Are all epoxy glues equal?

[Scribbly Gum]

The only epoxy glue I have ever used is Araldite.
I've never even thought that there might be alternative epoxies out there.
Have any comparative tests been done on different brands that would recommend one over another?
I await the wisdom of the forum.
Regards
SG

[Cruzi]

Rule of thumb I was told, was the slower the curing, the stronger the bond.

Experience has taught me that 5 min Arildite is rubbish, but the Super Strength is fantastic, that takes about 3 days to cure though.

[BobL]

Rule of thumb I was told, was the slower the curing, the stronger the bond.

Experience has taught me that 5 min Arildite is rubbish, but the Super Strength is fantastic, that takes about 3 days to cure though.

Slower curing works up to a point. It means the reaction has time to proceed to completion and make the molecular cross linkages necessary to form the bonds. If the reaction is too slow (as per thumbsucker's post - when the temperature is below the setting temp for some epoxies the reaction never completes and few bonds form so it never hardens)

. . . . and the fast drying is the best because it is the thermal reaction that hardens it - so the hotter it and the environment is the faster it cures and the harder it is.

Ultimate strength and temperature are not necessarily related. Temperature drives the reaction rate of crosslinks so theoretically it gets hard faster. But fast reactions don't always produced optimal bonding so maximum strength is not always achieved in rapid time. This is why the 5 min stuff is not that good.

Different hardeners are used to control the setting times and for specific working conditions. Slow hardeners allow the user to work the epoxy for longer especially under warmer conditions which would otherwise harden to early.

Then there are fillers and binders ....... it's a huge topic. Check the web.

[Cruzi]

"Rules of Thumb" are only accurate up to a point I spose.

Should point out that the Super Strength does set in an hour or so, just curing does take some time.

There was mention of the West Systems Epoxy, another woodworker I know swears by it. I just can't justify having that much epoxy around.

[JDarvall]

I've been thinking about buying a couple of big tubs of it for home for a while. Far more economical aproach I'm told.

Where would anyone recommend it being bought though ?

[billbeee]

Hi All,
From what I can gather there are maybe only one or two chemical companies that make the stuff. Then resellers use various hardeners and fillers and repackage for sale. The hardeners are what determines the quality, from specialist to fairly generic cheapies.

As bobl says it's a huge subject and no one product is right for all occasions.

I'd be searching what the timber boatbuilder's use if you are after top quality.

I wouldn't be buying too big a tub apricot, nothing more than what you could use in a year or so.

Cheers
Bill

[JDarvall]

Hi All,

I wouldn't be buying too big a tub apricot, nothing more than what you could use in a year or so.

Cheers
Bill

Ta Bill. Has it got some kind of use by date?

At work the bosses got a big tub about the size of an icecream container with a smaller hardner beside it.

[mcchaddy]

Hi All,

I have used West System for a while now. I have used it for just about everything around the house. Filling stripped screw holes in casement windows to glueing stainless steel brackets in our pool area. Fabulous stuff. I also use it on joints where i need strong bonding. I have never had it fail yet. I'm in the process of building a small sailing boat and it is ideal for laminating pieces together, filleting joints........ the list goes.

It isn't cheap but the expense is worth it as far as i'm concerned. I found the cheapest place in brisbane was Glasscraft marine. They have stores in other states i think and you can also order on the web. I bought a 4ltr resion and 800ml hardner plus a bag of micro fibres and some sanding compound for about $220 from memory. I made up a little storage area for it that holds mixing sticks, plastic mixing cups, rubber gloves etc all within easy reach. When i need to glue something I just pick it up and take to where the job is and its all there ready to go.

A good clean up tip is to use a heat gun and a scrapper. The excess resin just peels off once it is warmed up.

Cheers

Michael.

[Wild Dingo]

okay not to bring any bias in here but aside from West System which everyone knows is the ducks knuts

there is also Boatcote sold through various places but on the net boatcraft pacific flog it... it works as well as Wests and has the benefit of being slightly cheeper in cost

[Tony Hunt]

I've used Megapoxy 69, made and sold by Vivacity Engineering at 3 Sefton Rd Thornleigh (NW Sydney) and it's good stuff - cheap easy to use (1:1) etc. They sell a tub that is about 1 kg each of the hardener and resin, I used it over a two year period and it was fine.

http://www.megapoxy.com/homepage.htm

[mcarthur]

Another issue of course is toxicity. I was told that the lower the percentage of hardener, then more toxic it is. Hence West at 5:1 was more toxic than System 3 (showing my age here) or Botecote at 2:1. Of course both are going to kill you if you persist in not using gloves and sniffing the d@mn stuff, so a little common sense and serious reading of the safety literature that comes with them is needed. Another one for toxicity is the old Everdure, which was (is?) used as a nice thin barrier coat often inside a boat. Now getting it inside the boat meant sticking your head & body into crevasses and, almost without fail, getting lots of nose-fuls of disgustingly nasty carcinogenic compounds.

Personally, I quite like the 2:1 Botecote...

Rob

[AlexS]

I use Techniglue regularly and it's excellent. It has the consistency of a thick cream and gives about 30 mins working time on a normal day. I understand that it's made by the same people who do West system. Haven't used West system, but I understand it has a liquid consistency unless a filler is added. Tony, I was going to try Megapoxy as they're just around the corner from me. What's the consistency and working time? Another one I want to try is L39 slow adhesive from Adhesive Engineering in Hornsby [email protected] .

[Toolin Around]

Epoxy on its own is very fragile. If you don't believe me pour some in a container and let it set off. Pop it out of the container when it's hard and give it a good whack - it'll shatter easier than glass. Put some form of fiber in it and you can't break it when beating it with a hammer. No matter what brand you buy you should always be putting a filler in it if you want it to be strong.

[Tony Hunt]

Alex

The consistency is like peanut butter when first mixed, gets a little runnier as it reacts. In warm weather it starts to kick within about 20-20 minutes, I've never found the working time to be a problem (except when trying to correct mistakes!). In my opinion it's good stuff.

[BobL]

Another issue of course is toxicity.

Here's the run down where I partially poisoned myself with two-pack poly hardener!