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On 3/10/2018 at 2:35 PM, Jason McEntee said:

I use Devcon Flowmix 2 ton---the 12 hour cure stuff. Have yet to have any issues with it.

I use the DEVCON 2 ton long set epoxy that comes in a box containing a plastic bottle of 4.25 oz of resin, and another holding the same amount of hardener. I have used this since the late 70's. Devcon is clear, thin, and easy to pour into a hidden tang grip. I have never had a come back because of it. I always drilled my full tangs out like Swiss cheese. This makes internal epoxy bridges from grip slab to grip slab. Adheres to buff horn like it grew from it. Same with clean dry bone or wood. I have read that Devcon will not hold up to moisture, but I have a small full tang 4" bladed neck knife with bone slabs attached with 2 1/8" iron pins, not peened, and Devcon, that I made about 12 or so years before a flood happened here in 2008. The knife was lost in the flood under 4' of water for around 4 months. It was later found in some still damp mud. Still tight together, although the steel was a red mess. I still have it but never fully cleaned it up. The slabs are still tight to this day. Original Acraglas is the strongest, but I never liked waiting 3 days for it to fully cure. As I recall, Acraglas is rated as having at least a 50 year life span. I have read negative claims on Devcon, but it has done me very well for many years. This is based only on my experiences. There are many good adhesives available now, and you must make your own choices.

 

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This makes me feel much better, as I use Devcon epoxy strictly out of convenience (I can grab it at the local hardware store).  As long as there has been a mechanical connection to back it up, I've never had an issue with it either.  I've read the same relatively negative reviews as well and have been wondering if I should be switching to something like G-flex.

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  • 3 weeks later...

Speaking as someone who has experience using epoxy to join steel into concrete and hanging a building off of it, I think most of the problems with epoxy failures come form poor mixing practices. Two part epoxies can be very finicky when it comes to getting the ratios of hardener to resin correct. Too much hardener and the epoxy becomes brittle and will crack in heat. Too little hardener and it never sets properly. There are two-part epoxy products that come in double-barrel syringes so you always get the correct mixture, and they have the added bonus of being able to control the flow into a hole easily with little to no mess.

Whatever product you use, make sure you keep a small amount on the workbench to check for set up. Come back to this test puddle after the specified set time to check and make sure it has set properly. If it hasn't take everything apart, clean it up, and redo the process. Epoxy shelf life differs from product to product and changes with environmental conditions. So that huge bottle of West Systems that has been in the garage for the last 5 years may not be any good anymore......

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22 minutes ago, Joshua States said:

Speaking as someone who has experience using epoxy to join steel into concrete and hanging a building off of it, I think most of the problems with epoxy failures come form poor mixing practices.

To add to this, I once did a study on the effect of mixing times on the setting on 5-minute epoxies.  When the instructions say "Mix for 60 seconds" it turns out they really mean that.  Most people I observed mixing epoxy did it for 10-15 seconds, and thought it looked mixed enough.  It turned out that under mixing caused for a much longer cure time.  I can't say that it harmed the overall strength, but it would be a reasonable hypothesis to make.

 

Next time you mix epoxy, count to 60 slowly.  Seems like a very long time when you do it :)

 

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  • 1 month later...

I'm still very new to bladesmithing with a whopping six months under my belt.  But in that time I've tried several epoxies and I've found that J.B. Weld's ClearWeld (5 minute set, 4400 PSI) is amazing.  The key to any epoxy (I've worked fiberglass fabrication) is ratio and mixing time. For knives I always use tongue depressors to mix and apply epoxy to the tang.  I set a timer for one minute to ensure the epoxy is evenly mixed.  I've yet to have a scale come loose.  I also ensure that my pins are a press fit into the tang to make sure they can't move and break the epoxy apart over time.  The other thing to ensure perfect adhesion is to be sure to clean your scales before applying epoxy.  I've watched many local bladesmiths slather on the epoxy without cleaning the dust off of their materials, only to see a scale pop off during testing.

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25 minutes ago, Brian J said:

I've found that J.B. Weld's ClearWeld (5 minute set, 4400 PSI) is amazing.

 

Been using that myself.

 

So far I am quite pleased.

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  • 2 months later...

Yes, it is. 

Just be careful to keep it off the outer surface, unless you want to finish the whole thing with a thin coat.

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