Testing for the ultimate adhesive

[SteveS]

tmickley and I love everyone here. But, there are different factions among us. "What?" you say. "How can that be?"

The difference is adhesives. We put our faith them. We trust them when the chips are down (or the pins are loose). And we follow our favorite blindly, never having the time and money to try the vast array that?s available.

So, Tracy and I have set out to dispel the myths. To end the dispute or maybe we just want to stir up the pot .

Tracy and I are testing a variety of adhesives (not all epoxies) to see, as best we can, which ones will hold up the best for standard knife construction.

Please note we?re not about to compare HOW to construct a knife. That?s a religion of a different color. We?re only setting out to see how certain adhesives perform under a variety of conditions. For example, one adhesive might have better shear strength or peel strength than another. But it?s thick and ugly and no one would use it on a knife. One might hold well at room temp, but fall apart in the snow.

Because we?re testing epoxies and not methods, we?re using blocks of whatever simply attached to steel ? no bolts, no peening, no hidden pins, just epoxy testing.

Tracy and I are also using different methods and tests and conditions. I believe this will help evaluate the results.

Given that, let the games begin! So, belly up to the bar and place your bets!

And may we all learn a new thing or two.

Steve

[SteveS]

So here are my contenders:



1. Loctite Xtreme
2. Loctite U-05FL Flexible Commercial Adhesive
3. DEVCON 2 Ton Epoxy
4. Loctite E-120HP
5. JB WELD
6. Acraglas Gel
7. West Systems Epoxy (10 min Pot life)

Process:

I 'glued' the samples to a single bar of ATS-34 hardened to 60HRC. The bar was roughed up with a new 80 grit belt. The bar was then scrubbed with Simple Green, then sprayed down with Brake Cleaner.

The samples are dymond wood abraded with a 36 grit disk.

The clamping was done with hand clamps - loose enough that the block could be slid underpressure fairly easily.

This was done on Tuesday, March 8th at 9PM. Curing started with a light bulb over the sample to keep it warm over night. It's been at room temps since then (68 to 80).


Steve

[chrisinbeav]

There is one adhesive I would like to try. It's made by a company called Fusor. Typically they make autobody adhesives not knife adhesives. There is a particular one that is for panel bonding. (panel bonding...the adhesion of outter non-structural or semi-structural parts body parts)
I figure if this adhesive is crash tested, which it is.... shouldn't it work on a knife? The only problem... it's kind of a pale green color when dried and it has micro beads in it. The beads ensure a layer of adhesive between two panels. It might be a bit too thick though for custom knife tollerances.

Chris Nilluka

[SteveS]

Thursday, March 10th 10pm.

I ground the samples flush with the steel. By evaluating the glue lines I've found:

1. Loctite Xtreme:

It's a thick gel like stuff. Hard to get smooth coverage. It needs a good squeeze. But the glue line looks fine.

2. Loctite U-05FL Flexible Commercial Adhesive

This stuff is a urathane (sp?) adhesive and bubbles/expands while it cures. I've used it before and learned it requires heavy clamping to keep the glueline looking good. With light clamping the glue line doesn't look so hot.


3. DEVCON 2 Ton Epoxy

Glue line is fine, but under microscope there some tiny gaps on one side - and I mean tiny. Maybe I didn't apply it perfectly right there at the edge.

4. Loctite E-120HP

Looks fine.

5. JB WELD

Leaves a thicker glue line and is visible on one side. It's thinner than I thought it would be, but will probably always show something if used for handle slabs. It's visibly not the color of stainless steel.

6. Acraglas Gel

Looks fine.

7. West Systems Epoxy (10 min Pot life)

Looks fine.

Steve

[SteveS]

Oh Yeah, I forgot to note. In a previous round I tried silicon, a commercial super glue, and Gorilla glue. The only one that survived was Gorilla Glue. That stuff, I believe, would make a great adhesive for knife handles. However, as it expands it makes an icky, stick foam. If it expands onto the ricasso, I don't I'd ever get it cleaned up. And you'd have to watch for a long time as it hardens. Once that foam hardens you have to grind it off to remove it.

So, it's off my personal list of usable products. If you can deal with the mess, I'll bet it'll make a great glue.

Steve

[Chris Daigle]

Steve, in your photo you show a bottle of Gorilla Glue. Are you going to include it in your testing? I had always wondered about that stuff and their claims.

Chris

--------------------

EDIT: you just answered my question! Thanks.

[tmickley]

I have three kinds of polyurethane glue, including Gorilla glue, curing now. I'll start posting some pics and progress this weekend. Steve has done one round of testing already. He's on round two. I'm on round one. Chuck Bybee sent me some metal and wood to use for round two. Currently I have 15 kinds of adhesive curing now.
Here's a starter pic with part of the first batch:

[Ray Rogers]

I think this is a great test and look forward to the results. Thanks for doing this.

If you get the chance, try some of K&G Finishing's house brand of epoxy. I've heard some say it is similar to acraglass. It's ivory colored, quite thick when mixed, and incredibly strong. The only downside to it is that it must be mixed by weight rather than by volume....

[SteveS]

Ray, You're welcome.

I'm having way to much fun with this and it's nice here in CA. Tracy.... well he doesn't have anything better to do this time of year

I can't wait for the results to start coming in.

Steve

[ragnik]

Great test guys...I am anxiously awaiting the results!! On a side note....I have read of some folks using golf club shaft epoxy or glue...anyone ever try that stuff....supposed to be real tough...which makes sense since they are attaching golf club shafts to the club heads. Just a thought.

Ross

[Ed Caffrey]

A few things to think about when considering the adhesives are:

1. What is the shelf life of the product? (most of the "epoxies" are only 6 months) If the shelf life has expired the two parts will not mix properly, giving you only a fraction of the advertised "hold."

2. What is the "hold life" (how long before the adhesives starts to chemically break down after it has been mixed and cured)

3. The adhesive's ability to tolerate moisture. (I found that the devcon "waterproof" is not really waterproof)

It's no secret that I prefer the standard Accra-Glass, mostly for the reasons listed above. If the testing lasts that long, I suspect you'll find it doesn't reach it's full hold strength until about 5-7 days after it's applied, but if the testing were to go on for a number of years, the 50/50 mix epoxies would start crumbling and falling apart at about the 4 year mark. Put them in direct sunlight, and that time would be reduced to about 1 year.

Maybe I just look at it differently, but for me it's not the inital "hold" that sells me on a given adhesive....it's whether or not it's going to be holding 5-10 years down the line.

I'm looking forward to seeing how the results of this test come out.

[Ray Rogers]

I agree with Ed's points. That's why I like the K&G epoxy. So far, I've repaired a mirror on my Jeep with it (so it's in the sunlight and weather), used it to seal a cracked cast iron fuel pump on my 50 gallon gasoline storage tank (outside, in the sun), sealed up a massively cracked water pump housing on a 2 hp gas powered water pump (works great now), and sealed the argon gas port on my Paragon oven (inside, but subject to about 150 F continuously when in operation). All of these repairs are at least one year old and some are several years old. Also, I have had the glue on the shelf for two years with no noticeable loss of performance. I've never used Acra-Glass but it seems to be similar from what I've heard....

[SteveS]

Ed and Ray. The time issue is exactly what I'm worried about - not really holding strength - we're on the same wave length. And your real results are more important.

I'm hoping to subject the samples to stuff that will speed up the aging process.

Steve

[Gary Mulkey]

Steve,

Curiousity, for the super glue that you tested was it the typical thin glue or the gap filling gel?

Gary

[tmickley]

Here is the list of adhesives I am going to beat until they fail.
2 part epoxies
T-88 2 part epoxy
Clubmaker Shafting Epoxy from Golfsmith
Acraglas
JB Weld
Devcon 2 ton
Devcon 5 minute
Super Glue brand Metal Epoxy
Anchor Tite brand Marine

Super Glues
Loctite 416 superbonder 41650
Handibond Rubber Toughened Super Glue

polyurethanes
Elmers Probond
Gorilla Glue
Elmers Ultimate glue (looks identical to Elmers Probond)

others
Tanners Bond contact cement
3M Hi-strength 90 spray adhesive
my wifes hot glue gun

Some others I just found in some local stores that I will be trying out
loctite contact cement
Super Epoxy by PC Products
PC-7 epoxy paste by pc products
All Purpose Welder
Liquid Nails 2 part epoxy Perfect Glue 3
Elmers Craft Bond Ultra Stix All