Laminating G-10 to Maple: what went wrong?

Rotte

Rotte

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Aug 30, 2008
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Thanks in advance.

This is my first attempt to make a handle for a knife using G-10 liners under Maple scales. (BTW, I'm an amateur hobbyist and this is my 3rd or 4th handle.)



As you can see I got no adhesion with the G-10, and the liners just pulled off the scales.

Here's what I did:

-- cleaned the Maple and G-10 with rubbing alcohol.
-- lightly sanded both G-10 and Maple surfaces with 100 grit sandpaper
-- re-cleaned both G-10 and Maple surfaces with rubbing alcohol (70% Ethanol, 30% water)
-- wiped surfaces dry and allowed to dry for a few minutes
-- mixed up my epoxy and applied to wood in a thin layer
-- laid G-10 liners on and worked 'em 'into' the wood
-- clamped liners to scales with Pony clamp
-- let sit at 61º overnight (18 hours)

What I see:

-- wood is well covered with epoxy in thin even layer of epoxy. There is even a slight impression of the light texture of the G-10 in the surface of the epoxy/wood.
-- there appears to be no epoxy adherent to the G-10
-- there is even and uniform (relatively) squeeze-out of epoxy along the edge of the wood.
-- epoxy is dried and very hard (a dried drop on the edge deforms slightly when struck with the back of a knife).

This is my first time working with G-10 and I just assumed that epoxy would stick to it like....glue. :o Where'd I go wrong?
 
I'm guessing that you clamped it too tight and the epoxy was all squeezed out of the joint. Try using less clamp pressure and try using a different epoxy. I've heard many stories of devcon epoxy failing in knife making applications.
 
I don't think the devcon would fail that quickly, or totally if nothing else was wrong. What is the story on the maple scales?
 
If there's no epoxy on the g10 then you didn't prepare the g10 well enough. Next time scuff it up more until there's absolutely no shiny surface left at all. It takes a lot of work to properly prepare g10 for epoxy.
 
kdogmcg said:
What is the story on the maple scales?
Click to expand...

Thanks guys.

The clamps are just spring clamps (pictured above), but do have some pretty good squeeze. I used two per glue up and distibuted the pressure by laying a flat piece of steel across the G-10 so I wouldn't have specific pressure points. The residual layer of epoxy on the wood is very, very thin. Perhaps too much epoxy got squeezed out.

The maple scales are from a piece of maple I have had lying around for 10 years. Well dried. No finish. I sanded the maple with the same 100 grit paper. The epoxy does appear to have bonded nicely with the wood. The fail is with the expoy/G-10 bond. I just gave the G-10 a light sanding. Perhaps I needed to scuff the surface better.

-- Would acetone be a better cleansing agent after sanding?

-- Is there a better epoxy to use? (And I'm sure there is...)
 
All of the epoxy appears to be on the wood, none on the G-10 so the G-10 wasn't prepped correctly. I'd hit the G-10 HARD with 80 grit and take every last bit of shine off. Good an fuzzy to give the epoxy a place to grab. If you can see a definite layer of epoxy on the maple, then clamping pressure was fine.
 
Trace the tang on to the g10. Drill a few small holes though the g10 and slightly into the wood. This will allow the epoxy to bridge the wood and g10. Also leave both surfaces at 60 grit or so. The devcon is not the best but has worked for many a knife maker. G flex is a better choice but that wasn't your problem.
 
A lot of guys are now using denatured alcohol instead of rubbing alcohol or acetone
 
Spring clamps won't exert enough pressure to squeeze out epoxy. I've done lots of glue ups in my wood shop and there's no way spring clamps could squeeze the epoxy out.

Actually I'm of the opinion that it isn't possible to squeeze glue out with any clamp and that other problems cause glue joint failure. I've tried to force glue joint failure by applying WAY LOTS TOO MUCH clamp pressure, enough pressure to begin crushing the wood I was using for testing, and my glue joint wouldn't fail.

The others are more likely correct. Take a look at surface prep.
 
Thank you!

In my experience with gluing other stuff--high clamp pressure tends to be better than little or no pressure. But this G-10 is new stuff for me. :foot:
 
If you have a film of glue on the wood the pressure shouldn't have been to much imho.
I use acetone and "rinse" with pure alchool or isopropilic alchool (if i have it). I create some undercuts with a tiny rotary burr in addition to sanding at 60/80g (depending on what i have on the granite at the moment).
I don't like to glue the glazed side of g10
 
61 degrees is too cool, you should bring it inside somewhere over 70, that you were able to dent it at all probably means it hadn't fully set up

You should have almost all sign of gloss sanded from the G10

Devcon and other consumer grade epoxy suck. They let go over time.

It may be past its shelf date. Adhesion quality is one of the first properties to go. Just because an epoxy sets up doesn't mean it will stick well. Everyone should test their epoxy first before using it on a knife to look for this problem.

Epoxy needs to be mixed way more than most people realize. Poor mixed epoxy doesn't develop full strength or good adhesion.

I used acetone for years before I learned high zoot alcohol was better and never had any problems with it. it's not ideal but it's not that bad. I use a screw driver to rub epoxy onto both surfaces being bonded which might reduce effects from contamination on the surface.

That it pulled away from the G10 and not the wood could be a red herring. If it's weak from being past its shelf date, poor quality to begin with, and/or mixed improperly, it's going to pull away from something, and the non-porous side will usually loose.

I think you should get yourself some better epoxy, make sure to mix it very very well, do your surface prep and let it cure in a warmer environment.
 
Also remember that "straight" epoxy, which is to say just resin and harder, may not beoptimuml as an adhesive. You might want a little bit of filler. The late John
White turned my on to using colloidal silica. Some of the stuff like G-Flex may already have filler added. IIRC, it is marketed to boat people as an adhesive to hold stuff together while you laminate/lay stuff up.
 
I'll say it too- my epoxy guy says that almost all acetone is recycled these days and leaves a film, which you can avoid by using high strength alcohol (as Nathan points out.)
I don't know how big an issue that residue would be if you used a high strength, flexible epoxy such as G-flex which is somewhat forgiving on oily woods.
 
Nathan the Machinist said:
61 degrees is too cool, you should bring it inside somewhere over 70, that you were able to dent it at all probably means it hadn't fully set up.
Click to expand...

Nathan, 61 degrees is the inside temperature! The garage was much cooler, probably 40's. It's acting winter-like here already. Iwas happy my wife let me use the epoxy in the kitchen!

Can you guys recommend a source for better epoxy? All I find on the shelves around here is Devcon, Loctite, and DoItBest; they all look the same.
 
Judging by your location, I guess a west marine is not nearby. You can order gflex from west marine on line. I just picked up some slow setting locktite epoxy at a Menard's, but I was on travel. They don't carry it here. Also check local hobby shops, some carry the good stuff.
 
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