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West system epoxy
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AndrewE
Posts: 56
Joined: Oct. 6 2004
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 RE: West system epoxy (in reply to JasonM)
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Just so I don't misquote what Aaron said here's he's reponse word for word;
" I have been using this method for the last 5 or 6 years now I think. It works quite well and is fairly easy once you get comfortable with it. The West system epoxy hardener that you want is the 207 (I think it starts with a 2) the longest setting one. YOu have to be very good about the mix ratio with this epoxy or else it won't cure right. You can get the calibrated pumps, but I have found them to be sometimes less than perfect. I use a digital scale. I think its a 3.5 ratio epoxy to hardener, but it will tell you on the container.
The procedure is pretty straight forward. You make up your plate with some flat laying plastic. Don't use it if it rolls up, it has to lay reasonably flat. You then sand the underside, the gluing surface of the plate, with 180 or 220. You want to score it up good, to give the epoxy something to hold onto. This also helps knock off any ridges or whatever on the edges where you have cut out the plate. Make sure the plate is clean and your guitar is clean and spread the epoxy on the plate. Put it down on the guitar and start working out the bubbles and excess epoxy. I use a small flat wooden block, about 1 1/2 or 2 inches square. Using nice and soft white paper towels clean up the epoxy, you will use a fair amount of towels. Make sure you have dripped over on the sides. Once you have it cleaned up to the point you only have a faint haze from the epoxy, use a little mineral spirits or naptha on a paper towel to get up the rest. I forget which one I use right now, I know it starts with a VPM, so I think it's naptha. The plate will take 24 hours to fully harden and you need to keep the guitar flat to keep the plate from sliding around.
Removal is easy, it will pull right off, although you will need to deal with removing the epoxy once you do. I just sand it back a bit and build up more french polish. The only time it gets tricky is when the plate has been worn down from constant golpes. Then you need to use some lighter fluid to help get it to release. Basically at that point the plate has been pounded into the top a bit and you can pull up finish or even a little wood if you don't. It still is much safer, easier and better for the guitar's sound than the self adhesive plates".
Aaron response about sound quality with self adhesive plates;
"I think they are less than good for the sound of the guitar as the adhesive does not ever dry. Therefore it remains a sticky goo between the top and the plate".
I just received a brochure on west system and yer it looks great for boats, on a guitar it still seems a bit scarey.
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REPORT THIS POST AS INAPPROPRIATE |
Date Sep. 5 2007 0:13:37
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n85ae
Posts: 877
Joined: Sep. 7 2006
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RE: West system epoxy (in reply to AndrewE)
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Andrew -
What you describe would work, I personally would definetly NOT do it though.
That's based on my experience using the stuff.
It cures clear if it is fairly thin, and is in fact used as a wood finish a lot for
boats when thinned. I used it as a floor finish in our camper trailer because
it is very durable, and I wanted a super tough finish on the floor.
West System's epoxy 105 is a much harder material than the guitar's finish
will ever be. So if it bonds, and you ever need to remove it, you will be taking
off guitar finish to do it. I'm not fooling either. Aaron's kidding himself, he
obviously has not removed a lot of tap plates bonded with this stuff. I have
sanded a lot of stuff made with this, and we're talking belt sander action.
You will find yourself cursing Aaron for twenty years if you ever have to try
to hand sand this stuff off your guitar. It is a major pain to hand sand in it's
pure form, less fillers.
It absolutely does not stick to plastic, you will have to sand the plastic very
well to get some tooth in it, and you may find yourself with a tap plate laying
on the floor after a golpe which knocks it free. Plastic is commonly used as a
molding and release material for this stuff.
It reminds me of reading about a plane where the guy laminated a layer
of polyester (i.e. plastic) into the wing of his plane, and it delaminated in
flight. Polyester is commonly used in composite building, and is called
peel-ply you use it as the top layer to absorb excess resin, then after
curing it simply pulls off taking the excess resin with it. Needless to say
the airplane guy is no longer playing guitar.
It is VERY messy, and the best cleaning agent is Alchohol, and MEK, which
needless to say aren't good choices for a guitar. Naptha works, but only
poorly. Same goes for mineral spirits. That's probably why he mentioned
the LOTS of paper towels.
The pumps work very well, and the biggest problem people have is you need
to pump some material through the pump to eliminate air bubbles in order to
get the ratio's correct.
I use the 105 Resin, and the 205 and 206 hardeners. I prefer the 206.
206 will start to thicken after an hour or so, and be at the "green"
stage in about 4-6 hours (this is where it is a bit soft, and can be cut
with a utility knife). After 24 hours it is like rock, and after a week
indestructable.
The 400 series fillers are very usefull for transforming the resin for
various use. Like as a sandable filler, or as a structural adhesive, or
even as a bearing surface using graphite filler.
Whatever you do if you use it, do not mix it in a cup, and then leave it
sitting there. Pour it out in a tray or some other flat surface. In a cup
it will exotherm, which is basically the epoxy getting hot as it cures, and
making itself cure faster, in turn making more heat. I have had it start
smoking, and had to take it outside the shop when this has happened.
When spread out thinly the heat dissapates, and exotherming won't
happen.
It's not at all scary stuff, it's just messy, messy, messy, until it cures then
it's tough like steel.
My very nice Pedro De Miguel appears to have an adhesive back tap plate,
same as my cheap Yamaha. Can't see why you wouldn't want to simply
just go that route??? Seems a lot simpler.
Regards,
Jeff
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REPORT THIS POST AS INAPPROPRIATE |
Date Sep. 5 2007 15:26:53
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aarongreen
Posts: 367
Joined: Jan. 16 2004
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RE: West system epoxy (in reply to AndrewE)
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Hi Jeff,
Interesting. I was first introduced to this method 12 years ago by Robert Ruck and Richard Brune. As you probably know are both renown luthiers with many, many years experience between them, they have tried it all and I know Richard still uses this method and I would bet Robert does too. Their tap plates were the most invisible I have ever encountered so I had to ask how they did it. At first I thought they were kidding me when they told me about using epoxy so I can understand your incredulousness. However my experience has shown me that this method is quite superior to every other approach to fixing a tap plate.
First of all, you can sand epoxy quite easily, when I used it for pore filler I did it all the time. In fact I stopped using it for pore filler as it didn't dry hard enough for my liking. A very thin flim is all you get when you attach a plate properly and it presents no issues when replacing the plate, just sand back slightly and add some more french polish (which is what I use anyways) and you're in business. This is not supposition on my part, I have done it 4 or 5 times now. Usually when the client comes back and requests a bigger plate or something along those lines.
You are quite correct that epoxy does not stick to plastic as well as other materials. This is why you sand the underside of the plate, as I told Andrew, and is also why you can remove the plate. However so far none have fallen off on their own accord and I have never heard of it happening to one of my guitars or any other luthiers who use this method. Elmers and hide glue, both common glues for tap plates do not stick to plastic very well either. The stresses an airplane wing endures is much different than what you put a tap plate through.
In my experience the West system does not leave much room for the mix ratio to be off. I do not recommend the pumps, I even have the new ones that they said were supposed to work better than the old ones.... they don't. You are also stuck with the amount the pumps are calibrated for and that is way more than you need for a tap plate. A digital scale is better.
Insofar as the exothermic nature of epoxy, the amount you mix up for this procedure is small enough that it should not get that hot. I have never had it start smoking on me, although I know when you mix large quantites that is a problem.
In regards to clean up, I use a fair amount of paper towels because I end up squeezing out most of the epoxy under the plate to get rid of air bubbles. I use a lot less now than I did when I first started using this method, so I thought I would pass along some advice for a first timer. The haze that is left is cleaned up with with the solvent I mentioned and only a tiny bit of it at that. The french polish won't be affected by the solvent if you keep it to a minimum and it has done a very nice job for me removing the final haze of the epoxy.
The best part of this method is it yields a plate that is as close to invisible as I have ever seen or not seen as the case may be. I never got such good results with the self adhesive variety, or using Elmers like Lester DeVoe did for many years, and from whom I learned that method. Andrew mentioned that Lester is using epoxy now too so perhaps there is something to it. If someone prefers self adhesive plates, thats great, however I won't be the one to replace it when its worn through.
aaron
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REPORT THIS POST AS INAPPROPRIATE |
Date Sep. 6 2007 2:56:24
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I use it a lot when doing marine fiberglass work. I am no luthier, but I wouldn't use it to fix my tap plate. That stuff cures by generating its own heat. Enough to burn your skin, and I wouldn't want that curing on my guitar. 