Question about epoxy...

stereo.pete

stereo.pete

Joined
Apr 7, 2013
Messages
600
Alright Folks,

I've googled for a definite answer and wasn't able to find what I was looking for. Here's the story so far...

I decided to have a go at making my own micarta using 3M Fiberglass Epoxy Resin and cut up khaki material. I mixed the epoxy and hardener and soaked each strip of material and layered it into my homemade press. After 18 hours the epoxy was still very much liquid, after 48 hours it seemed to be setting but very slowly. I clearly did not accurately mix the epoxy and hardner, nor did I put enough hardner into the mix.

Should I just toss the mess or will it cure eventually? I started this project last Wednesday and the strip of khaki is still somewhat flexible.

Thanks,

-Pete
 
Without seeing it, and based on what you've written, I'd say toss it. I've built three boats from scratch using the stuff and one knife handle for a Skyline using Bondo and Nomex. Each time the epoxy was hardened and workable in less than 24 hours. It shouldn't be "flexible".

Unless your canvas is irreplaceable, cut your losses and don't waste any more time waiting on this batch. Good luck,
James
 
vaisforloverss said:
Without seeing it, and based on what you've written, I'd say toss it. I've built three boats from scratch using the stuff and one knife handle for a Skyline using Bondo and Nomex. Each time the epoxy was hardened and workable in less than 24 hours. It shouldn't be "flexible".

Unless your canvas is irreplaceable, cut your losses and don't waste any more time waiting on this batch. Good luck,
James
Click to expand...

James,

Thanks, I had a sinking feeling that it would take a few months to cure if ever at all. I just needed someone to push me in the right direction and thank you for that. I just finished cutting a bunch of denim to try making blue jeans micarta, this time I will accurately measure the hardner.

P.S. I've heard good things about West Systems and I love their pump design, looks really simple. Does anyone have a good source online to buy from?

Thanks,

-Pete
 
Pete-

I used West Systems fast hardening clear epoxy on the two canoes I built. It is truely Marine grade. I got mine from West marine. It is expensive in small knife size quantities but good stuff. I would have liked to use it on my knife handle. As my boatbuilding days are over I picked up some far less expensive Bondo epoxy and had no issues with it on my Skyline handles. With your recent experience, you've already learned it is important to have the correct epoxy/hardener ratio.

http://www.bladeforums.com/forums/s...-Attempt-at-home-made-scales!?highlight=Nomex

Good luck
James
 
if you have not already tossed the khaki batch, try heating it to speed the cure.
no guarantee it'll work, but you might get lucky and it'll take minimal effort.
just wrap your bundle of uncured mycarts in freezer paper and put the bundle in a black trash bag -- then set that out in the sun for a day.
if the extra heat is going to do it, 6 hours of direct sunlight should be enough time.
 
When I first started glass bedding rifles, I had occasional problems getting the epoxy to harden completely. This is Acra-Glas from Brownells. Finally I bit the bullet and read the directions. After I started getting the proportions correct and adequitely mixing them, problems ended. For the longer setting epoxy (24 hour) Brownells recommends 2-3 minutes of constant stirring. Proprtions are very important, as too much or too little hardener will result in poor hardening. I have some Acra-Glas that is over 5 years old that sets as hard as glass if I use it correctly. I use it an all my fixed blade knives. Two of them are used in my kitchen daily for the past 3 years and have no pins, just epoxy (this is an ongoing test).
Chip Kunkle
 
One thing I´ve learned is that epoxy won´t cure in the cold.
That might be your issue
 
Since you're in Chicago, go down to a chandlery and pick up some west systems 105 resin and 205 or 207 hardener. Even with the pumps, you should still weigh them to assure your ratio is correct. An easy way is to build a balance beam with the fulcrum at the right ratio. Mix for 1 minute, then pour it into a clean cup and mix for another 1-2 minutes. Two mixing cups ensures no pockets of resin or hardener being trapped in the bottom and causing issues later on when you cut the block.

Spread the epoxy out on a piece of wax paper before doing your lay up, this will dissipate th heat and slow th flash time down. It will also reduce the very real risk of combustion. When doing laminations, I only soak every other piece, I let the previous one soak through to th next, reducing the amount of epoxy waste. A cheap chip brush and a hard ridged roller are good for this.


-Xander
 
Ok, so I finally pulled the plug on this project, here are the results of the first failed "mycarta" batch.

Here's the sheet right out of the press...
badcarta2.jpg
.
The sheet was tacky on the exterior and very flexible bending to 45 degrees.

I cut off a small chunk to try sanding on with my Dremel and layers would peel away from time to time, so clearly it would not make a good medium for sculpting a handle.
badcarta.jpg



Granted I failed but I will say that I learned a lot and will change quite a few aspects of the process in the future.
 
If you aren't going to use West Systems, be sure to pick up a laminating epoxy. It will have the properties needed for such work, gives you some options to shop around. I have seen some very good quality reains labeled as house brands for cheaper than west systems.


-X
 
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