Testing for the ultimate adhesive

[SteveS]

DaveL - You're welcome. I'm glad someone else is getting a kick out of this work.

OK I re-attached three pieces - just grind - no wash. DEVCON, JBWELD, Gorrila

Then I took it on a plane trip. 2 flights 4 hours each in luggage (you guess the temp and pressure - but I don't think it's any different than the cabin). Then a trip thru the dishwasher.

Then the IMPACT Bar test Bar test video - 700K

The DEVCON came off on the second impact. E-120HP came off too, but it was set after cleaning with Simple Green - so that's a nontest. However even after several BANGS! these remained:

Loctite Xtreme (wash with simple green)
Loctite U-05fl (wash with simple green)
JB Weld (no wash)
Gorilla Glue (no wash)

I need to start over so I took to pounding the blocks off the steel. Oh baby

Xtreme came off, but it took more than a few good wacks - pretty darned good for not being a 2part adhesive.

U-05FL stayed on longer and took more hits

Gorilla Glue took several whacks the the dymond wood did a lot of chipping before it came off.

The winner was JB Weld:



As you can see it never came off. The dymond wood is coming apart before the JBWeld gives up.

To the left is the Gorilla Glue sample, to the right is DEVCON.

Because of the simple green problem the only results I can confirm at this point is:

DEVCON doesn't hold real well after the dishwasher/plane flight

Gorrilla Glue holds really well

JB Weld glue seam on steel is stronger than dymond wood.


Steve

[tmickley]

Devcon 5 minute half fails.
I pulled my test piece from my heat treat oven that is in my cold garage. The last heat cycle was 175F for one hour last weekend and since then it's been around 20f to 40F in my garage. I took it and whacked them all again -- which I'm starting to enjoy -- and we had half of a failure. The Devcon 2 Ton failed early, today the Devcon 5 minute half failed. Just about 1/2 of the test piece of broke in half and popped off aftera couple whacks.

The ones people have been rooting for, Acra Glass and shafting epoxy still look very good. The wood is getting pretty chipped up the rest are still holding strong. So far, if you can manage the mess, gorilla glue looks pretty good between both Steves tests and mine.
Personally, I'm rooting for shafting epoxy.

I just put the test piece into the dishwasher. I'll keep you posted.

Steve, let's hope you use all of that dymond wood up in these tests so it never ends up on a knife handle..

[tmickley]

I should have gotten a picture of this because it was amazing. The Loctite 324 speedbonder test piece between two metal strips held 100lbs! This was glued up like the sandblast vs scratched test pieces posted earlier. All of the others failed betwen 75 and 100lbs. This stuff held 100lbs and the metal started bending to nearly 30 degrees. I think this would have held until the metal bent completely over but I started moving it around and the bond broke. I immediately glued up another piece so I can verify it and get a picture this time. It is unfricking-godly expensive at $14.66 for 1.69oz or $200 for 33oz and then it requires an activator for another $20.


Here is a description from www.McMasters.com

For parts requiring high-strength adhesive and jobs requiring high impact resistance. Begins to harden in 5 minutes. Shear strength is 2175 psi. Fills spaces up to 0.040?. Temp. range is -65? to +275? F. Note: Adhesive must be used with Activator 7075?
For nonporous surfaces like magnets and mirrors to steel housings

[tmickley]

Last week I left the test piece in my heat treat oven for 1 hour at 175F and there it sat all week. It?s warming up here in the spring so the garage has been in the 20?s and 30?s. I brought the piece in to whack it. The Devcon 5 minute epoxy half failed. You can see 1/2 of it broke off, the other half is still hanging in there. All the others took the beatings. Then I threw the whole thing in the dishwasher. This is where I had to explain what I was doing to my wife. Even with all the goofy things I tend to do, she knows better but this one still forced her to ask why I was doing this (it's her dishwasher you know). "To see which one holds the best" was my answer. After the dishwasher cycle, I took the piece down and whacked it some more. Keep in mind, this is all with a large framing hammer and I have long since stopped tappjng these things I am giving them 3 or 4 good thumps each time. Two more failures to report, the Permatex and T-88 epoxies both fail. The Permatex came loose in the dishwashwer, the T-88 got tired of getting beatings and gave up.




The T-88 failed by 3/4ths. A quarter of the test piece is still attached and I?ll leave it that way just to see how long it goes. The most usable leaders at this point are Acra Glass, Golfsmith Shafting epoxy and oddly - metal superglue. The polyurethane glues, I believe will with stand all of the tests better than any of the others but it appears to be a horrible product to work with on a knife - it?s fine for wood working. On the other hand, maybe it's time to focus a bit on the polyurethanes a bit more. The drawbacks to the poly glues are, they cure a light brown or dark honey color; it really expands, you'd have to really clamp it down, but then who doesn't have plenty of clampls for one knife handle? Then you need to ask, if you clamp it down very firmly, does it still have the holding power? I bet it does. I'll have to test that... For the money, ease of purchase, general availability, toughness to date in all of the tests, the polyurethanes are looking very competitive. Be warned, if you get any on your fingers you will have stained hands for days.

[SteveS]

Tracy you're the man. More great tests.

The 324 stuff sounds awsome.

I still have very high hopes for E120-HP. It's not as expensive and is really handy with that applicator gun. I think it will compare with the 324. Even with the simple green problem it has always held longer than anything else.

Now that I have the bar cleaned cleared off, I'm going to run more tests (without the 'green').

It is quite confirming that we both had the same results with DEVCON - one of the first epoxies to fail.

Regarding the urethanes, I have U-05FL. It expands a little (not nearly as much as Gorilla Glue), as easy to clean up as epoxy and holds better than most of the other epoxies I've tried. The best part is it stays flexible. This is important with differing materials. Also, the flexible products withstand impact better, even tho they don't hold as well. This might well be my choice for natural materials (this or Xtreme Repair.)

Keep reporting !!

My next test is only going to have the impact bar test. But my plan is to do lots of environment tests.


Steve

PS you got me laughing about the dymond wood. I have two more slabs to use up. Funny I was hunting for something to test with and came across this stuff in the bin. Now I have a use for it!

[justice]

i love this thredd!! ive been back 2 and 3 times a day since it started.
tmickley

Be warned, if you get any on your fingers you will have stained hands for days.

yea i can verfy that!
care full with clothing as well!!
by the way these tests are kind of conferming my thaughts. i was always leary when it came to using devcon.


ps. we should get a paypal account for you guys so we can help fund this thing(and more like it in the future) i got about $18 sitting in my paypal account doing nothing. im willing to chip it in.


...justin

[tmickley]

Justin, I wish I could say that I've stayed away from Devcon, I've used it for years. I recently stopped however -- just after I saw it fail in both Steves and my tests. Chuck Bybee of Alpha Knife Supply sent me a box full of wood and metal along with a few adhesives. The adhesives are paid for so no need to send anything - but you are buying the beer if we ever bump into each other...

The only dual tube dispenser type of two part epoxy that is still in the game is Super Glue brand Metal epoxy. This stuff comes out and cures silver looking so in theory it should be less noticable in the glue line.

[Chris Daigle]

Question for Tracy and Steve. One of the drawbacks you are mentioning with several of the products is the color it takes on while curing/drying. I have used epoxy colorant to match liners in the past. Do you think adhesives like the Acra Glass could be dyed, and if so, would it change the strength of the bond??? :confused:

Chris

[SteveS]

Chris,

My acraglas kit came with brown and black dyes. I don't think it would have an effect. It's part of the deal with gunsmiths to color the stuff before using it for glass bedding.

Justin,

Thanks for the offer. Chuck doesn't like me any more I guess . Fitzo sent me West Systems Epoxy for free! I had to pay for every thing else. Don't worry about it, most of it I'll find uses for around the house.

FWIW, last night I prepared a new test bar. I ground everything off with a worn 50 grit. Then sandblasted the bar. Then went back to using C clamps to reduce the glue line. I still want an adhesive that holds well but doesn't leave a line.

Steve

[tmickley]

Originally Posted by Chris Daigle

Question for Tracy and Steve. One of the drawbacks you are mentioning with several of the products is the color it takes on while curing/drying. I have used epoxy colorant to match liners in the past. Do you think adhesives like the Acra Glass could be dyed, and if so, would it change the strength of the bond??? :confused:

Chris

In another life and hobby, I studied building composite home built airplanes. It is routine practice for home builders to add an inert material such as glass beads to bulk up epoxy. These guys are necessarily extremely conservative about safety issues. If adding a 'filler' doesn't compromise the epoxy for them, it won't for a knife. I've used both liquid and powder based dyes. The powder, I think, can be considered totally inert. The liquid not far behind but I am less positive about this. It takes so little of either to dye a color that I don't think anything less than underwriters lab could possibly measure any negative affect it might have.
I do see people mention thining their epoxy with acetone and I know from experience this will weaken epoxy.

Speaking of Fitzo, he must be squirming in his chair about our testing methods coming from his background. Mike, when I am rooting for one epoxy to win over the others, is that bad???? When are you going to help us out with at least one method of testing?

[Lane Ritter]

Devcon worked great about 5 to 6 years ago, for me anyways. No failures on those knives, or while putting them together.

I recently started making knives again. The epoxy isn't sticking to the metal like it used to. After leaving the handle material and metal clamped together for a few days. Alot of times, I get a complete failure where the metal and epoxy meets. It isn't sticking at all.

I use the same method of cleaning and prep that I always did. I rough it up good, with coarse sandpaper, and even scratch into the metal with a file.

Could it be, that devcon tweaked their ingreadiants. Or maybe I was just lucky with the stuff in the past.

Lane

[fitzo]

Originally Posted by tmickley

Speaking of Fitzo, he must be squirming in his chair about our testing methods coming from his background. Mike, when I am rooting for one epoxy to win over the others, is that bad???? When are you going to help us out with at least one method of testing?

I think you guys are doing very well, IMO. You are concerned that the various materials be tested fairly, despite perhaps having a favorite. You have my continuing interest.......

[Ray Rogers]

I think this is a wonderful thread and have been following it with great interest. But, I wonder if you are testing for the correct characteristics. It seems to me that the majority of testing is placing the emphasis on shear strength and, in my opinion, that is not the most important characteristic for an epoxy used on a knife. I say this because scales are not held on with glue alone, there are always pins or screws which would have to be overcome before the shear strength of the glue would start to be much of an issue. This is why we say that the glue is not a structural component of the handle, it is there to seal out moisture (you can see that sentiment in a lot of threads). So, while i think the shear strength test is important and informative, i would suggest another test more suited to the type of force a knife handle might be subjected to.

One test might be to glue some handle sized wood to a piece of steel at least 12" long. Then, slam the side opposite the wood down on a flat hard surface and see if the wood can be made to pop off.

Another test would be to glue steel to both sides of a piece of wood. The steel would have eyes welded on it so that the test piece could be secured to a stand and the weight could be attached to the opposite side (or hydraulic force could be applied with a jack) in order to see how much force is necessary to pull the steel off the wood.

In either of these tests and also in the shear testing you are doing, the results might be even more meaningful if you cleaned the bead of glue off the perimeter of the wood/steel bond. Knife handles don't have large beads of re-inforcing glue on them and that could be a significant factor.

Whether you do these tests or not I look forward to seeing more of your results ...

[SteveS]

Ray,

You and I on the same thought process. I'm worried about how they hold up to abusive environments (heat, cold, damp). Tracy is too.

The shear strength tests he's doing are for fun. I wipe the beads off the sides of the wood. BUT again I'm not trying to test the best way to construct a knife with these tests. Just trying to find the best for sealing them on the long haul.

For example, JBWeld is definately very strong. I won't use it for slabs 'cause it shows and I don't need strength. On the other hand DEVCON is certainly strong enough for handles, but if it gives up after a trip thru the dishwasher I'm not expecting it to last years and years.

Make sense. I'm using an impact test. Why? not to find the strongest, but if an epoxy lasts fine when fresh, but fails after some time in the freezer it's a failure.

See we are trying to find out the same thing you are concerned about.

Steve

[DaveL]

There is no doubt that most of us have adhesives we have used, like them okay and really wonder why ours is not being tested. But this is a great thread as I have said before and any result is far from what we know at this moment. I applaud the agony and pain the testors are going through and am very anxious to see the finals. This is my favorite thread as far as what I look for first and I expect it is on a lot of maker's reading list now. My hat tips once again and I am waiting, just a little breathless....