epoxy question

C

'cacci

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Jul 24, 2008
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I have an elementary epoxy question. Is 5 minute epoxy inherantly weaker than , say, 60 minute epoxy? Thanks for your help.

'cacci
 
From the epoxy wars I would have to say yes. The best was Acraglass from Brownells. But it is a real slow cure, like 12+ hours. I glue up then let sit overnight.
 
Go for a commercial epoxy rather than the low end consumer stuff, right there is a huge difference. After that it's really just picking the right one for your materials and working style. In the generic, walmart type epoxies, 5 minute stuff is much less secure than 30 minute, but you're still comparing the equivalent of the compact economy cars of the adhesive world.
 
One of the best reasons I can think of for using a slow setting epoxy is so I don't have to rush to get the handle together and clamped. I can depend upon making mistakes whenever I try to rush things along.

- Paul Meske
 
Actually, i would say that the BEST is going to be marine epoxy like West System, but that assumes that you also use the appropriate filler material for your chosen application. I am not sure if the Great Blade Forums epoxy test used west with the colloidal silica or micro-balloon filler. I may be wrong. John White, who was a custom boat builder in a previous life, told me that the colloidal silica is a proper filler for most of the things that we use epoxy for.
 
Generally the faster it cures, the higher the temperature reached during the chemical reaction. This can be an issue for delicate and/or unstable materials (ivory, etc), and is another reason to skip the 5 minute variety.
 
The more accelerators in the epoxy, the less resin, hence the weaker the bond.

Using a structural epoxy resin is the way to go.

System Three T-88 slow cure (24 Hr) is my recommendation. West system, and accraglass are also excellent choices. If it cures faster than 1 hour, it is too fast. 24 hour cure has a work life of about four hours, which allows for easy clean up and adjustments as it slowly hardens.
 
Hi cacci

I always use slow curing epoxy but I also heat the items that i want to glue. I use an ordinary old baking oven.
Epoxy cures a lot faster when heatet ...and it also get a lot stronger ( almost twice as strong when cured at 75 degrees celsius.)

I fell that I save time this way and get a stronger bond - but beware ...not all materials can be subjektet to that much heat ( horn - bone i.e.)

Lars Jacobsen
 
A few epoxies I've seen actually have the "hold strength" listed on the package.

How accurate these are I do not know, but the difference between 5 min and 60 min epoxy is negligible to me.

At any rate, I don't think epoxy should ever be exclusively relied on to hold scales to a blade tang, and that being said, I'm not sure that a 60 minute or 24 hour epoxy should ever be the difference of whether your scales fall off, say, over using a 5 minute epoxy.

One may very well be stronger, but they should all be "strong enough". For me, Epoxy is more of a moisture barrier than anything anyhow.
 
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