Epoxies.

[jason0012]

For quite some time I muddled about gluing scales on with the epoxie from Home Depot that comes in the syringe. It can be a bit rubbery and has a nasty habit of just letting go eventually (at least pins hold…) A few years ago I bought some Accra glass from brownells, which is way better but a tad pricey and probably overkill. It occurs to me, there are probably other such products out there. So what kinds of epoxies are everyone using?

[Frosty]

Welcome aboard Jason, glad to have you.

I'm going to PM a link to another forum not allowed here that should answer your questions.

Frosty The Lucky. 

[M.J.Lampert]

JB weld has worked well here, and it's always good to have some for other fix it jobs.

[George N. M.]

I've generally found that the longer the cure time the stronger the bond.  A 12 hour curing epoxy will give a stronger bond than a 5 minute one but there are times when a 5 minute cure is perfectly adequate.

"By hammer and hand all arts do stand."

[Steve Sells]

except in testing, many 5 min epoxy's fail after only a few years

[Frosty]

Polymerizing resins, epoxy or polyesters to name the two most common harden when the long chain molecules intertwine and bond chemically at various sites. Epoxies tend to be stronger because the molecules are twistier so to speak so when they polymerize they interlock at more points. 

Anyway, the faster they set the less time the molecules have to intertwine and so the bonds aren't as strong. The catalyst isn't actually necessary polymerizing resins will set in time regardless, what the catalyst does is cause a reaction that generates heat on a molecular level. 

The often flaming results of adding too much catalyst isn't so much caused by the resin setting but by the catalyst itself. 

You can set and cure resins by heating them but unless they're designed for heat cure it's tricky to get right.

Anyway, the slower the set and cure the stronger. 

Old surfer and rubber plant employee who mixed a LOT of various resins privately and professionally.

Frosty The Lucky.

[templehound]

On 10/29/2022 at 2:46 AM, Steve Sells said:

except in testing, many 5 min epoxy's fail after only a few years

Steve, you are absolutely right!....seems that many well known knife makers ignore that fact.

On 10/29/2022 at 7:33 AM, Frosty said:

Polymerizing resins, epoxy or polyesters to name the two most common harden when the long chain molecules intertwine and bond chemically at various sites. Epoxies tend to be stronger because the molecules are twistier so to speak so when they polymerize they interlock at more points. 

Anyway, the faster they set the less time the molecules have to intertwine and so the bonds aren't as strong. The catalyst isn't actually necessary polymerizing resins will set in time regardless, what the catalyst does is cause a reaction that generates heat on a molecular level. 

The often flaming results of adding too much catalyst isn't so much caused by the resin setting but by the catalyst itself. 

You can set and cure resins by heating them but unless they're designed for heat cure it's tricky to get right.

Anyway, the slower the set and cure the stronger. 

Old surfer and rubber plant employee who mixed a LOT of various resins privately and professionally.

Frosty The Lucky.

My man!....I could not say it better!

[Frosty]

Thank you, I took a 2 day class 50 years ago at the rubber plant where I worked. 

And just so nobody assumes JB Weld is a poor epoxy it isn't. The 5 minute epoxy has all the failings of any fast cure epoxy. The brand on the other hand has been around for I don't know how long 55+ years I know of personally. To even stay on the market let alone be as successful as it is they have full time labs developing better glue so don't turn your nose up because it's JB Weld on the package. Just use the slower setting formula if you need strength. The slower the stronger.

Frosty The Lucky.

[wicon]

"UHU plus endfest 300" was always my choice and it worked well von me. But some years ago they changed the recipe. Now it ist not half as good as it was. But in their Professional Shop you can still buy the old recipe. Honi soit qui mal y pense.

(I don't know, wether it is available in the US. I think it's more a german brand.)

Willy

 

 

[JHCC]

7 hours ago, wicon said:

Honi soit qui mal y pense.

Caveat emptor?

[Latticino]

G-Flex is the go-to epoxy for most of the knife makers I know.

[wicon]

1 hour ago, Latticino said:

G-Flex is the go-to epoxy for most of the knife makers I know.

Looks good, will try. Thank you.

Willy

[Buzzkill]

There was a thread on one of the knife making forums I read a while ago that addressed the epoxy issue.  If I can find it I'll either post the link or the words to use to find it.

Anyway, the author used quite a few different adhesives for testing and used both synthetic and natural materials for handles.

Ultimately some performed better with certain materials than others so there was not a clear winner.  However, a couple things became very clear: 1) Proper preparation of the mating surfaces made a big difference in the performance of the adhesive, and 2) Using the correct amounts of the components for 2 part epoxies (and mixing them thoroughly) had a big impact on their performance.

There were some like West System (who makes G-Flex) and Acraglas that seemed like solid performers in nearly all tests, but there are different versions of epoxies within those name brands as well. Gorilla Glue had a surprisingly good showing in some tests as well.

I couldn't find the thread on a quick search, but if I find it later I will put the information here.

[Buzzkill]

Ok, I found it.  It was on The Knife Network site and the thread is called Glue Wars.  There is also a Glue Wars 2 on Blade Forums.

[Frosty]

I have the link Buzz I PMed it to the OP to avoid linking to another forum. Well, I THINK we're taking about the same forum and thread.  It's a really involved series of tests by quite a few knife makers with some surprising results. 

It's called "Testing For The Ultimate Adhesive" on The Knife Network Forum . com. It's a few years old but definitely a good read. 

Ah yes, The Glue Wars! we're talking about the same one.

I'll post the link to the forum if it's okay with Admin.

Frosty The Lucky.

[ThomasPowers]

Wicon; are you gluing your Garters on?

[wicon]

No, I'm not a member of that order. (And Epoxy might not be the best choice for that application.)

Wlly

[Frosty]

Better than staples.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

I have used Acraglas from Brownells for decades on both knives and firearms and to my knowledge never had a failure of the epoxy to date. It has been on backorder for a while now though and they have a newer Acraglas gel that is supposed to be improved but I've not tried it yet.

[Jason Fry]

Late reply to this one, but I'm a fan of G flex.  I used Blade Bond for a few years also with no regrets.  

One thing I've noticed is that you can speed the cure up a bit with warmth.  I set the glued up knife in front of my shop heater in the winter, or out in the sun in the summer.  Cuts the time down to 2-3 hours and lets me get back to working on the knife faster. 

[Frosty]

Yes, you can cure epoxy by heating it without the catalyst. Just remember, the slower the cure the stronger the bond. Don't let being in a rush screw things up for you.

Frosty The Lucky.