5 Minute 'Waterproof' Epoxy

[Kazzer]

I've noticed on a couple of forums that people are under the impression that 5 minute epoxies are not waterproof, so aren't used for submarine model making or repairs.

I've been selling epoxies for over 25 years and I've only every encountered this on submarine forums, so I'm puzzled how this snippet of information came about. It seems to be 'cast in stone' these days.

The hardener in these epoxies is a mercaptan, and has a strong, garlic-like odor to it and is easily recognizable. It does not have the same adhesive strength as the slower curing materials, and it is usually a paste-like material, so I can imagine it letting loose on a plastic or very smooth surface, so maybe this is the reason some have had failures?

I've used 5 min epoxies in many underwater situations and never had any problems, so I'd like to hear from anyone who has, just to see what they did.

The base part of the resin system is usually the same material used in the slower curing resins, only the hardener being different, so the material is actually waterproof. Bond strengths are lower, but still strong enough for anything on a submarine model.

[Slats]

ME-
we have a product here called 5 min araldite - its meant to be H20 proof expoxy - but the moment the dry product is saturated it tends to de-laminate / de bond. It feels all flexible to touch rather than a hard solid.

Have watched a U boat sub surface all by itself.
Operator was perplexed as why the boat had surfaced - lots of TX input and nothing.
Waded into lake to bring her in relieved that what ever the problem the sub was on the surface - WRONG!
Poor chap discovered what he was seeing was just the deck. It had delaminated /de bonded from the boat proper. All that TX input was actually driving the boat at a fair clip into harms way - the boat took 3 weeks to find at my local dam using professional divers.

Oils ain't oils and not all products I guess are the same.
It would be nice to know which ones are ok and which have these quirks to be avoided.

J

[Subculture]

I don't use epoxies at all for subs since discovering modified acrylic adhesives. They really are the dog's doo-daas.

Deluxe Fusion, Devcon Plastic Welder, Stabilit Express etc.

They do pong a bit, not as bad as polyester resin, but still enough to rattle the missus if you're working in the house. They also sand really well and accept fillers.

Andy

[redboat219]

I bored out the sail window on the Kilo and filled them in with extra strength slow set epoxy from ACE Hardware to represent the glazing. The epoxy dried to a translucent amber. Curious thing is that the epoxy didn't harden as I expected it would. It has a somewhat rubbery feel. Well the notes at the back of the pack claims it's resistant to solvents, moisture and impact. I remember seeing a marine version which I assume can be used on boats. Unfortunately the store no longer stocks it.

[Subculture]

As the Germans say- the devil is in the detail.

When they say something is water resistant, that means it will withstand the odd shower from a watering can. You need something that is waterproof, and that's what it should say on the tin.

I too have found epoxy adhesives tend to remain 'chewy', I think that is part of the idea to help retain flexibility.

[redboat219]

I think the reason why my epoxy has a rubbery consistency. I may have made an error in the mix ratio of the resin/hardener. Since the components come from individual tubes I may have squeezed out more hardener. I remember reading that adding more hardener to the resin doesn't mean it'll be hard.

I initially attached my Kilo's resin stern planes using the slow set epoxy. I clamped the resin and styrene together using rubber bands to get a close fit and squeeze out extra epoxy. Here I noticed that the epoxy set hard and the resin stern piece was firmly attached to the styrene.

Later I found out how good or bad the bond was when I was fitting the movable planes and the square brass tubing. It was a tight fit and I was pushing the brass piece in when I heard a loud crack. The front half of resin port stabilizer snapped off it's attachment point on the styrene hull.


I cleaned the cured epoxy off the attachment point and used regular CA and baking soda to rebond the stab to the stern.
So 1 stab is attached with epoxy, the other with CA. We'll see which one holds when I finally get the kilo wet..

[Slats]

I just won't use it, especially when there are so many good alternatives.

To add to my recent post on this - I have also seen a 4 piece Revell hull of the Flower Class part company with 5 minute araldite letting go. Ok the guy should have welded the plastic with a proper stryene hobby glue.

As far as mixing goes the 50:50 ratio of 5 minute araldite is not going to alter the bond much if you make a SLIGHT differential error. Yes you should aim to take all care to nail the ratio precisely but the manufacturers fully anticipate the end user is likely not to nail it every time.

I now use Bostik Titan Bond Plus for all wet exposes and submerged applications - hell this even sets underwater! Working time is 15-30 minutes, initially cures in 3-4 hours, sets hard in 24 hours, but keeps on curing for up to 7 days.

http://bostik.co.nz/directoryproduct.aspx?dc=Titan%20Bond%20Plus%20-%20Underwater%20Glue

here is the Tech data sheet:

http://bostik.blackweb.co.nz/doc/TITAN%20BOND.pdf

If I need a quick 5 minute fix for a minor part- I use Green ZAP CA.

If I need to position a part quickly that needs a tough expoxy bond, I will cut a drain channel into the part to take the Titan Bond glue, tack adhere the outside of the part in position with a few drops of Green ZAP CA, mix the Titan bond, and then pour it into the drain channel, utilising gravity.
Alternatively
For say installing the a dive plane horizontal assembly (like in your photo), I will drill and insert brass pieces into the assembly and dove tail these into corresponding holes drilled in the hull. I will then apply Titan bond to the hull and assembly and push fit these together. I then clean up any overrun with a rag, support the hull and assembly at right angles and leave to set for 24 hours before doing the other side. Slow - but good processes occasionally take time.


J

[Kazzer]

ME-
we have a product here called 5 min araldite - its meant to be H20 proof epoxy - but the moment the dry product is saturated it tends to de-laminate / de bond. It feels all flexible to touch rather than a hard solid.

Poor chap discovered what he was seeing was just the deck. It had delaminated /de bonded from the boat proper.

J

Araldite is a Ciba Geigy product, nothing shabby about it at all. What this looks like to me is a wrong choice of product, as I can't imagine trying to glue a deck to a boat with a fast setting epoxy. How would you get that all along the hull before it started setting up? I suspect the resin had partially cured before he'd finished.
It would also be interesting to know what the boat was made of, and what surface prep was carried out. Epoxies don't just give up, they fail because of - bad surface prep, bad mix ratio, bad mixing, inadequate temperature.

[Slats]

Hi Mike,
I still use Araldite but not the 5 minute variety. With what you identified here
"surface prep, mix, temp, and the speed it which it cures", makes a lot of sense.

I think with those potential errors possible -as you state it comes down to choice of application or perhaps poor choice for some jobs. That is I think the 5 minute stuff would be best used for minor small jobs - rather than lasting large ones such as the Flower hull and the U boat missing its deck.

All good info.

Thanks
John

[Subculture]

That Titan Bond plus looks a superb adhesive, unfortunately it doesn't seem to be available outside of Australia.

There are a far more limited range of adhesives to modellers here in the UK for some reason, generally if you want the really GOOD stuff you have to look at industrial grade products. Unfortunately they tend to come in industrial quantities with corresponding price tags- frustrating.

[Kazzer]

Hi Mike,
I still use Araldite but not the 5 minute variety. With what you identified here
"surface prep, mix, temp, and the speed it which it cures", makes a lot of sense.

I think with those potential errors possible -as you state it comes down to choice of application or perhaps poor choice for some jobs. That is I think the 5 minute stuff would be best used for minor small jobs - rather than lasting large ones such as the Flower hull and the U boat missing its deck.

All good info.

Thanks
John

Araldite is, of course, a brand name which covers a large variety of resin systems, so just using 'Araldite' isn't going to determine what you have.

John hit it on the head, poor choice for bonding a hull together, especially when you can make a true weld using the methylene chloride solvents to fix a deck on with. So why use a resin that needs a roughened surface and large surface area to make a good mechanical bond? And worse still, what mating surfaces are being bonded with this material? I imagine these decks etc. were simply being glued along the edge of the deck, so a minimal surface area was exposed to the adhesive. Any slight flexing of this large part would put the adhesive under great strain on the joint, whether it were under water - or not.

I think we can safely say now, these 5 minute epoxies (pungent smelling hardener that skins over with excessive exposure to air) are waterproof as I have always been let to believe by the manufacturers, their failure is simply a matter of the operator making a bad choice of materials.

My article on adhesives can be downloaded here.

[Kazzer]

I think the reason why my epoxy has a rubbery consistency. I may have made an error in the mix ratio of the resin/hardener.

If your ratio is off, you could either make it rubbery or very brittle. Rubbery means insufficient hardener, brittle means too much. Mixing very small batches increases the chance of having your ratio wrong. Better to mix up too much and get the ratio right.

I cleaned the cured epoxy off the attachment point and used regular CA and baking soda to re-bond the stab to the stern.
So one stabilizer is attached with epoxy, the other with CA. We'll see which one holds when I finally get the kilo wet..

I would have made a metal pin and stuck it into both parts of this damaged piece, like a reinforcing bar. This would have greatly enhanced the success of the repair. To line up the re-bar, drill a hole in one part the same size as the bar, and then drill an over-sized hole in the other part. Make sure you can line up the part correctly, then fill the over-sized hole with resin and coat the entire joint with epoxy (5 minute stuff is ok) to complete the repair.

Getting the Kilo wet will have no effect on an epoxy repair. It's not the getting wet that caused the problem, its bad repair technique. I hope this helps everyone understand this a little better.

[Albion]

I used to have Araldite as a customer in the UK. I remember that a number of the engineers had made coffee mugs cast out of Araldite. No coatings just product. It held up pretty well to hot coffee

[Tugfan]

So, will CA work on parts getting wet or not? I use a 30 min. epoxy and never have had a problem. You could hit it with a hammer afterward. Micro balloons also work well mixed with epoxy for a great hard setup.

[JBarche]

Hi,
As far as I know (I work with epoxies in paints -but the privciples should be the same), the main problem with these 5 minute epoxies is that they tend to have an accelerator added to the hardener.
The most common one (I won't tell you the name - it would fill half the line) does two things - it makes the epoxy brittle and it is quite well soluble in water. So if you immerse it sime material will leach out and further weaken an already brittle bond. The good thing with that stuff is that if you have used slightly too much epoxy it helps to post-cure the resin in an oven (as long as your wife dosn't find out). judt stich it in at 80 - 100degC for an hour or so and the material should gain some strength.