Hand Tools Archive

Subject:
Re: epoxy ***Links***
Response To:
epoxy ()

John Aniano in central NJ
Hi Jack,

I use three different types of epoxies. The classic "5-Minute" type, G-2 and G-Flex.

For doing the ferrules as you described, the 5 minute stuff is fine. Mix equal amounts by volume and I mix it on a "PostIt note" sheet using a clean wooden stirring stick. Just don't wait too long. Mix it fast, and get it where it needs to be quickly, especially if it's warm in the shop. I like the System Three 5 Minute product, but that's just my preference.

https://www.systemthree.com/products/quick-cure-5-minute-epoxy

For the strongest bonds, and on oily woods, I tend to use System Three G-2 epoxy. I mix it by weight, which I measure in grams with a small 650gram digital scale. Again, unless I need a lot, I measure and mix on a PostIt note pad sheet. For G-2 measure by weight, it's 1:0.44 ratio A: B. So, for example, for 3 grams of resin, you add 0.44 x 3 of hardener, or in this case, 1.3 grams. With G-2 you have maybe 1-1/2 hour maximum working time in normal shop temperatures.

https://www.systemthree.com/products/g-2-epoxy-glue

For some tough jobs where I want a bit of flexibility, I use West Systems G/Flex epoxy. Again, I measure by weight, but G/Flex is a 1:0.83 ratio. So, for 3 grams of resin, you measure 0.83 x 3 or ~2.5grams hardener. G/Flex sets up faster and is a darker tan color than G-2 epoxy's light clear/gray. Same PostIt note mixing regimen. Maybe 40 minutes working time with this epoxy in normal shop temperatures.

https://www.westsystem.com/specialty-epoxies/gflex-650-toughened-epoxy/

In all cases with epoxy, don't think "if I put additional hardener in, it will be a stronger bond" - WRONG! Extra hardener fails to fully combine with the resin and winds up acting like a plasticizer. Maybe someone more versed with chemistry can chime in, but I was instructed by the tech folks at both System Three and West Systems not to add extra hardener as it weakens the bond and makes the cured product less rigid. Best to measure by weight and you get reproducible results.

John

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