of term, so cannot sink into the face of it and bond so quickly. PU on the otherhand goes off in about 10 mins.

I have just made 21 backing frames for an art gallery. Its 2x1 tannalised sawn timber with and 8x4 sheet of pegboard over the top. We made the frames up, ran PU over them, stuck a couple of staples in and hey presto job done and they were totally set in about 15 mins. Pva just wont do that.
That said, when responding to a locksmith callout (I do about 10 a week!), Pva is great for sticking damaged door frames back together. no mess, couple of pins, job done.

And yes, as pointed out, the nice thing about this forum is it's not just joiners/ cabinet makers/ turners/chippies on here. We all have different skills, and so different needs. I learn a lot from others on here as I hope others learn from me - even after such a long post.LOL

Cant beat good old copydex or bostik though :lol:

woody

 

[Steve Maskery]

This is interesting. I've recently bought some Weyroc D4 and it's foamy stuff. We'll see how it performs. A couple of years ago I made an iroko patio table, glued all the slats with Wudcare PU and several of the slats and some of the ring joints have failed after just 3 winters. I'm faced with having to re-make it.

PU must give off a gas, as it's gas that makes foam. I don't know what the gas is, however, and presumably it is not regarded as dangerous.

I'm currently using Titebond 3 for external and so far so good. But TBH I'm skeptiacl of many manufacturers' claims for their glue, it's all based on best-case scenario, and reality is often different, it seems to me.

CHeers
Steve

 

[Gary M]

Had differing results with PU glue.
On newly planed surfaces, hardwoods for furniture, when i used it , it failed and didnt seem to take very well. :shock:
On rough timber, (mostly tanalised) for gates ect, its second to none. rock solid and cures very quickly (as has been stated already).
Cheers,
Gary.

 

[Harbo]

The Woodworker article states that the gas produced by PU "is an irritant that's harmful to inhale".

There's a table which shows that glues behave quite differently with different types of wood - here's a few from it:
PU does come out well in the strength tests - Gorilla 70% Softwood, 80% Hardwood.
Resin W 100% softwood, 50% hardwood
Titebond 3 70% for softwood and hardwood and 100% tanalised
Aerolite 306 95% softwood, 100% hardwood
Polymite 50% softwood, 90% hardwood

Rod

 

[BradNaylor]

I find PU glue a bit of a pain in the @rse.

It makes your fingers go black - removable only with a pumice stone.

Cleaning up glue squeeze and excess is a nightmare, particularly on mouldings etc. With PVA a wipe with a damp cloth does the trick.

On intricate work the foaming action tends to push the workpieces apart.

But, it's strong and it cures quickly.

So I only use PU for edge jointing boards together and for applying lippings to veneered MDF. For every thing else I find PVA far superior.

I am just making interior furniture however. For outside use I am sure PU has a bigger role to play.

Cheers
Dan

 

[chippy minter]

Thanks for the replies guys, thats given me something to mull over. I might try some polyurathene for jointing some boards up.

I do need a D4 spec as I'm making Beehives and obviously they stand out all weathers, and temperatures.

Just one otherthing, why do'es Cascamite, or whatever its called nowerdays have such a short shelf life?

 

[BradNaylor]

Just one otherthing, why do'es Cascamite, or whatever its called nowerdays have such a short shelf life?

It normally comes as a powder, which you then mix with water.

The short shelf life is when you have mixed it. As a powder, so long as it is kept in a sealed container, it lasts for ages.

Cheers
Dan

 

[Woody Alan]

why do'es Cascamite, or whatever its called nowerdays have such a short shelf life?

Possibly because it's a protein based glue, casein which is a product of milk I think, it's certainly in cheese. So it probably starts to degrade immediately it's made, it's just that there is a point beyond which it doesn't work well. It probably reacts with air even the small amount in the tin, like PU does.

Alan

 

[johnnyb]

still no comment on liquid hide. i for one intended to give it a good tryout after this article......but havent got round to buying any yet. for interior work on oak or open grain it has plenty of strength but it is easy to clean up. and easy to take apart. versatile. very well proven. imho titebond 111 is very thin and annoyingly slow to set. this of course could well be a plus point as well. has anybody got experience with liquid hide is it as easy to get rub joints as with hot hide?how is the setting time.

 

[woodman47]

For cleaning off wet PU thats oozed from a joint, alcohol-based Builders Wipes are v.good, they're available everywhere these days. We use latex gloves for glue ups if theres going to be a lot off manipulation, 'cos black hands gets boring very quickly.

 

[Digit]

When I returned to woodwork after a lay off of many years I was put off of animal type glues 'cos the cost of a decent heated glue pot. Then I picked up a baby's bottle warmer at a car boot for coppers. Result!