Epoxy temperature

C

cjensema

Joined
Dec 29, 1998
Messages
288
I work on knives in an unheated (except for a small space heater next to the workbench) garage in Maryland. Temperature in there varies from a high of 90 degrees in summer to a low of 40 degrees in winter. In winter I take knives into the 70 degree house to dry after I mix epoxy and attach the handles. In summer I just leave the knives in the garage.

Will these variations in temperature during gluing seriously affect the strength of the epoxy bond?

Incidentally, I use 24-hour epoxy and usually let a knife sit for two or three days to be sure the bond is cured.

Carl
 
To the best of my knowledge (having made just a few knives), you're doing right by doing that. Down here in Texas, we have a temp variance of ~30-~110 degrees. At the extremes for either end, I bring it inside. My best suggestion, though, would be to check either on the epoxy itself or with the manufacturer to find a working and curing range for their products.


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One little nuclear holocaust can REALLY hose your bowling average...
 
As I recall you can get a 25% strength improvement if you cure your epoxy at around 150-degrees F. You don't want to go too hot or different thermal expansion coefficients of the handle and the tang will cause built in stresses when the handle cools back down. Also you need to not over heat your handle material.
 
warming up the handles a bit helps....i just put them in the sun here...but you definitely dont want to get them hotter than you can hold in your bare hands.....if you read the directions they usually say 75 degrees.....

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http://www.mayoknives.com


 
I dont make knives but sometimes have to glue irradiation capsules shut with epoxy. Aluminium capsules and caps are glued together with regular araldite. I use a lot glue to ensure that capsule will be waterproof. Normally I prepare capsules too late and have to accelerate hardening reaction by applying some extra heat. I put capsules under table lamp. Temperature under it is about 50 C (upper limit is 60 C I think). I don't have tried strenghts but it hardens considerable faster. If temperature is too high the glue (not to mention possible problems with hardening) is too fluid and does not stay where I apply it. As you apply it between surfaces it is not as big problem.
 
I like to get metal hot enough that I can only hold it for about 5 seconds comfortably. This will cure it faster and harder than room temperature.
 
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