Micarta Scales Warping?

B

Bamph

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Aug 9, 2015
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Most of the knives I make are fixed blades with Micarta scales and G10 liners. Sometimes, the scales will take a warp or bend when glued up. I'm using medium CA glue and usually mist with Zip Kicker.

This happens when I'm gluing up the scales, before they go on the knife. It doesn't happen every time, and sometimes a set of scales will warp and other times the same material won't.

Has anyone else seen this? Any suggestions?
 
Maybe it's the heat of grinding that's making things warp? Dunno, I've never had much problems with micarta...
 
Sounds strange but clamping both liner and scale to something flat while the glue sets should help.
I always put a sheath of baking paper inbetween so it doesn't stick to the plank I use.
 
where are you buying the micarta? are you sure its genuine. no i have never seen that happen. are the scales full thickness when they are applied? 1/4" , 3/8"?
 
Micarta bends more easily than some other materials. It could be in how you are storing or handling it.
 
Thanks for the tips. I think it might be the the heat. The Zip Kicker does make it hot, but also sometimes I'm not careful when I do the rough grinding when I'm shaping the scales.

Ben
 
Bamph said:
Thanks for the tips. I think it might be the the heat. The Zip Kicker does make it hot, but also sometimes I'm not careful when I do the rough grinding when I'm shaping the scales.

Ben
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Are you making sure the scales are flat on a granite surface plate with sandpaper before glueing liners on? It comes relatively flat but not perfect so that could be part of the issue if you aren’t flattening the scales to begin with. Also making sure it’s professional micarta versus homemade can make a difference depending on the type of resin used in the process of making the material.
 
Yes, I’ve had this happen a few times. Professionally made micarta, clamped to a surface plate for glue up to g10 liners. The longer the scales the worse it can tend to be. Also had it happen with wood and g10 liners. Always with CA glue. Everything dead flat to start.

I’m thinking it has something to do with the the heat as well, but it’s hit or miss and by the time I cut the scales out of the bowed slabs and get them back on the surface plate prior to final glue up, it’s usually a non issue.
 
I think it's got to do with the shrink of the adhesive and the difference in the amount of surface area each substrate exposes to the glue joint. It has a bimetal spring effect. It seems to always curl away from the G10 side. CA that I've used shrinks a lot. I have no warping/curling issues using epoxy on Micarta and G10.
 
Yeah it happens... Happens REALLY bad with g-carta (at least, the Mexican blanket stuff) with any bit of heat whatsoever.

If you run into the issue again you can actually use a heat gun and warm it up good and take the bow out. It's a little more complicated if it has liners though, because you risk loosening the bond between the two.
 
if you take the bow out with a heat gun, doesnt it just come back when it cools? the bimetal effect is an interesting point. i wonder what gcarta uses for a resin? i only used it once, it seemed more dense and harder to sand than micarta.
 
The resin in G-10 and similar laminates is a heat curing epoxy. The laminate is glass fiber.
Micarta uses phenolic resin.
 
john april said:
if you take the bow out with a heat gun, doesnt it just come back when it cools? the bimetal effect is an interesting point. i wonder what gcarta uses for a resin? i only used it once, it seemed more dense and harder to sand than micarta.
Click to expand...
IIRC, I think it's polyester. I believe he said it in an interview.

Also, I should point out that I didn't come up with that "bimetallic spring" effect on my own. It's just my summarization of what I've gleaned from googling the topic.
 
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