Epoxy - use of West Systems Filler

L

lonepine

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May 7, 2010
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Sooooooo... After three or four years of not making knives, I've begun again. I bit the bullet and got West System 105 resin and 206 hardener instead of hardware store epoxy. I was cheap and didn't get the pumps and now I wish i had done so. I was surprised at how runny it was but figured that's just the way it is. I used it to glue the handles onto three knives and tonight I found out that I was supposed to use their 406 colloidal silica filler to use it as a glue. Are the handles going to fall off the knives because I didn't use the filler?

- Paul Meske, Chippewa Falls, WI
 
Only if you squeezed it all out. The silica thickens it so it stays in place, but doesn't change adhesiveness.
 
I'm sure you'll be fine. I used the same epoxy for years with no failures. I would mix it 20-30 minutes early and let it thicken slightly before use. Last time, I bought the pre-thickened version in the tubes. It's great stuff.
 
There are lots of fillers used in epoxy work. I've used the silica, powdered graphite, powdered aluminum, sawdust & other stuff, depending on what you're making & how thick it needs to be for a joint. Flour or sawdust can wick moisture out of the air (think talc in Bondo), so just make sure you use something inert for blade scales. Main thing is to not press out all of the epoxy when gluing (called a "starved joint" in boat building) before it has a chance to set up.
 
If I want a darker tint, I mix wood ash from my fireplace in it. This results in a charcoal grey glue line, less conspicuous than clear, or solid colours.
 
Thanks for the good news! I had a little bit of a panic going on in my head over this. I don't clamp things super hard with epoxy so I should not have starved joints. It's seems sort of strange, neither of two knife making supply places I looked at that sell West Systems carry the colloidal silica filler, nor filler of any sort.

- Paul Meske, Chippewa Falls, WI
 
If they do they likely call it a thickener and not filter. If you'd really like some I believe I have some left over from other projects, and you're welcome to it if I can put my hands on it. I'm in Black River Falls.
 
Many knife makers have favorite spring clamps and other tools to hold their scales while epoxy sets up to keep from starving the joint and getting a poor bond. My method is probably not going to be very popular because it takes longer but I glue up one side at a time on a marble pastry board covered with wax paper. I put a can of soup on the scale and blade and let gravity hold it in place. You have to check back on it until the epoxy tacks up so the scale is still lined up and tight to the guard or bolsters but it is pretty simple to do. I have been doing this for the last 3 or 4 years and it produces strong bonds with no problems. I also like the G-flex in tubes which is a little thicker than their bottled formula. I glue liners on with 20 minute Loctite by the same method. I do this at night on my dining table so first thing in the morning I can do it again. I usually do a couple knives at a time and that speeds thing up. Light spring clamps would work just as well if you can find the right clamps. My opinion again. Larry




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You can get all of the West products from West Marine (no relation) I have been using West 105/205/206 pretty much from day one, but the late John White, who was a boat builder for much of his adult life, turned me on to the colloidal silica. I have made a number of smaller pinless hidden tang knives by notching the tang with a Dremel wheel and roughing up the inside of the tang slot to give a "mechanical" bond.
 
Just a comment, but the 105 series epoxy is a laminating resin. G-flex is a far better bonding resin for knives. The 105 is best for bonding fiber things like glass cloth, canvas and other cloth , and wood. It is designed to get its strength from the fibers in the bond, not from being strong itself. It will work fine on a knife, but isn't the best choice.

G-flen is a structural resin, which is made to bond solid things and be as strong as the other arts of the assembly.
 
wonderful!!! I thought I was taking a step forward and find I've made little or no progress (in regard to epoxy), but on the other hand I only have a ten year supply of 105 to use up. :-)

- Paul Meske, Chippewa Falls, WI
 
All is not lost. If you use the 105 with thickeners, do a proper surface prep with abrasives, rinse with acetone, MEK or denatured alcohol, then use a filler like cabosil & pin or screw the scales in place, I'm going to bet that the knife will outlast you and perhaps a couple more generations. People have used all kinds of epoxy for making knives & there are good, better & best ways of sticking the thing together. As long as your surface prep is done correctly & the epoxy has a chance to set up properly, there shouldn't be any issues.

Where people usually have trouble with epoxy is in the surface prep. They don't abrade the surface, or they don't clean & degrease the parts as they should, then the epoxy gets blamed for the bad joint instead of the way it was used. Any wax, oil or contaminate will affect the ability of the epoxy to make a bond. I'm still using the "hobby shop" slow set epoxy (30 minute) until it's used up & there aren't any problems with it so far.

For sure the West System G-Flex stuff is better in all regards than what I'm using, but I know if I do the surface prep as I should, I won't have trouble later on. I would never rely solely on epoxy to bond metal to wood or micarta, where there is the possibility of a lot of force & impact. In the same fashion, I wouldn't use a mechanical fastener by itself for the same reason. The combination of the two working together is about all that's needed for a good grip which is long lasting. If you rivet, pin or screw things together with an epoxy bedding compound & let the bond set up long enough, it should be there for good.

In the west system literature, the 105 is called "the basic ingredient of all West System epoxy compounds" so I'm going to guess that it's ok to use for a knife as long as it's used properly. Their data sheet says it can be used for coating, laminating & bonding to wood, composite materials & metals. Just my two cents worth.
 
My understanding is that G-Flex was initially designed as a temporary adhesive to hold things together why the limits set up.
 
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