Glue

[BradC]

After 40 years of Volvo ownership (degrading plastics mainly) I'm a bit of an "adhesive buff".

For most stuff my go-to's are the old 24hr Araldite or JB-Weld. Both great epoxies. I've found that superglues (cyanoacrylates) can be good under the right circumstances, but long term (5+ years) I've had "mixed" results.

Recently I've been experimenting with UV Cure Acrylics, and they have their place. But I really got on well with Devcon Plastic Welder. That is a relatively new (compared to epoxies anyway) MMA (methyl methacrylate adhesive). Fast cure (too fast for my liking, but anyway) and bonds almost anything to anything else.

Plastics in cars are a curse, and for years I used Araldite. Rough up the substrate and the patch and stick them together. A purely mechanical bond that works across dissimilar plastics. For the same plastics, usually something like dichloromethane or chloroform makes a good bond, but finding exactly the right plastic to use as a patch was always a bugger.

Then I discovered Devcon. Mechanically this stuff is a cross between an epoxy and a solvent cement, and the advantage of that is it creates a mostly chemical bond with most plastics. So ABS to PVC is no issue. Recently I had occasion to repair my pool skimmer box. I wanted something stronger than Devcon, but with a longer cure time. That led me to Araldite 2022-1, so I ordered some only to find they stopped packaging it in the 50ml carts years ago and I got either expired or counterfeit.

I looked around and spoke to a pile of local suppliers and had SFA luck until I came across Acrylictech. I'm not going to post a URL, but you know when you find a supplier who is still small enough to want to help? I've bought a couple of tubes of Acri-bond 210. Stronger than Devcon and about 4 times the pot life. Perfect. I already have the applicator gun from the Araldite. With the skimmer I used the static mixer nozzie, which was great, but for the odd plastic piece I just squeeze a bit out onto an old CD and mix it up the normal way.

The problem is shelf life and temperature sensitivity. Araldite will last for years in a hot car. This stuff lasts 2 years in the fridge and it gets worse from there.

On the other hand, surface prep is optional. I glued a bit of manky PVC to a greased razor blade with not even a wipe-over and the PVC broke before the bond.

Anyway, I think where I was heading is if you have valuable plastics to glue and haven't discovered MMA adhesives, look around. They also do great bonds with non-plastics, so probably better than traditional epoxy as an all-rounder. Just problematic with shelf life and availability. They also don't smell great.

[Tins]

Timely thread. I've been going through my ( mostly set solid ) adhesive collection,, looking for something to help me with this connector. I have no idea how it stayed in place. In my quest to get my D2 going I observed that it was in not good shape. High underbonnet temps, I guess. I want to glue a piece across the lugs. Temporary I guess, nut it might be doable.

195211195212

Both latches are broken, and I believe the only way to get a new plug is to pay around $1K for a harness....... Or cut one from a wreck, if I can find one that hasn't been gutted.

D1 looks even better....

EDIT: It's connector C0171, from the injector harness to the loom that goes to the red plug. Car ain't going without it.

[123rover50]

Any ideas on an epoxy that mixed is still thin enough to run and fill a small cavity with no air bubbles. The few I have tried are all too thick?
Keith

[AK83]

I've given up on gluing plastics.
Got the cheapest plastic welder kit of AliEx, came with crappy nippers, but far better than any glue alone.

The cheapest kits don't have many varied wire sizes, but cheap enough to purchase kits with better selection of those too.

Glue for me is now more of an 'added' filler/strengthener rather than the main adhesive.

For when some plastic part can't be stitched together again, I think fibreglass is better.

[BradC]

Any ideas on an epoxy that mixed is still thin enough to run and fill a small cavity with no air bubbles. The few I have tried are all too thick?
Keith

Heat. I mix up 24 hr araldite in a coke bottle cap and then heat it up under a lamp. Makes it run like water, and it goes off a lot faster too.

[BradC]

I've given up on gluing plastics.
Got the cheapest plastic welder kit of AliEx, came with crappy nippers, but far better than any glue alone.

Yep, but you can't plastic weld dissimilar plastics.

Fibreglass is just a polyurethane epoxy and glass for strength. Polyurethane is alright for certain plastics, but I've used fibreglass woven mat with MMA epoxy also for plastics urethane doesn't bond well with.

[AK83]

Yep, but you can't plastic weld dissimilar plastics......

To be sure, I was referring to the 'staple' type of plastic welding, not filler type welding of plastics.

Hope that makes sense. I find that the metal staples add strength between the parts, and for some intricate shapes, the immediacy of the joint is the primary advantage(ie. not having to wait for cure time).

Hit a roo a few days back, and silly thing cracked the lower portion of the LHS front bumper.
As I was removing the (D2a) headlight one of the locating dowel/pin parts of the headlight must have broken. On the back of the D2a headlight where it gets located into a recess hole in the wing. Has 4 gussets for it's strength.
Very awkward to add the staples into the small spaces between gussets, and it wouldn't sit in place if waiting for glue to cure. So I bent the staples to fit, 4 of them secured the piece perfectly(and if you get it wrong, easy to undo too), then added strategic blobs of epoxy for bonding all the way around .... so to speak
(note the headlight didn't break from the roo strike, it broke from me pulling it out of it's spot).

And the annoying part(4am too) I lost a too many sections of the bumper, was pressed for time as had to get missus to airport so couldn't scrounge too long, just a quick look and remove the hanging fog lamp, and keep driving. .. otherwise if I had the pieces, I'd have stitched it all back together.
So, at the moment, I have a very weird looking bullbar on the D2a.

[BradC]

Knelt on my glasses yesterday and snapped the arm off. Plastic frame with a metal spring hinge inside the arm. I destroyed all of it.

I've done this before (serial offender) and used a combination of epoxy, wound wire reinforcement and glue lined heatshrink to effect dodgy temporary repairs. This time I pulled the Devcon from the fridge and let it warm up, mixed, applied and held in place for 5 minutes while it gelled. This morning the glasses are usable. This is a plastic butt joint with no reinforcement. Araldite would have popped clean off the frame, even with prep, grinding/sanding and post-cure heat.

I used it recently to fix a bracket on our carpet cleaner. Another butt joint that epoxy would have failed to hold together under stress.

Next up, the bracket for the EPB switch in the D3.

[gavinwibrow]

Knelt on my glasses yesterday and snapped the arm off. Plastic frame with a metal spring hinge inside the arm. I destroyed all of it.

I've done this before (serial offender) and used a combination of epoxy, wound wire reinforcement and glue lined heatshrink to effect dodgy temporary repairs. This time I pulled the Devcon from the fridge and let it warm up, mixed, applied and held in place for 5 minutes while it gelled. This morning the glasses are usable. This is a plastic butt joint with no reinforcement. Araldite would have popped clean off the frame, even with prep, grinding/sanding and post-cure heat.

I used it recently to fix a bracket on our carpet cleaner. Another butt joint that epoxy would have failed to hold together under stress.

Next up, the bracket for the EPB switch in the D3.


Wonder how this would go on my snapped mouthguard that I'm supposed to wear each night? Superglue only lasts a couple of days.

[BradC]

Wonder how this would go on my snapped mouthguard that I'm supposed to wear each night? Superglue only lasts a couple of days.

Probably pretty good physically, but I can't vouch for its chemical safety. I don't think I'd use it to repair a drink bottle or water tank just in case it leached something that wasn't good.

[shack]

Wonder how this would go on my snapped mouthguard that I'm supposed to wear each night? Superglue only lasts a couple of days.I'm thinking you should get a new mouthguard.

I would definitely not be using that on it!

[RANDLOVER]

Me too, although years ago I'm sure my dad super glued a crown on until he could get an appointment with his dentist.

[austastar]

Hi,
A dentist or denture service should be able to help.
Whether the cost would exceed the new purchase price, is another story.
Cheers

[Don 130]

Regarding superglue and the body, And old (92) friend knocked her arm while on holiday with the family. The gash that opened almost to the bone, you would reckon was caused by an axe blow. 4" long!! Her son, a doctor was there and while someone put a pressure bandage on, he headed to the nearest hardware for superglue. He said her frail skin wouldn't take suturing and the glue did the trick. I have also had a head wound glued up. So it can't be that bad.
Don.

[austastar]

Hi,
The medical glue has a blue colour, I've seen it used on minor scalp wounds.
Cheers

[RANDLOVER]

I heard superglue was what they use when a boxer gets a cut around his eye during a bout.

[V8Ian]

I've read that super glue was initially invented as a medical glue, for the US military, during the Vietnam war.

[gavinwibrow]

I've read that super glue was initially invented as a medical glue, for the US military, during the Vietnam war.

And I've read that it was developed for space travel ie part of the space race, which encompassed the same time period.

[350RRC]

...............I have also had a head wound glued up. So it can't be that bad.
Don.

Same here, it was in Casualty at a regional Vic hospital.

The doctor said it was basically the same as superglue when asked.

And yes it stung for a minute or so.

DL

[BradC]

And I've read that it was developed for space travel ie part of the space race, which encompassed the same time period.

Whereas apparently it was actually an accidental discovery while trying to develop clear acrylics for aircraft. Discarded as useless then accidentally discovered again a couple of years later. Both just post WW2.

It's an incredibly useful compound. Effectively a moisture cured acrylic that will stick almost anything to anything. Its biological neutrality is what made it useful in combat, but it wasn't developed for it. I'm a card-carrying coward and I've used it twice to avoid having to go and get stitched up.

I don't use it for anything long term however. It's best used for large surface area (near enough to) zero gap bonds. Doesn't seem to have much in the way of shear strength, so butt joints are temporary at best. Incredibly useful when combined with bicarb as a structural filler however. That reaction is incredibly exothermic, so watch out.

[Captain_Rightfoot]

Can we make this thread sticky? [bigsmile]

Sorry seriously useful. I've got some 60 year old dash plastic that needs fixing. I'll look this stuff up.