Superglue and epoxy resin not working. What next?

[Charlie]

I managed to drop one of my wife's trophies and broke one of the figure's legs. I tried superglueing and that didn't work, so I tried one of those two part epoxy resins (with a double plunger type thing).

I am able to clamp it up really neatly but after 12 hours the joint just comes apart with the glue still wet. What am I doing that is so fundamentally wrong. I thought this was an easy job. I need to fix it in a hurry as she doesn't know yet that I've broken it. I'd like to get it fixed really neatly before I 'fess up.

Cheers

[The Natural Philosopher]

China?

Firs remove all the epoxy with a solvent - acetone is good.

Now mix up more. This time mix it THOROUGHLY. 99% of all epoxy failures to cure are down to inadequate mixing, the other 1% are not waiting long enough.

Stick it back together and remove all excess with acetone/cellulose thinners/nail varnish remover,.

Splint it so it wont come apart,

STOVE it in a WARM oven at < 100C. This speeds up the set time and improves strength, heat resistance and water uptake of the final bond.

Put it back and pretend you didn't notice.

[Maria]

Sounds like you mixed the epoxy with insufficient hardener. I've even used it to mend a leaking car radiator, and never found it to fail. The double plunger thing is bloody awful - I've never found that to work that well because it seems to dispense the incorrect amount due to uneven pressure on the plunger. Can you try a traditional type that comes in two seperate tubes?

[The Natural Philosopher]

epoxy is designed to work at an exact 50/50 mix. (domestic formulations) it is NOT a 'hardener' Is a two pack mix where the reaction is NOT catalysed by one, it is *performed* by BOTH.

[Maria]

Oh ok. I must be getting confused by the epoxy things I have used which do have a hardener. In any case, I have found it difficult to get the same amount to come out of the double tube thing, maybe because my fingers are arthritic. Never had the problem using separate tubes.

[The Natural Philosopher]

polyesters have a 'hardener - a catalyst which sets them off.

The tube may be called 'hardener' in an epoxy, but that's just a silly away of talking , not the actual reality of how they work.

Its bit like saying that in concrete, you have sand, rocks, cement and water, which a 'hardener'

[Andy Burns]

Who can blame people when even Araldite tubes are marked as 'resin' and 'hardener'?

[Nick Odell]

Don't be too hard on people for thinking that: even the brand leader comes in tubes marked 'resin' and 'hardener.'

[The Natural Philosopher]

well its misleading packaging. They should have said 'part A' and 'part B'

Wiki makes the point using plenty of inverted commas

anyway, the key thing is as near equal quantities and very very good mixing..as you can get, and heat is definitely a plus to accelerate setting, promote better mixing and form a stronger joint.

[Gazz]

Super glue (cyanoacrylate) needs water to make it set, usually the moisture in the air is enough, but you can make it go off sooner by spraying the joint with a little water,

you can buy cyanoacrylate kicker sprays, which is basically water and a few other chemicles, makes the glue go off isntiantly, with lots of heat and a little smoke, but also causes the glue to bubble up out of the joint in a white ooze,

But maybe try wetting the break before applying the superglue, but be quick, as it will then set in seconds... or it should anyway.

[Martin Brown]

Those double plunger things are a disaster. The resin and hardener have completely different viscosities and you almost never get the right amounts out. It is a neat marketing trick that is worse than useless.

The other possibility is that you failed to mix it properly. At any reasonable ratio you should get a weaker inferior set that takes longer and has much less strength - maybe even tacky or rubbery but certainly not still wet after 12 hours unless it is kept very cold.

The other thing you might want to do if it is china is find some of the epoxy with a white pigment in so that the mend is nearly invisible. Otherwise you will have a hairline black crack no matter how hard you squeeze it together. Two tubes is better just don't mix up the lids.

Regards, Martin Brown

[Owain]

Pack the whole lot away safely while you repaint the shelf they were on. Or repaint the whole room if necessary.

That will give you breathing space.

What is it / what's it made of? Can you buy another one?

Owain

[Brian Gaff]

And knowing that helps how? grin. I agree the plunger stuff is bloody useless. You may wast a lot doing it the old fashioned way but its going to be a better job. Brian