Epoxy still soft after 12 hours...now what?

PIndelicato

PIndelicato

Joined
Sep 16, 2002
Messages
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I glued up 2 knives last night around dinner time. I emptied what was left in the tube of Loctite 60 min. epoxy into my little cup, stirred it well for a couple of minutes, and did the first knife. There was a bit less epoxy left than I had thought looking at the syringe, so I decided to open a new package of epoxy and mix up a new batch to avoid running out half way through the 2nd knife.

This morning I checked on things, and I found that the epoxy in the mixing cup from the first knife wasn't hard yet. That's strange...better check the actual knife. Stuck the overflow in a couple of spots with a toothpick, and it's still soft too. This epoxy worked great about a week ago and was recently purchased, so I know it's not old or anything. It's consistency is stiff, but soft...about like the natural peanut butter that you stir up to mix the oil back in, after it's been refrigerated.

What should I do, here? Should I wait more time (I'm not in a rush)? Should I try to hurry up and clean it all off and re-do it (assuming I'm even able to do that at this point)?
 
Not too sure about that one. It was a bit chilly last night. Low temps will slow epoxy curing, but that sounds a bit too long. Was this in the cold garage?
 
Mike,

It was on the cool side, but this was indoors and perhaps more importantly the 2nd knife/2nd mixing cup is nice and hard this morning.
 
I use west systems 105/207 and it often takes 24 hours. The loctite should take a couple hours at most. If it was cold it will slow the curing. Put it in a warm room and give it an hour. If that doesn't work, you may need to scrape it all off and start over.
 
Crap...just called Henkel, and was told this lot is from 2008. They said it might still set up and to give it 12 more hours to see. I know I bought this recently, and it worked great about a week ago!?!

If it doesn't and I have to redo it, is there something I can do to remove the epoxy and save the scales (along with the many hours of hand sanding/polishing on the blade?)
 
Yea, if it was inside I'm thinking your epoxy turned and you might want to pull it apart, clean it up and start over. Believe me, I've done it more than a few times for various reasons. Good luck!
 
You should be able to scrape most of it off and the rest might come off with solvent. Otherwise, a little sanding on the back of the scales should do it.
 
Your best bet would be to scrape it off and do it over. Even if it did harden, bond strength would be suspect. Acetone will cut most all epoxies, and shouldn't hurt the wood. Mineral spirits works also. Be sure to get it all out of the back side of the scales so the new epoxy has good material to bond to. 12 hours seems excesively long for a 60 min epoxy.

If you are selling the knife, would you feel confident knowing of this issue? Only to possibly have to rehandle it down the road?

I'm assuming you are using wood scales, so if you do try warming it up be careful not to go over 100*F to avoid any air pockets expanding too much and causing other issues later.


-Xander
 
fast14riot said:
If you are selling the knife, would you feel confident knowing of this issue? Only to possibly have to rehandle it down the road?

-Xander
Click to expand...

For primarily this reason, I went ahead and pulled it apart and cleaned it up. I was most worried about cleaning up the blade (and wrecking my hand rubbed finish), but the biggest pain was trying to get the epoxy off of the scales. 1/4 can of acetone, 1/4 bottle of isopropyl alcohol, a pile of rags and paper towels, and some carefully applied swear words later, I now have this. It was an absolute mess to deal with, but I'm glad I did it.

Thanks Xander (and everyone else who helped!)
 

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fast14riot said:
Your best bet would be to scrape it off and do it over. Even if it did harden, bond strength would be suspect.
-Xander
Click to expand...


This is a fact. Old epoxy, even if it hardens, does not have the bond strength of fresh epoxy. I have learned this the hard way. This was one of the primary reasons I switched to Brownells Acraglas, it has a five year shelf life.
 
I've thought about Acraglas in the past Nathan, but passed due to my low output and the availability only in large volumes. I didn't know about its 5 year shelf life, however, so thanks for making me aware of that. Just might pick some up after all.

Any opinions on the stuff from knife-specific suppliers, such as K&G?

Thanks guys!
 
Hey glad to see you chose to redo it. Better to take the time to do it right than to rush and later do it twice!

One thing you can do is buy epoxy "repair kits" to try the different brands. They are usually only a couple ouces or less and can mostly be found at marine supply stores. I don't think hobby type epoxies are available this way though. Most hobby epoxies are 1:1 while the more structural/laminating ones vary from 3:1 to about 5:1 resin/hardener ratio. Be sure to read the instructions as some are measured by weight, like West Systems for example.


-Xander
 
P J 234 said:
I've thought about Acraglas in the past Nathan, but passed due to my low output and the availability only in large volumes. I didn't know about its 5 year shelf life, however, so thanks for making me aware of that. Just might pick some up after all.

Any opinions on the stuff from knife-specific suppliers, such as K&G?

Thanks guys!
Click to expand...


I test my epoxy before using it on a knife to confirm that it hardens and that it has good adhesion strength. Doing this, I found my good areomarine epoxy had gone bad, leaving a lot unused (still hardened by they way). So, I went to lowes and got some of the 1 hour LocTite the OP mentioned and in testing it I found it had poor adhesion in my application. So I ordered some of the 30 min epoxy from Pop's (many of the knife shops have the same "stuff"). It worked well and had good adhesion, but it went bad within a few months. This is when I embarked upon an epoxy jihad, which ended with acraglas. It is fairly expensive, it is a pain in the ass to measure accurately (and this is critical), and it is thin, which makes it difficult to use. But it holds up well and is advertised as having a 5 year shelf life. I have only been using it for about a year, but as far as I can tell it still works like new. I ordered it directly from Brownells as a hedge against getting epoxy that might have been stored improperly.

By the way, it it really is Brownells Acraglas, not some commodity epoxy they buy and repackage. They developed it decades ago as a bedding resin to eliminate the need for hand bedding a stock, and it revolutionized that aspect of custom precision rifle building. It just also happens to work well on knife scales...

BTW, people's tests of the gel version indicate it doesn't work as well.
 
I had semi-settled on using the Golfsmith shafting epoxy from the Glue Wars thread due to it's performance, convenient availability at a local store, and very reasonable price. It dries black however, which is fine in many cases...but when it's not, I chose to supplement with small quantities of clear epoxy from the hardware store purchased as needed. (I'm not sure there are many local marine stores here in the AZ desert!)

Perhaps I should try the Acraglas next...
 
Nathan,

You mentioned that acraglas is thin, that is the one thing that i dont like about it. Does anyone know if you can thicken it by adding a filler like west systems colloidal silica filler, without making it weak ?

-John
 
The Acraglas kit comes with glass flock. The normal usage for the material is bedding for rifles .Mine have it and it's still there 40 years later ! LOL You mix in the flock to the consistancy you want .For rifles don't forget to put release compound [wax etc] on the metal parts !!! Saw that done and it's not pretty .
 
Well I am sure it can be thickened with #406 colloidal silica (aka "micro balloons") and not affect bond stength, EXCEPT in thin film applications such as laminating. Adding a filler just doesn't seem to work well when being used in "sandwhich" type joints, or laminating layers together. Adding the filler in thin film applicaions will allow less epoxy in a given space, think of putting a steel plate on top of a bunch of marbles. I imagine if used sparingly enough, one could achieve results with no discernable difference, but to get a thin epoxy to a thixotropic state you would need vast amount of filler.

Now that I am thinking about this, I would be more inclined to use one layer of 0.5 oz plain weave fibeglass cloth to try and keep the resin where I wanted it. It is thin enough that it shouldn't be visable when done right, and if the resin is clear, so will be the fiberglass. I may try this. Also what about temperature induced viscocity, I.e. mix it up and throw it in the fridge or freezer for a few minutes? I know it will thin out again, but it ma stay thick(er) long enoug to get it on where you want it.


-Xander
 
mete said:
The Acraglas kit comes with glass flock. The normal usage for the material is bedding for rifles .Mine have it and it's still there 40 years later ! LOL You mix in the flock to the consistancy you want .For rifles don't forget to put release compound [wax etc] on the metal parts !!! Saw that done and it's not pretty .
Click to expand...

Yeah the choppped strand fiberglass is great at creating a 3D matrix of reinforment, which works wonders in gap filling applications. So well that the one and only time I saw someone improperly inlet their stock and then try to glass bed it, I could hardly believe my eyes when they had to almost destroy the stock to get it off the action! Still made a few nice pistol grips though!


-Xander
 
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