JB Weld Vs. JB Kwik???

Michael J. Spangler

Michael J. Spangler

Joined
Oct 8, 2003
Messages
2,181
so whats the difference??? i've used JB weld before and it was awesome but i tried JB kiwk today and the piece of metal i bonded came apart as if they were held together by bubble gum. i'm not sure if its the JB kwik or not.
 
Generaly speaking, the faster the epoxy cures, the more brittle and weaker it is. Epoxy does have a shelf life, so it may have been an old batch.

I've used JB kwik before and found it very strong, though I wouldn't use if for knife gaurds as I like a little more time to clean up the joint before it's fully hardened.
 
Michael,
Everyone knows I'm a strong advocate of JB Weld for sealing joints, but I'll be the first to tell you not to use it if bonding strength is the primary thing you're after. I use it for guards on hidden tang type knives to seal the joint, but not to hold the guard on.

I like it because of the easy cleanup, and no chance of rust spots down the road from hidden, trapped flux. Yes, it has a strong bond, but that's not why I use it. It is good for sealing the joint because it is impervious to water, gasoline, chemicals, and acids.

But to answer your question about the the difference between JB Weld and JB Kwik, well it's the set and cure time, the tensile strength, and the amount of resistance to heat. Here's the run down:

JB Weld
Properties (lbs/psi)
Tensile Strength: 3960
Adhesion: 1800
Flex Strength: 7320
Tensile Lap Shear: 1040
Shrinkage: 0.0%
Resistant to 500º F

JB Kwik
Properties (lbs/psi)
Tensile Strength: 2100
Adhesion: 1800
Flex Strength: 7320
Tensile Lap Shear: 1040
Shrinkage: 0.0%
Resistant to 300º F

I use the JB Kwik sometimes, but you don't have time to fool around. You've got to get that sucker on there and get it cleaned up pronto. Now if you are trying to use either one of these in place of brazing or welding a tang, get that idea out of your head.
 
Terry,

Excellent specs you went to the effort to post.

I have had great difficulty getting JB Weld and some other popular off the shelf epoxies to bond to metalics and some other materials we use. Nickel silver and micarta are examples. I spend a lot of extra time machining cutouts in handle scales and drilling feed through holes in full tangs to allow the epoxies to interlock rather than depend on them bonding to the steel and adjacent materials. If not soldering, I dove tail bolsters (not as we normally think of it but rather with a dove tail mill) to accomplish the same as described above. That allows the epoxy to flow from within a bolster to and into the other through a couple pass through holes in the tang. Instead of bonding, or depending on bonding, it locks all things together. I am looking for a less time consuming method and I suppose penning would be the better choice with epoxy as a sealant, expecially for such things as bolsters.

RL
 
I use JB Weld for attaching handle scales to full tang knives in combination with pinning or screws. I use Vise clamps to hold them in place. I find this squeezes out any air bubbles and creates a stronger bond. I do one side at a time, and allow the piece to set for 24 hours before removing the clamps. This creates an excellent seal between the tang and the scales. The JB Weld gives you more time for adjustment. I thought about the other product mentioned but saw it didn't give you much time to work.
Scott
 
hey thank a lot for the info.... really in depth and just what i was looking for. well i figure i can just take off the guard and re braze the tang again. whats a nother shot at soldering the guard anyway? just some more practice for me. i wouldn't mind hand rubbing the blade again anyway.
all to be done tomorrow after this rain clears up.
thanks guys! :)
 
One thing I have found is that JB weld is too thick. You can thin it quite nicely with acetone. You can make it thin enough to pour but It takes much longer to setup, however when it does set up it seems to be just as good as when right out of the tube. No real intrinsic data but just my observations.

Jerry
 
One thing I have found is that JB weld is too thick. You can thin it quite nicely with acetone.
Click to expand...

Interesting, I might have to try this sometime. Thanks for the idea.
 
Interesting, I might have to try this sometime. Thanks for the idea

That's an old body shop technique and it works quite well. It also works well when you are filling a large void like a bone.

One thing that I think was missing from Terry's specs was the heat range. JB Quick will not handle nearly as much heat without breaking the bond. Both are good, just pick the right one for the job.
 
A few months ago I bought some of the Kwik and was surprised when the parts that I used it on came apart like was described by someone else. I mixed some more of it and let it set for several hours. Evidently it was old because the amount that I let sit never did harden. It stayed flexible and you could bend it in a complete circle without it breaking. I had a fellow show me something interesting the other day that had been done with regular JB Weld. It was a piece of metal that a machinist had made a mistake on in maching a sight mount on a 1911 model Colt .45. One of the old ones. It was an unusual design for mounting a Bo Mar Sight. He had made a mistake and had a piece that could be put back in a groove, in order to camofloge(sp) the mistake. The piece had been put back in with JB Weld about 8-9 years ago and the owner estimated that there had probably been around 30,000 rounds shot in the pistol since that time. He does competition shooting. He said that the piece has never shown any sign of becoming loose. This was interesting to me because I do a lot of .45 shooting myself and am aware of the amount of beating the slides take on these pistols.
 
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