Strongest Epoxy On The Planet

camojoe

Member
After reading countless epoxy threads on this forum and others, I am attempting to gather some links to further the discussion. I would like to find tests that offer hard conclusive data conducted by a third party if possible. After reading the great ''Glue Wars'' thread it seems there is no ''best'' epoxy for all materials so the search continues. :biggrin: Feel free to post any links to manufacturer data or new products you have discovered.

This ''lap-shear'' test includes the popular West Systems epoxy

http://www.jcrocket.com/adhesives.shtml

More data from the same gentleman.

http://www.rocketmaterials.org/datastore/fins/Tension/index.php

NASA approved, it must be good right? :9:

http://news.thomasnet.com/fullstory...Epoxy-passes-NASA-low-outgassing-tests-595049
 
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the glue wars showed that epoxy does not have great adhesion to metals. The locktite material came in first place and a popular urethane glue was almost as good.

I made some w2 kitchen knives and glued on the scales leaving the pins off. After a few weeks of daily use the epoxy released from the metal. The urethane glue lasted a year and only released because the metal rusted thus lifting off the adhesive.

ernie
 
oh thanks clancy ,i dont like to hear that the only reason i even use any glue or epoxy is to keep moister out to keep it from rusting, back to square one.1 year well better then nothing!
 
Surface prep makes a HUGE difference. Mediocre adhesive with great surface prep can out easily outperform great adhesive if the surface prep isn't good. Having said that, some applications call for different adhesives or we would all be using Elmers School glue. The technology continues to get better and we should all be constantly on the lookout for new, better adhesives. Good thread.
 
good point boss....bad surface prep will show right away. Sanding works about as good as anything. Be careful in handling finger oils do not help adhesion. Cleaning solutions can cause problems with residues, one example is Windex it leaves a silicone layer on your window so dirt won't stick. That is about the worst thing for adhesion.

ernie
 
ok witch one seeled out the most water, thats what im looking for i do loveless bolts on my handle slabs but dont want anything rusting under slabs, whats your suggestions on that? and would surface grinding with a stone be good prep cuz i now im not getting a sand blaster anytime soon?
 
Locktite blackmax 380. I have used this stuff for years to fasten barrel bands for swivals on rifle barrels. Hasn't failed yet. This is some very tough stuff! The only downside is you better have your act together cause you don't have much working time to play around.
 
In that "Wood in the Kitchen" test that I did, I was focused on treatments for the wood - but decided to see how Loctite E-120HP would do. E-120HP al$o require$ a $pecial plunger/applicator $eparate from the glue tube. I ground the 5160 bars to maybe 400 grit? and cleaned them with acetone. Which blocks popped off in my torture tests seemed to have little to do with whether that particular wood block was oil-free - more to do with whether the particular block took on water and warped. Bizarre thing: one of the best performers was plain safflower oil.

Makes me curious about whether some glues aren't as sensitive to having a pristine surface to bond with. I would have though that the blocks with undried oils would have popped off pretty easily.

Eric Ochs did a similar handle material torture test - used Devcon 2 ton for the glue - and had the blocks popping off after a few months (admittedly it was a nasty test - but that's how you find out things in a short period of time) here's the link: http://www.ochssherworx.com/index_files/Page513.htm

Caffrey mentioned in a post that most retail epoxy has a hold life of just a few years - while West systems is rated for 5 year shelf life and 25 year hold life... and Acraglass is rated for 10 year shelf life and 50 year hold life.

Gene - thanks for the note on K & G epoxy - do you have a feel for how well it keeps a bond over the years? They say it has "unbelievable" strength - is it up there with JB Weld?

Great thread!! Looking forward to seeing more comments...
 
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My brother works in the adhesive industry, making custom adhesives for a variety of applications, mostly labels. Adhesives are engineered for a variety of purposes--some are designed to be more permanent than others, etc. Also, they are engineered for different physical properties. You can have a glue with good adhesion, but poor shear strength, etc. You can also have glues that are great for adhering to one material, but not another. The glues sold to be "general purpose" (hold multiple types of materials together) often do not perform as well as those engineered for a specific material. So, you might find one that works great for wood to metal, but might not perform as well for micarta/stablized materials.
 
West systems has been designed for building boats, I use it by the gallon in my sign business. It has not done well in my tests on knives. So I always use Gorilla glue.

As for keeping all water vapor out that is an impossible task, for any adhesive. I worked in research where we had to package water sensitive materials, the best we could do is use a silica filled epoxy to seal gaps in an all glass enclosure. This slowed water uptake long enough to allow a 6 month shelf life. In use we had to keep the unit inside an oven that provided a dry environment, this gave us a 10 year operating life.

ernie
 
Two part epoxy is used to best effect by prepping the materials to take advantage of a mechanical bond over a chemical bond. This would be especially true on non porous materials like metal. Wood will absorb epoxy so it bonds very well, metal must be rough to give it grip and clean to promote adhesion. I score metal deeply with an engraving bit and sand with 60 grit to give the best bond. Drilling divots into the tang would work well also. Most of the epoxy bought at the hardware store is silica filled to make it thick, pure epoxy is much thinner giving it a better bond to wood as it penetrates deeper but it as less strength in filling gaps for nonporous materials. I go for a mechanical bond on a marine grade and it has never let me down yet. Not only would the adhesion have to weaken but most of the cured epoxy would have to shatter to free it from being key holed into the grooves and divots. To be fair though on some handles I didn't use any adhesive at all. I used bee's wax to add some measure of moisture protection to the tang and peened the pins over washers to form hand peened rivets, they're attractive and easily tightened if necessary, but this has been only on old knives given to me for conservation or restoration.
 
Ernie,

When you use the Gorilla Glue, how much pressure do you clamp with? I think I read somewhere that The Gorilla Glue works better if the layer is very thin and good clamping pressure is used. When I've used it on wood, I clamp it very tight and have gotten good joints.

I am making a small neck knife that I am thinking of trying the gorilla glue on. I will use some maple for the scales.

Ric
 
I use gorilla glue as well but not yet on attaching scales to the tang. I use primarily as a heavy laminate adhesive, medium to large splice joins, or in heavy structural joints in furniture. The thing is it expands as it cures under pressure and once cured it is a bear to clean up. The squeeze out doesn't sand well, or pair off easily. I am working on a smaller bowie now that I want to add bone scales to. However I think they might be a bit too thin for a comfortable grip. I may laminate a 3/32 cherry liner to the bone scales, if I do I'll use gorilla glue as the squeeze out will be cut off as the blank is trimmed. If your using it for attaching the scales to the tang you'll want to watch it for at least an hour as it is clamped to wipe the squeeze out with alcohol as it forms. Also you must clamp firmly and evenly. The expanding action of the glue will lift whatever it can. I'd do one at a time waiting for full cure before adding the second. I haven't used it to bond to metal but it does make a very strong bond where I have used it.
 
As for keeping all water vapor out that is an impossible task, for any adhesive.

That statement makes me very uneasy. I rely on mechanical fasteners to hold my knives together, but would really like to find an adhesive or sealant that I can promise will keep moisture out of the mating surfaces.

One thing I notice about manu's specs about epoxies is, they're very impressive when "gluing" wood to wood or even metal to metal... big deal, I'm not making plywood here! :D
 
James,

Sorry to carry on but I spent the last 40 years in microelectronics processing and research. So please forgive me if I pontificate.

Almost all polymers and even dense plastics do not stop water vapor from migrating through. The rate is very slow but measurable. Even a sealed plastic milk jug of water will allow water vapor through and after a few years all the water will be gone. I left a tupperware container of ferric chloride in the back of a cabinet my shop in 1994. I found it in 2010, and when I opened all I found was thick barely wet sludge. You would not expect all that water and HCL to evaporate through the plastic but it did, (of course all I had to do was add some HCl to the iron oxide sludge and it was as good as new).

A thin layer of metal or glass will make a surface impervious to gasses and water vapor, that is why your potato chip bags have a thin layer of aluminum coated on them to seal out oxygen and water vapor.

There is one material that is very good at stopping water vapor, parylene. It can be vapor deposited in a heated vacuum chamber and it coats every surface with a microscopic layer that repels water. The layer is transparent and relatively scratch resistant. It is also expensive and makes a surface relatively nonstick. It is used in medical devices, military applications and electronics. For example you can vapor coat a circuit board and improve it's reliability in humid environments. I looked into it for stabilizing knife handles but decided it was too expensive.

You can read about it here http://www.scscoatings.com/parylene_knowledge/history.aspx

ernie
 
That parylene has very desirable atributes & no undesirable ones as far as I can see. Too bad its so expensive. Ernie do you think it will ever become cost effective for our uses?
 
I talked to a top guy at SCS and he said they do have a coating sevice. Their most scratch resistant coating would not hold up on a blade. It would protect the tang from moisture and provide a non stick surface.

The vapor would penetrate most handle materials and coat it with a microscopic layer that is waterproof. I think the result would be a handle that would pick up water but not be affected by it. No expansion with humidity.

As I recall the price per basket of parts to be vacuum coated was quite high.

ernie
 
I have also messed aroung with several types and found that surface prep is the most important. Leaving a perfectly flat surface may not be best either, I have recently started grinding grooves and slots and even small holes and or thru holes in my tang ( I only make full tang knives) to give the epoxy a place to grab! I was using a 3-m product d-p 100 I beleive but have switched recently to a loctite epoxy and am happy with the results so far! Always looking for new info.......
 
Interesting alternative I found posted on another site. http://solutions.3m.com/wps/portal/3M/en_US/3M-Industrial/Adhesives/Product/Bonding-Tapes/VHB-Tape
Actually a tape that seems to have some great bonding properties. This may be ideal for smooth scales such as corian and resin blanks.

On a side note, I have been using G-Flex epoxy for all my wood scales and found out the hard way it has a great bite. After gluing some scales on inside out, I attempted to knock them off with a baby sledge. No dice. I then soaked them in mineral spirits followed by VM&P Naptha (only solvents on hand) and additional hammer strikes. Scales never budged so I ended up drilling holes parallel with the blade along the entire length of the wood. Hammer/chisel finally freed my poor blade. After scales were removed it was evident the epoxy had penetrated the wood. I was left with at least a 1/16'' strip I finished off with my dremel.
 
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