Epoxy question

F

frugalweaver

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Jul 3, 2005
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112
I glued scales to a blade, after three days the glue is still a little rubbery. The epoxy was about a year old but still very liquid and mixed well, looked OK. I'm pretty sure I got it half and half. Just eyeballed not measured on a scale or anything. It worked great on the last knife I made.

Will it continue to harden? Will it be too weak and fail at a bad time? Should I remove the scales and start over? What is the best way to remove epoxied scales from a blade?
 
After the accident at the 'Big Dig' in Boston recently I'm afraid of epoxy. There , bolts holding heavy ceiling panels where epoxied into the concrete above and the epoxy failed !!....Do a search on the forum for extensive tests done on various adhesives.
 
That seems really unusual for epoxy. I use the great stuff all of the time and that hasn't happened. What sort of scales are you bonding? If you can get the scales off, then they could be cleaned with mineral spirits or something similar. If you can't get the scales off.... I wouldn't know how you could except for just burning them off....
I don't know if you have a really set idea for your knife and don't want to deviate from it, but you could also just try putting in some reinforcements (screws, rivets, fiberglass) then hope for the best. Is it possible that the rubbery epoxy was just extra and that the epoxy actually holding the scales on is hardened normally?
And another thing, what sort of epoxy do you have?

mete,
It wasn't an accident according to the authorities, they're treating it as a crime scene. Hopefully the morons who are responsible will lose everything they have.
 
I had this happen to me once. Is your epoxy a slightly different color now than it used to be? This was the one thing I noticed about mine when this happened, it had changed color slightly and was a little more cloudy.

When I did some searching around for what happened I found the epoxy makers site which said that this can happen when the epoxy is a little old (about a year for me). All that is required is more mixing time when you mix the two parts together. Sure enough this solved the problem.

If the two scales are soft enough to pull apart I would take them off clean them and try again. Just mix the epoxy longer than normal. You could try a test before redoing the handle and see if longer mixing does the trick for you.

Good luck.

Sean
 
well the onley time i have had epoxy act weird on me was if i did not mix it corectley or not half and half, but for the most part its prety fool proof. i have also noticed if the epoxy gets to old each part will start to get clumps insidde of it. I dont use epoxy anymore i use JB weld, well i cant say i dont use epoxy any more because i still do a little. but one thing to rember is the faster the epoxy sets up the weeker it is going to be when its hard, like say a 30min is way stronger than say a 3min. also i like the longer set times so i have time to get everything lined up. JB weld takes 24hrs to set full
 
If possible mix the hardener and the resin separate, then use as normal. It is always best to mix as thoroughly as time permits. The components in each will settle if given enough time, say a year or more.
 
CanDo said:
mete,
It wasn't an accident according to the authorities, they're treating it as a crime scene. Hopefully the morons who are responsible will lose everything they have.
Click to expand...

From what I've read, the allegation is that the concrete contractor mixed down the fresh contcrete with cured contrete. The company claims it was still within the strength requirements called for by the designers. (That should be easy enough to prove if true.)
All I know is I can't imagine trusting those huge concrete panels to epoxied anchors. It may seem OK for now, but what about in 100 years?
There are a lot of impressive bridges and building from the 30s and earlier here in SO. Cal. and they've survived some big shakers. It's nice to know it's steel, concrete and good design when you're driving under/over them.
The concrete contractors might well turn out to be crooks, but my gut-level instinct is that there's more than one party to blame.
 
The epoxy went bad! If you store it in extremes of temperature it will go bad. It does not like high heat before it's mixed. The one sure sign of that, if you mixed it properly, is the rubbery feel.

I store mine in the house(kitchen cupboard away from the stove) and only take it into the shop to mix it up for scales. I've had batches of epoxy go bad by keeping it in the shop year round. It gets real hot in my shop in summer, and the opposite in winter.

In the winter I mix it in the house as well as let the knife scales setup there as epoxy doesn't like temps below 70-72 degrees when setting up. Heat will not bother it on setup.
 
It is Locktite Brand, 90 minute setup time. It was opened about a year ago, capped well, kept in my desk drawer and inside the house. I noticed the resin was a little stiff but not lumpy. I mixed it very close to 50/50 for a full minute, I'm sure it was mixed well. This is not the first time I ever used epoxy, nor the first time I used this brand. Actually I mentioned that I used this tube set about a year ago to make another handle and it turned out great. From now on I will buy a fresh package each time I start a project.

I held a heat gun on the handle for a few minutes this morning and it seems to be a little better. I tried to pry the scales apart and it held. I didn't try very hard, just enough to see what it felt like.

I am going to add some 1/8 inch SS pins along each side of the tang. This is a flat tang about 1/2 inch wide and 4/5 of the length of the handle with deep grind marks to help hold the adhesive. The scales/slabs are canvas micarta, so I think it will hold up well. Good thing I scribed the outline of the tang on the outside of the slabs.
 
If you choose to remove the scales you can put them in the oven at about 250 for a few minutes and they will pop right off.
 
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