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My 105 resin and 207 hardener arrived. Pump kit too. I'm using this for the top and rosette fill. My intention is wash coat for top. I'm used to z-poxy which is easily thinned with DNA. Is this true of West System? Can thin it with DNA?

Did you see this?

http://www.westsystem.com/ss/thinning-w ... tem-epoxy/

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

West System is pretty low viscosity as it is. I've been using it for 25 years, and the only time I've ever felt the need to thin it (we used acetone for quick evaporation, but alcohol can work with very thin coats) was to lower viscosity for spraying.

Are you sure you really need to thin it? I would try some on test pieces simulating your working conditions first, and you may find it to work fine as is.

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Eschew obfuscation, espouse elucidation.

Mike - I'm wondering how you will treat the area of the top where the bridge will sit. Do you typically have that area masked off during finishing?

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Thanks Kevin. I read your link.

My reason for doing this (using epoxy on top) is primarily for the rosette fill and level. No CA for me. I realize a properly sealed channel will minimize CA wicking into fibers, but even then I had unexpected yellow streaks due to CA reacting with spruce. Never going there again. I will work some test pieces.

There will be no significant build of epoxy anywhere except in any rosette gaps (very small). Most will be sanded away, I'm taking Haans' advice to stiffen top fibers and slightly pop the grain. I am using water born Enduro-Var, I do not want to use shellac on top (actually, General Finishes discourages that anyways). I do not want to take a chance on raising the grain. Don't think "pore fill", but more of a wash coat or seal coat.

Been using West System on guitars for eight years and have applied it on nearly 700 guitars and not once have I had a need to thin West System epoxy. I just don't understand the benefit or risk of failure in doing such a thing.

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jw ( o)===:::

It was a question. I have zero experience with West. For some, application of a final "wash coat" (z-poxy) is used. Thinned with DNA. I was wondering if such was done with West. Z-Poxy has a certain color tone to it rather than being clear like West. Sometimes a wash coat of z-poxy can even colors out after sanding. For this reason, I may be interested in using West as my only epoxy pore fill. Regardless, this discussion is veering off course as I am not talking about back & sides.

I've used many gallons of the stuff.

Heat will lower its viscosity more reliable than any sort of solvent or thinner. Many users find it easiest to put the cans of resin and hardener into a warm water bath ahead of time. You can also use a hair dryer selectively and carefully. If you get it too hot it can actually boil and go white. You don't need it that hot. Heat will also cause it to cure faster.

I also find mixing by weight more reliable than the pumps. Fresh pumps are generally OK, but when they get older they can pass air.

Plastic beer cups are the cheapest mixing cups!

If you are planning any kind of coating, elevate your shop temp above normal before you use it, then let your shop slowly cool back to normal. This way your wood will not be off-gassing while the epoxy is on it. This will cause bubbles. If your shop is in a state of generalized cooling, then the gas will already have been pushed out of the wood and it will be returning into the wood.

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"I also find mixing by weight more reliable than the pumps. Fresh pumps are generally OK, but when they get older they can pass air."

I have also found this to be true, especially with the small quantities of epoxy we generally use. The ratios by weight are different than the ratios by volume so read the can carefully.

You know Mike if evening out the color is a goal sizing the top with egg whites is an option too and a very safe one as well. I took Robbie O'Brien's excellent Red Rocks French polish class and he touched on it then and we all tried it. It can really even out things as well and no fumes!

That's a very good point Hesh.

I was not only referring to back and sides. Tops, both cedar and spruce, necks, bench tops and even the ocasional new t-shirt (doop)

I think if you do a little testing Mike, you will find West epoxy very easy to work with just as it is without compromising it by thinning. As others pointed out, skip the pumps. They work pretty well but one pump of the epoxy would pore fill about 20 guitars, wayyyyy too much epoxy. Using a scale is nice. Glass syringes are an awesome way to mix small amounts that we guitar folks tend to apply. As far as volume of mixed West, about 2cc will easily coat a guitar top or back.

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jw ( o)===:::

Well, ok then! Thanks

Think I'll use the scale

Yeah, I haven't used the pumps since my days of restoring old hydroplanes, 20+ years ago.

I typically use a balance scale, but it can also be very handy to keep some in graduated syringes for quick small jobs. A 5ml syringe for the resin and 1ml syringe with hardener makes for some quick and easy mixing when you need it.

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Eschew obfuscation, espouse elucidation.

In my experience, excessive thinning of West 105/206 with DNA will cause the epoxy to harden only to a somewhat rubbery state. You should test the degree of thinning that you have in mind by allowing an experimental mix to set up in a thick layer. If it sets up to a normal glass-like hardness, then it is probably safe for your non-structural use.

I was going to say the same thing. For the little quantities we use, nothing beats a syringe (10ml is a good size too) for measuring out exact quantities.

Mark one for hardener and one for resin and you can re-use them almost indefinitely.

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Kevin,
Good article. I thinned epoxy just one time for a neck. Didn't work so good. I suspected something like that was going on.
Thanks for posting

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Joe Beaver
Maker of Sawdust

Weird. My 10.6 fl oz can if 207 hardener was not full to the top. About 2/3 full or a bit less. Is that expected?

This stuff is quite different from z-poxy. Thinner. More prone to out gassing. Like it though. I worked a little into the top, then just wiped it off. Nice seal. Thinning was not needed.

They don't fill it to the top. The volume of the can is more than the ratio that is required for the volume of the resin.

_________________
Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

Thanks. Good to know. Maybe it says that on the can somewhere, or website.

Edit: it is mentioned on the can.