Epoxying question for you "seasoned" pros.

John Wilson said:
It’s used to make boat hulls that will see a thousand times more stress and fatigue than any knife handle will ever experience. Fiberglass boats from the 60s (especially sailboats) still fill every marina in the developed world. And that’s 1960s resin when it was a new concept and nobody knew anything about it. I have cut holes in 1960s hulls that are every bit as solid as a brand new hull. Where you see hull problems are with air bubbles and poor bonding to core materials. (Most hulls are a sandwich.) But properly laid glass from 50 years ago is still bonded to wooden structural members like the day it was laid.

GFlex 650 is on a whole new level from that. It is a toughened epoxy that will actually flex under shock loads instead of fracturing. When I see sailboats rounding the capes in unimaginable weather I don’t lose sleep over my knife skinning a deer or chopping cucumbers. If I did worry I’d use corby bolts instead of pins and go back to sleep.

I’ve made mistakes on a couple handles where I got in a rush and put the liners on out of order. Of course I didn’t notice until the handle was cured and I had shaped it, which meant I had to take off the handle and redo it. Nothing I did would make the G-Flex let go. I boiled the knife. I froze the knife. Nothing. I realized I would have to destroy the handle so I decided to see what it would take. I drilled out the pins. I beat the handle with a hammer. I chucked the blade in a vise and grabbed the scales with my biggest channel-lock pliars and tried to break the scales off. All it did was chew up the wood.

I finally took the knife to the grinder. What I found was that the scales, liners, and tang were basically fused into a mono-block. I had to grind the tang back to bare metal because even the streaky remnants of the fiber liner couldn’t be scraped off.

Now, granted this was a newly handled knife. As to the epoxy breaking down over time, I refer back to boat hulls. Can epoxy break down? Yes it can. Most of the time it’s due to UV light damage to cheaper polyester resin. True epoxy is a different animal than polyester resin and the price reflects that difference. Are all epoxies the same? No. But a lot of the difference goes back to being a fast-cure versus a slow cure formula, too.

Boss made a key point. Surface prep is probably the biggest factor. You find that to be true in boatyards everywhere. Bad fiberglass jobs fail regardless of the type of resin. Epoxy bonds via chemical reaction. Residue, bad mix, too much squeeze out leaving the epoxy too thin- all of these things change the reaction.
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Thank you sir! I figured as much but figured there was no harm in asking
 
Chris623 said:
Sure am glad I asked the original question................I've learned a whole lot more than I expected to. You guys are great!
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This site and the people on it are first class. I’ve never been around a finer group of people. They know their stuff and are willing to share that knowledge.
 
Ed is right on. Acraglas is excellent epoxy. There are other excellent epoxies also but way more marginal ones. I tend to use Gflex myself but wouldn't hesitate to use Acraglas on any project.

EdCaffreyMS said:
ve been at this a long time, and have been a "tester" for a number of the available "epoxies", and frankly, after testing them in my shop, I wouldn't touch most of the popular brands with a 10 foot pole. Whenever I've been asked to "test" product(s), I tend to ask a lot of questions.....and if they can't give me a shelf life, and/or a hold life that meets or beats Acraglas.... I politely decline. If they can't offer me better performance than what I'm already using....what's the point?
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Since I just got back home yesterday afternoon this is the first I've seen this thread. As I've stated so many times in the past I've got most respect for Ed's knife making knowledge and experience. Ed's forgot more about knifemaking than I'll ever know! :) BUT - on epoxy he and I have been round 'n round several times on the life of epoxy. I'm not going by my own knowledge, but from the opinion of the folks who actually make the stuff.

Here's a thread where it's discussed in depth with me contacting two major epoxy companies (West Sys and Raka) and Andy of Bladebond about epoxy life. Neither of them seemed to have any idea of a limited life of epoxy - lasts a lifetime! 100 yrs+.

Rather than rehash the info here's the thread. My post is #4 https://knifedogs.com/threads/which-epoxy-do-you-use-and-why.40604/

Here is the thread for Raka and West Systems (my post is #6): https://knifedogs.com/threads/which-epoxy-do-you-use-and-why.40604/
 
Merle said:
WoundSeal Powder works really well. Has saved me a trip to Urgent Care at least once.
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How this for ironic?

After reading your comment about WoundSeal Powder, I thought it might be good to pick up some in case someone in my class happened to do more than just nick themselves. Then the other day, I was sharpening a Planer blade on a wheel and the edge caught on me. Flipped the blade around and before I lost it it took the tip of my thumb off........along with nail and some of the nail bed. Blood? Plenty of it. Opened my tool drawer and took out a tube of WoundSeal and wallah! "Worked a treat" as my Australian friend once said.

So thanks for the tip, Merle.
 
and then there is this bedding glass stuff that I would like to try but never can find it.
 
Chris623 said:
How this for ironic?

After reading your comment about WoundSeal Powder, I thought it might be good to pick up some in case someone in my class happened to do more than just nick themselves. Then the other day, I was sharpening a Planer blade on a wheel and the edge caught on me. Flipped the blade around and before I lost it it took the tip of my thumb off........along with nail and some of the nail bed. Blood? Plenty of it. Opened my tool drawer and took out a tube of WoundSeal and wallah! "Worked a treat" as my Australian friend once said.

So thanks for the tip, Merle.
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Ouch!!!
 
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