Chemical bond

schmittie

schmittie

Joined
Nov 28, 2009
Messages
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What do you prefer for your handle scales? I've used both CA and epoxy in the past. I personally don't have much faith in the 5 min epoxy, so that's out. I really like the idea of using CA because I can finish the knife in one night as opposed to using epoxy and clamping it overnight. But what do you think? I don't have enough experience to say that one is better that the other, or that there is no difference. Please share your experience.
 
I prefer a 30 min epoxy just for the fact that it takes lateral stress better. I finally got two handles fit well enough that the pins alone held it together but I still used a small amount of epoxy just for my peace of mind. I use CA mostly for holding scales together while shaping and drilling the pin holes and for a hard finish on handles.
 
Last 2 knives I used gorilla glue and it worked ok, any gaps in pin holes or on the tang edge doesnt finish right cause the glue foams. This 3rd knife I used the 2 ton epoxy and really like it so far.
 
I have found nothing that works better than brownell's acra glass. west systems was found to be equall in a glues test a couple of years ago. search for glue wars if you are interested in readingabout them.
 
My personal opinion is that CA alone would be the least desirable for knife handles. Heat, cold, and shock can easily break the bond. Combined with mechanical fasteners, it MIGHT be viable.
For several years I used 2 part epoxies, but after having several knives returned with "loose" handles, I started doing some research and found that most of the commercially available 2 part epoxies are specifically engineered to start breaking down after about 5 years. Further more, their shelf life is approx. 6 months from date of manufacture. That information came to me directly from a chemist who worked for a well known epoxy producer. When I told him I was shocked to hear that, his reply was...."We're in the business of SELLING epoxy, why would I create something that lasts forever?" "I want you to have to buy more of our product!"
After searching around an trying various things, I now exclusively use Brownell's AcraGlas. It has a 10 year shelf life, and a guaranteed hold life of 50 years, is totally waterproof when cured. Another product that many knifemakers use and love is West Systems Marine epoxy. It's shelf and hold life are slightly less than AcraGlas, but otherwise the two are near equals.

If you intend to be a knifemaker for very long, it's in your best interest to use the best materials possible for the given job, including adhesives. If you cut corners on adhesives, you'll have people hunting you down in 5-7 years with issues for you to repair. It won't matter if you used the best steels and/or handle materials...all the individual will care about is that the knife you gave or sold them is falling apart.
 
Acraglass is all I use now after I read the glue wars thread.I do a lot of hidden tangs and I like that it only shrinks 1/10 of 1%.I've also used it on plenty of slab handles and I trust it more than anything else.
 
I use West system 3marine and as Ed said cheap epoxy will cost you in the long run.
Stan
 
Another vote for Acraglas. I just used it this afternoon :). It had been on the shelf for a while and the resin was partially solidified. I gently warmed the container and mixed it up, and it was good to go. I love the stuff.

--nathan
 
In my experience the epoxy materials have much more resistance to water than Cyanoacrylate materials. They will also span wider gaps without losing strength. The slow cure epoxies are nice to work with when you are setting up clamps and trying to properly align the parts.
 
One thing about acraglas, it's mixed by volume, not weight. I use two small syringes. One for resing and one for the hardener. Mix 4 parts resin to 1 part hardener in a small cup, mix for several minutes, and you're good to go. I've found for a typical full tang with two corby bolts and liners, I use about 4cc of resing and 1cc of hardener. The black dye packets are also very nice with one or two drops doing the trick if you're using black liners.

--nathan
 
AcraGlas - please clarify - are you using it with or without the glass fibers ?

It's good stuff .I used it on my rifles I made in gunsmithing school almost 40 years ago and it's still going strong !
 
I once won a .22 rifle silhouette match and became the proud owner of a coffee cup with a picture of a turkey and Match Winner on it. 3-4 years ago I broke the loop handle off of the cup. Put it back on with super glue and it has made a weekly and sometimes twice weekly trip through the dishwasher. Lots of shock treatment with hot coffee and lots of soaking in hot water. Still holding strong. Maybe not the best for knives but hard to beat for coffee cup repair.
 
Ed has the right info for sure.

Use an epoxy with the slowest cure possible. I mainly use System Three T-88, which sets in 24 hours.It is a structural epoxy and has an unbelievably high strength ( most epoxies are not structural). The K&G (Knife supplier) 24 hour epoxy is also superb for knives ( because it is made for that purpose).

And, of course, the champ is Acraglass.

The worst thing to ever put a handle on with is CA. It is not made to do that.....and won't last.
Fill a crack in the wood....stabilize the ivory....seal the surface - Perfect for the job.
But, for bonding the scales to the tang....it will fail....guarenteed!

Last time I checked, most knife tangs and the scales weren't made from porous china, so comparing the bond on a coffee cup to making a knife handle is like comparing the ability of a Bandaid to stopping arterial bleeding.
 
check out www.smooth-on.com/
mold making & casting
industrial
scroll down to
smooth-on epoxy adhesives
check out MT13,PC-3

has anyone used any of these products?

i have not

i have 2 new friends that make knives
they are dental teachnishons and think smooth on is great
 
Just one more tidbit. I also ended up using the West System after trying several others. I started with their 105 system but an engineer at West recommended their G/Flex product for handles. I use this exclusively and am very happy with it. I only use CA as a filler, ever.
 
I live in Germany, so I buy my epoxy here.
The brand name is UHU
I don't know if it is unique for them or if it works in general, but they claim that a bond with there product can withstand 3000N per square cm (4351 psi)
if cured by 180C. (356F.)
Also curing time goes down from 24 hrs to 5 min if cured by that temperature.

I don't know if it works for any brand epoxy, I do know that epoxy doesn't cure at all if it is to cold.
 
Peter Milner said:
Just one more tidbit. I also ended up using the West System after trying several others. I started with their 105 system but an engineer at West recommended their G/Flex product for handles. I use this exclusively and am very happy with it. I only use CA as a filler, ever.
Click to expand...

I have been very dissatisfied with Gflex and G5 epoxies. niether one holds anywhere near as good as their old system 3 or acraglass.
 
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