What epoxy are you using?

Rick Marchand said:
The pumps work. West Systems stake their reputation on it. You have to prime the pump before you use it and don't do "half" pumps, thinking you'll nail it. Full pumps(bottomed out) or nothing.
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Rick is correct. There is a proper way to use the pumps. Follow the pump directions and the ratio will be correct.

Here is a quick G/flex history. In 2009 I contacted West System and asked about G/flex. I bought samples and a friend and I tested G/flex bond strength. The friend has a Phd in engineering. We compared Acraglas vs G/flex bond strength on many different materials. After testing we decided to discontinue Acraglas and sell G/flex. The deciding factor was the shock resistance and flexibility of G/flex. The shelf and bond life is the same as Acraglas. In 2010 we introduced G/flex to knifemakers.

Chuck
 
You can get digital scales dead cheap, $10 or $20

Put a cup on , tare it add one , tare it, add the other


There is a trick though, the ratio in volume is not the same as the ratio in weight.
They have it all figured out though, you just need to see the website for the info
 
Rick Marchand said:
...I am not accusing you of not reading the instructions, bud... there may have been other issues as well.
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Ha - everybody knows I can’t read instructions! My better half suggests testicles are directly in my line of sight. Yep.

Actually I have made a living measuring things precisely for a few decades now but I really should have offered this caveat in fairness to West Systems: The pumps I spoke of were NOT from WS but are of similar fixed-volume design and were US made (aka lab-grade units intended for this type of material). They worked fine for 4 or 5 months (maybe twenty uses or so for me) then volumes began to visibly drift in the setup I was using (measure>combine>mix>color>mix> transfer to clean cup>apply). I took both to the lab, cleaned them properly, primed both with fresh components, then measured their output volumes and repeatability. Was surprised the CVs were something over 7% pumping epoxy resin and almost double that with the matching hardener. That’s 0.35 mL slap at 5.0 mL. That variance is easily visible and was not acceptable to me personally when there are better alternatives.

Common sense, quality syringes and/or an accurate balance can help weed out any related problems.

I’m just saying that after all the work you put into making your tools, IMHO trusting those sketchy pieces of plasticware to get this critical measurement right every time is shortsighted at best.

Then comes the whole thing of not shooting ourselves in the proverbial foot while actually using the stuff!
 
As far as using syringes. Very nice,cheap, and variety of sized syringes can be found at feed and tack stores in the horse section.
 
Acraglas and scales here.

I figured the .250 by volume ratio is .263 when done by weight, the hardener is a little more dense than the epoxy. Scales are nice because you can measure it out to the drop and you can also measure your dope.

I went to acraglas because of the shelf life and reliability, but I've also come to value its hardness which allows it buff out bright when used to fill voids. Ever mill carbon fiber? It looks like a Rastafarian when you're done, but a little black acraglas and it's perfect...


...super glue... meh...
 
One of my favorite things about acraglass is it's watery consistency, it flows well into all the nooks and crannies of a hidden tang... how do the West Systems compare?
 
The West Systems G/flex 650 system provides 45 minutes of working time, and doesn't harden until 24 hours . . . longer if the temperature is cool. It flows into cracks well and for a long period of time after mixing. I recently tried to use it to seal the drain port on the bottom of a ceramic vase which was permanently fitted onto a saucer drain plate, and the epoxy wouldn't quit flowing out of the hole in the bottom of the pot until I let it sit for about 4 hours then added wetted cloth fillers into the drain port and a new mix of epoxy. Now it holds water like a charm!
 
The other nice thing about the West System materials is you can call them and talk to a tech support guy any time. They have been making and selling epoxy for so long that they have seen and solved any problem you can think of.
Tim
 
One more vote for G-flex.
It gives plenty of time to cure and was made to put together boats and airplanes. It has flex as in the name.
 
I hope nobody minds, but I hope this post boils down what the count, Rick, Chuck, Nathan and all those who are experienced with these materials even more than myself are saying.

First, choose an epoxy for what you want it to do... Acraglas is great for void filling and absolute adhesion. G-Flex is comparable adhesion with a bit of flex. The 105 system adds chemical flexibility in that the final color/cure/bond can be manipulated easily with a hardener change. The names you hear thrown around here regularly for epoxies are all top of the mark and have passed the QC of some pretty picky customers - knifemakers... Choose accordingly.

Second, ratio matters for all epoxies. Off by just a touch can cause an epoxy to fail to cure, be too brittle, have a greasy final feel, etc. Measure twice, mix once.

And third, just to add, IMO your prep will determine more than any other single factor in your epoxy joints stability. If your prep sucks, even the best epoxies won't work worth a toot.

Asking this question is like asking a group of cops which type donut is the best. They can all be good, but all have their different purpose.

-Eric
 
LucyCustomKnives said:
Asking this question is like asking a group of cops which type donut is the best.

-Eric
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Wow... And here I thought we lived in a day and time where such generalizations and stereotypes were no longer used.

Plus, everyone knows the best donut choice depends upon which coffee you're drinking. :D


Jeremy
 
LucyCustomKnives said:
I hope nobody minds, but I hope this post boils down what the count, Rick, Chuck, Nathan and all those who are experienced with these materials even more than myself are saying.

First, choose an epoxy for what you want it to do... Acraglas is great for void filling and absolute adhesion. G-Flex is comparable adhesion with a bit of flex. The 105 system adds chemical flexibility in that the final color/cure/bond can be manipulated easily with a hardener change. The names you hear thrown around here regularly for epoxies are all top of the mark and have passed the QC of some pretty picky customers - knifemakers... Choose accordingly.

Second, ratio matters for all epoxies. Off by just a touch can cause an epoxy to fail to cure, be too brittle, have a greasy final feel, etc. Measure twice, mix once.

And third, just to add, IMO your prep will determine more than any other single factor in your epoxy joints stability. If your prep sucks, even the best epoxies won't work worth a toot.

Asking this question is like asking a group of cops which type donut is the best. They can all be good, but all have their different purpose.

-Eric
Click to expand...

I think i will end up getting a small sample of each of the three kinds and test them out. although i am disappointed i might have to deal with out the convenance of a pump system but its only a small thing.
 
There are 2 types of acraglas.
1. Gel.
2. liquid.
Both have their own purpose. Most kits I have gotten come with a measure spoons that you can accurately measure "By volume" equal amounts. I have got to the point where I order the family size that does not come with the measuring cup. I just use a disposable Dixie cup. I think you have to be pretty close, but not like .01 grams close.
The kits also usually come with brown, and black die you mix in after you have done the required 4 min. mix of the 2 components to get the desired color you want.
 
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