Epoxy

I like your idea with the straws. Makes sense. I had to fill some checks (cracks)in the wood on a slab table I made. Just wound up using the slow cure hardener and letting it slowly work its way down and slowly adding more. Took forever. I had syringes, but never thought of straws on the end. I could have gotten into much thinner cracks by squishing the end on a straw.

Okay, So g flex hardener....or is there g flex resin too? Different stuff than 105 resin and 205 or206 hardener? Do people use 105/205/206 for knife handles too?

Justin, I am just figuring I have about 2 litres of West system 105 resin and if that is something that people use for blades I have about $60 worth of it on hand already!

Randy
 
As best as I can tell, G-Flex is "premixed" 105, whatever hardener it uses and filler material. If you want to use your 105, go grab a canister of colloidal silica, micro balloons or some similar filler as it makes the mix a better straight adhesive. The late John White turns me onto the silica.
Randydb said:
I like your idea with the straws. Makes sense. I had to fill some checks (cracks)in the wood on a slab table I made. Just wound up using the slow cure hardener and letting it slowly work its way down and slowly adding more. Took forever. I had syringes, but never thought of straws on the end. I could have gotten into much thinner cracks by squishing the end on a straw.

Okay, So g flex hardener....or is there g flex resin too? Different stuff than 105 resin and 205 or206 hardener? Do people use 105/205/206 for knife handles too?

Justin, I am just figuring I have about 2 litres of West system 105 resin and if that is something that people use for blades I have about $60 worth of it on hand already!

Randy
Click to expand...
 
G-Flex is a completely different resin than 105/205/206 and it has it's own hardener. It was designed to glue, among other things, some plastics used to make kayaks. Don't try to mix G-Flex resin with 205/206 hardener - you will probably blow the roof off your shop. Just kidding.

G-Flex is the better epoxy for gluing scales to full tangs because it has a small amount of flexibility. When the tang and scales expand or contract at different rates due to temperature changes, the G-Flex will not break loose.

Tim
 
I will have to head over to the place where I get my West system epoxy from and get some colloidal silica. I see West systems makes that too. I'm sure the shop carries it.

I checked on amazon for the g flex and it is pretty expensive... $50 for the 4 oz bottles of it. Hopefully the colloidal silica is cheaper!
 
A cardboard can of that silica will last you forever.
Randydb said:
I will have to head over to the place where I get my West system epoxy from and get some colloidal silica. I see West systems makes that too. I'm sure the shop carries it.

I checked on amazon for the g flex and it is pretty expensive... $50 for the 4 oz bottles of it. Hopefully the colloidal silica is cheaper!
Click to expand...
 
What I have heard is that G-Flex was originally designed to be a "temporary" adhesive to hold things together until you got them laid up, filleted, etc with the regular West stuff. I may be wrong,
tim37a said:
G-Flex is a completely different resin than 105/205/206 and it has it's own hardener. It was designed to glue, among other things, some plastics used to make kayaks. Don't try to mix G-Flex resin with 205/206 hardener - you will probably blow the roof off your shop. Just kidding.

G-Flex is the better epoxy for gluing scales to full tangs because it has a small amount of flexibility. When the tang and scales expand or contract at different rates due to temperature changes, the G-Flex will not break loose.

Tim
Click to expand...
 
When I read on West Systems site it looks like g flex is its own adhesive that is made to have a very strong bond.
http://www.westsystem.com/ss/west-system-launches-g-flex-epoxy/

The 105 system has a page of fillers to add to 105 to use it as an adhesive. It looks like their colloidal silica (406) and high density filler (404) offer the best bonding strengths for the 105 system.
http://www.westsystem.com/ss/filler-selection-guide/

I can't find any comparison of g flex strength to 406 or 404 strength.

One advantage of the gflex is that it is 1:1 so their isn't much in the way of measuring needed. It looks to me like the fillers might be "off white" in color too...I will talk to the dealer in the next day or so.
 
Another interesting thing I read was that g flex will even bond to wood that is wet!
 
Some of the "premixed" epoxy is white, which, in my limited experience with the stuff is worse that the pale yellowish red you get with the regular stuff. It shows really badly. When you add the silica, it just gets kind of cloudy. I add it to the resin because ti takes awhile to mix it up and then add the hardener. You don't need the "peanut butter" or even the "mayonnaise" consistency like you do for filleting. Just thicken it up a tad. Usually a few nice blobs on the end of a Starbucks swizzle stick works for me. Be careful as that slice likes you fly around when you open the can. Our uses for epoxy are so limited compared to boat builders, so we have things pretty easy.
 
I use G Flex. You can buy it at marine stores like West Marine.
 
I started using G-Flex after I watched a YouTube video of a guy who glued up a knife without pins, then proceeded to beat the handle with a hammer. He finally broke the scales off, but the wood was still glued to the metal; as in, the metal/wood bond did not fail. It was impressive. I looked for the video, but unfortunately LG makes a smartphone called the flex and there seem to be thousands of videos of it cluttering up youtube. I did find another video with G-10 glued to one side and left proud so he could get leverage to beat the scale off. He finally got it to fail, but his conclusion was that it was good and he liked it.

Yes, you can glue up wet scales. G-Flex will set and cure underwater. I'm sure that's a big plus for marine applications, but not quite sure that it would be relevant to knifemakers. West Systems promotes it as an epoxy designed for hard to bond materials. For me...metal and micarta, g-10 or wood. I've read that you can markedly increase the bond strength if you will sand the g-flex into the metal. Don't know if it's true, but I do this. I've never had it fail me.
 
I've used G-Flex, but don't like the runny consistency.

I have a top secret weapon I use for handles that will possibly see extreme abuse, but it's an aerospace adhesive not readily available, has a VERY short shelf life, and is painfully expensive. In my never-ending search for an alternative to this stuff, I've been testing a variety of products. BladeBond has shown promise with their Ultra epoxy as a replacement for G-Flex, for me (MUCH thicker consistency, and comparable strength), but my discussions with the owner of the company have him hinting at a possible new product that's even stronger. It'll be more expensive, of course, but compared to my top secret stuff it's dead cheap - less than twenty-five percent of the cost, in fact. If this stuff even manages to approach the results of the secret weapon, it will be my official replacement, I hope.


All of this is overkill, though. The fact is just about ANY quality epoxy, mixed correctly and used within its shelf life, WITH PROPER SURFACE PREPARATION, will work more than adequately for a knifemaker's purpose. Just like most makers, though, I tend to overthink stuff. :)
 
As Matt says - proper surface prep is the real key to epoxy bonding. Bladebond is got the edge a bit on all the epoxies mentioned per the datasheets - except perhaps for Matt's "secret weapon" he mentions. I like Bladebond!!!

I've been using Raka epoxies for years on boat work. They work just as good (or better?) than West systems and a good bit less expensive. On my last boat project (a stitch 'n glue) I ordered a 10 lb bag of colloidal silica and still got a 5 gal bucket of the stuff left - a life time supply...... even if I was only 30 yr old:)

Bladebond was developed for knife makers by a knife maker so you know it's good stuff. He's now got some good coloring agents for the epoxy also.

Ken H>
 
I alerted Andy, owner of BladeBond, that I'd mentioned a possible new product release for him (I wasn't sure whether I was supposed to be keeping it secret, so I carefully backtracked and apologized in advance for being a dumbass:D), and he asked me to post this while he's wrestling with his forum subscription:

Hi Matt,
Thanks for sending me the link on the bladeforum site
regarding the differences in epoxy strength between quick cure and
slow cure formulas. It's an interesting question that actually has a
pretty easy answer. There are three common types of epoxy formulations
that most of us have access to, and that we are all familiar with;
Mercaptan, Polyamid, and Amine. All three have advantages and
disadvantages, and application in which they excel the best. The
Mercaptan based quick cure formulas that we see most often at the big
box stores such as Loctite and Devcon are GREAT, when speed is needed.
They offer good physical properties in terms of shear strength and
adhesion, but where they are lacking the most is that they are NOT
waterproof. Mercaptan based epoxies are merely water resistant, but
under prolonged exposure to moisture will begin to soften. Ours is
better than the other brands on the market in this respect, as it is a
mercaptan hybrid, but will still soften if say, was submersed in a
lake for a couple of days. The amine based epoxies are waterproof, but
are generally a much thinner viscosity, and thus used for laminating
applications such as in boat building where one needs to "wet out"
fiberglass or carbon fiber cloth. They can and will work as adhesives,
but don't provide the optimum film thickness for maximum strength and
adhesion in a full tnag application. West 105 and I believe Acraglass
fall into this category. This is the reason why so many of you have
had problems with Acraglas in a full tang application, but not in a
hidden tang application...because the film thickness in the hidden
tang is much greater, and the epoxy is able to form adequate physical
properties. As an aside, I took a look at the Acraglas MSDS, and it
appears that Acraglas is some kind of phenolic modified epoxy...VERY
old technology. The last type of epoxy are the Polyamid based
formulas, and for our purposes these are the types we are most
interested in. Polyamids as an artifact of the chemistry give us the
best adhesion, and physical properties out of the three I have
outlined. BladeBond Ultra falls into this category, as does West
G-Flex, and many others. The polyamids are waterproof, and when
formulated correctly offer outstanding shear strength, flexural
strength and compressive yield. The drawbacks to Polyamids (not really
drawbacks...just artifacts of the chemistry), is that they are usually
pretty thick, and they cure VEEERRRYYYYY slow. But, if you want the
robust physical properties to hold scale to tang, this is the
chemistry you want. Of course the cure cycle can always be accelerated
with mild heat, so for me, this isn't really much of an issue. In
Texas we just put our knives in the trunk of our car in the summer,
and the epoxy cures in 2 hours instead overnight...LOL. You can
actually cut down on cure time a lot by simply microwaving the resin
and hardener for about 10 seconds in the microwave. This will cause
the mixed epoxy to tack up much quicker.
So I know the next question is "How do I know what kind I have?",
Well the easiest way to tell is to smell the hardener. Mercaptan based
hardeners, are generally very clear to light pale yellow, and they
smell HORRIBLE....like a mix of sulfur and rotten eggs. Polyamid
based hardeners are generally much darker in color, and have more of
an ammonia smell to them. As has already been referenced, surface prep
has to be correct for the epoxy to reach its maximum potential, but
that is a discussion for another post.

I have not posted these numbers before, but you're welcome to do so if
you think it would be of benefit to the guys on the forum.

BladeBond Ultra:

Mixed Viscosity: 9500cps
Tensile Strength: 6500psi
Tensile Elongation: 7%
Flexural Strength: 11,000psi
Flexural Modulus: 360,000psi
Compressive Yield: 12,000psi
Maximum Service Temperature: 170 degrees Fahrenheit


Regarding the new "super" formula you referred to, it looks like were
going to call it BladeBond Extreme. Its very similar in its working
properties to the Ultra formula, but it has incredible peel strength
and service temperature range (-55F- +240). Traditionally consumer
grade epoxies don't offer these two attributes, because they require
some pretty exotic raw materials, and a talented chemist with the know
how to put it together. In all honesty I was pretty intent on NOT
releasing this formula, simply because I didn't think the market would
accept the price. But judging from the feedback from the makers who
have actually tested it, the response was overwhelmingly positive, and
nobody seemed to be concerned about the price at all. A couple of the
makers that were on the Forged in Fire series are using it as we
speak, and say they will never use anything else, so it looks like
were going to shoot for a release around February. The Ultra formula
retails for $14.00 for a 4oz. kit, and it looks like the Extreme
formula will MSRP for about $22.00 for a 4oz. kit. It sounds like a
pretty vast difference, but when you break this down on a per
application basis, it's like .25 cents more per knife...not much to be
concerned about.

Anyway, if the board members have any further questions, they can
contact me directly via email at andy@bladebond.com

I am trying to register on the forum so I can post here, but am having
some trouble getting my account verified. I'd also look at purchasing
a sponsorship on this board as well. When I started BladeBond, one of
the main reasons was so that the knifemakers had access to a product
whose owner actually put something back into the knife making
industry...something WEST and Acraglas will never do.

Best Regards,

Andy Dear
Axis Outdoor Products
www.bladebond.com
 
I have been using Loctite 60 minute and I like it. Slow curing and is touted as having good resistance to cracking. it doesn't cure rock hard and has just a bit of give when you poke it with a sharp knife. I think this lends to it's resistance to cracking. It is water resistant, but not waterproof, but that's not an issue for me. It is translucent yellow and readily available. I think it is an Amine type, but I don't find it to be any more runny than any other epoxy i have used.
 
The post above is the type of response I've always got from Andy when asking questions about epoxy. Very detailed and full of info. I just wish every epoxy manuf was as open as Andy about providing good info and a MSDS on his product. Bladebond is GOOD stuff.

Ken H>
 
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