A new resin for lutherie?

[sebastiaan56]

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Thread started on: "Tue Apr 06, 2010 "


I just found this product http://www.ecopoxysystems.com/index.html

It is approved for food use and could well be the answer to the well documented allergy problems with epoxy. I think I might buy a small bottle and find out.

This bloke thinks its alright, http://toolmakingart.com/ Here are some more test results http://braoa.org/forum/coating-case-stu ... ffngefgt82

[Nick]

Cheers Sebastiaan, let us know how you get on with the stuff. Sounds like it could be a go as a pore filler.

[kiwigeo]

Seb,

We need photos taken before and after you drink the bottle of ecoepoxy.

[Dennis Leahy]

Thanks, Sebastiaan!

I think I'll get their sample kit and check it out.

Dennis

[Dennis Leahy]

OK, I found the thread again. Ecopoxy, Eco-poxy, peanut, soybean...

There, take that ANZLF search engine!

So, I did get some of their epoxy, but did not get any of their "clear coat" material (that will have to be another post.)

I did not drink any, but I sniffed it more than a seat-sniffing politician. It really has almost no smell at all - the hardener has an extremely mild smell and the resin, well, sniffing the freshly opened resin was like sniffing a clean plastic drinking cup. Obviously, the human nose cannot detect all dangerous chemicals (think carbon monoxide), but the Ecopoxy gives off probably less smell than Titebond glue, and is obviously in a completely different realm than any epoxy I have ever used in terms of noxious smell.

Hardener: The stuff is more yellow than amber. Fairly strong color, and I was pretty sure when I saw the hardener that this was not going to create a water-clear epoxy when mixed with the resin.

Resin: translucent but not transparent. Slightly cloudy white color.

Mixed at ratios between 2:1 and 4:1 (resin to hardener), all my thick samples are transparent yellow-amber, still more yellow than amber. I made up samples at those various ratios, and created thick samples (at least 12mm in the bottom of a plastic mixing cup), thin samples (a dollop was placed between waxed paper and squeezed to create a relatively thin film), smeared samples of each on Holly (supposedly the whitest wood in the world) and Claro Walnut to see about using it as a pore filler.

In no case could this be used as an initial clear coat to 'pop' the grain of a lighter shade of wood, unless you have a wood that you wish to shift the color towards the yellow part of the spectrum. This is not something you would use on Holly (bindings or purflings) as it looks more like yellow food coloring than some old-world amber color. I think it would look equally bad on Maple. But, it looked fine on Claro Walnut.

Again, this may not even be a real negative aspect of this epoxy, but I was checking to see if a single product could be used for two purposes (structural adhesive, and clear coat pore filler.)

I'll take pictures of my results and post it here.

As for the structural strength, I was told by John at Ecopoxy that the material could be mixed at various mixing ratios, yielding different working times and (one of my criteria) how hard the epoxy cures. I told John that for one of my uses, I wanted an epoxy that was close to brittle and wondered if that could be achieved using their resin and hardener. John tried 1:1, 2:1, 3:1, 4:1, 5:1 and 6:1 in his in-house testing, and 1:1 and 6:1 did not work at all.

Still I was skeptical of his results, because I had not worked with any epoxy that has that degree of latitude in mixing ratio. My tests confirmed that 2:1 , 3:1, and 4:1 all produce a hard and strong epoxy. I knew my tests would be very unscientific, but it became even more obvious to me as I attempted. In the "thin film" test, I had no way to get a truly consistent thickness of film, nor to ensure that the films from each blob were all the same thickness. In a 'fingernail test' (pushing down hard with a thumbnail, trying to make a dent), I could not make a mark on the thin film samples nor the thick samples. This was quite surprising, as I was sure with such a variety of mixing ratios, it would be easy to tell differences in hardness. I have mixed other epoxies that never cured properly, and other epoxies that seemed to cure properly but could still be dented with a fingernail. Ecopoxy is tough and forgiving in mixing ratio.

The mixing ratio did make a big difference in the time to initial kick (working time), and of course, I didn't even think of timing the tests as I was too busy smearing and clamping and labeling. I'd guess the 2:1 ratio mix was like a 5-minute epoxy, the 3:1 mix was like a 15-minute epoxy, and the 4:1 had at least 30 minutes of open time.

I did take some wood scraps, all from the same stick of wood, and glued them to the same board - with the intent of getting at least a general impression of the strength of the epoxy at the different mixing ratios. This was a waste of time, because having only one representative sample of each mixing ratio for a strength test didn't even give a hint of confidence in how well I had prepared the surfaces or performed the clamping. Even with this stupid test, snapping the sticks off the board showed that the wood failed before the epoxy - in every case.

I had misunderstood the Ecopoxy site verbiage, and thought that a single product was able to be used as a clear coat (using a 2:1 ratio) or as a structural epoxy (using a 4:1 ratio), but now know that I need to get some of their "clear coat" to re-test the material as a pore-filler and clear grain popping first coat.

Dennis

[Kim]

Thank you Dennis, you efforts to find a safer solution coupled with your willingness to share what you find with the rest of us are very much appreciated.

Cheers

Kim

[Dennis Leahy]

Kim wrote:

Thank you Dennis, you efforts to find a safer solution coupled with your willingness to share what you find with the rest of us are very much appreciated.

Cheers

Kim

Hey, my friend, we're all in this together!

Here are some images of the Ecopoxy.


The hardner (left) and resin (right)



Ecopoxy: Color at various mix ratios

Top: white printer paper with the hardened Ecopoxy as removed from the little mixing cups. Popsicle stirring sticks.
Beneath each hardened solid chunk is the thin-film sample, overlaying the paper/ink, and a poplar board, and sticking over the edge.
"Lemon Yellow" crayon as a color comparison.
Middle: Holly veneer with a smear of each mix ratio
Bottom: Claro Walnut (sanded to 80 grit) with a smear of each mix ratio




Claro Walnut guitar back cutoff, closeup showing 3:1 mix ratio smear of Ecopoxy

Note that in no case was the material properly prepped (sanded smooth to 220 grit) as a prepared instrument would be. Also, the smear of epoxy on each wood sample was done with the stirring stick, so in every case, this is thicker than any surface coating that would likely ever be used, and the surface is somewhere between self-leveled and moon cratered.

Note also that this is a bird's eye view, so when you are looking at the three solid samples, they get thicker as you go to the right, so you are looking through greater and greater depth of epoxy. There is the illusion that the material is darker as you go left to right, but in fact they actually get lighter as more resin is added. I realize now that I should have made all of the solid samples the same thickness, and that would have been easier to see the color differences. The color difference in the various mix ratios is more apparent in the smears on the Holly veneer.

My color conclusion (as a pore-filler/surface "popper") would be to test a small amount on a scrap of any medium-toned to darker wood species, and this may be fine as a surface coating. If too yellow for your taste, I could see adding a half drop of red, or orange, or brown to the epoxy to get something more toward amber or sienna or even sunset red-orange rather than the straight yellow of the plain Ecopoxy. I personally would not like this on Spruce, Maple, Holly... and would not consider it unless I tinted it to a warmer color. To my eye, this is the yellowest epoxy I have ever seen, but surprisingly, even with that much yellow cast, the Claro Walnut looked good in sunlight, incandescent, and fluorescent light. As a structural glue: Looking at the thin film sample, I would not hesitate to use this epoxy where an extremely thin line of glue would be displayed (such as when a fingerboard is epoxied to a neck.) It is certainly way way way too yellow to pour over a slab of wood as a bar top, for example, but when there's just a thin line, it is probably less yellow than Titebond (which is opaque pastel yellow.)

I'll go back to the folks at Ecopoxy and ask for a small sample of the clear coat, and will present that here as well (though it may realistically be a month or two before that happens.)

Hope this is helpful.

Dennis

[Lillian]

Thanks Dennis for the write up. They are time consuming, but for us, invaluable.

I must say though, the straight Ecopoxy makes the holly look like really old ivory.

[Dennis Leahy]

Lillian wrote:

Thanks Dennis for the write up. They are time consuming, but for us, invaluable.

I must say though, the straight Ecopoxy makes the holly look like really old ivory.

Glad it's of use, Lillian.

Well, talk about 'eye of the beholder' - what one sees as a detriment, another may see as a positive attribute. Thanks for your observation!

Dennis

[Lillian]

Um, well keep in mind that I'm viewing this on an older laptop. I might see something that no one else is seeing.

[sebastiaan56]

Thanks for this Dennis. I got in touch with them but they only wanted to deal with me in 5 gal pails and the mailing costs alone exceed my annual lutherie budget. Fair enuff, an unknown Aussie from their point of view.

Ive tried to get a few retailers interested but no one seems to fussed taking on an unknown product during the current slump.

I watch your results with great interest Dennis,

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