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I'm using West System G Flex Epoxy for the first time to glue the fingerboard to the neck. I have used various manufacturers epoxies for years without a hiccup, but this one is not behaving as I expected.

I have always gotten away with visually estimating equal portions of hardener and epoxy. I tried that this morning, but after three hours, the epoxy was very tacky but not set. I thought, "okay, this stuff is temperamental." So I cleaned it all off and mixed up a new batch using a digital scale to make sure I had equal parts, and went at it again. Four hours have passed, and I am at the same point I was this morning. Both the epoxy on the guitar and the left over epoxy on paper are very stiff and very tacky, but not set. The instructions said the epoxy provided 75 minutes of working time and cure hard at 3 hours.

My room is 69 degrees, 50% humidity. Does this stuff take forever to cure or have I mixed up a bad batch again? Five and thirty minute epoxies have always been so predictable.

Thanks,

Ken

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http://www.casperguitar.com

I've only used West 105 resin with the various appropriate hardeners. 3-4 hours is nowhere in the picture of cure time. I always plan for overnight at the least. Lots of heat hastens things considerably.

3-4 hours is very optimistic.

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Expectation is the source of all misery; comparison the thief of joy.
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It seems that many people use epoxy to glue the fretboard to the neck. Is this necessary? I have just been using the white LMI Instrument Maker's glue or Titebond.

Ken my friend with West equal portions are not the ticket.

I have the quick fix, pre-measured packs of 105 and 205 in front of me now and the pre-measured, use-it-all packs contain 13.75 ml and 2.75 ml respectively. To be clear that is 13.75 ml of the 105 and 2.75 ml of the 205.

This sounds like why you are experiencing what you are. This is perhaps further evidence that more hardener does not make for a harder cured epoxy.

Alan some us use epoxy because at times water based glues, HHG, Fish, Titebond, LMI White, can warp a neck. I got away with it without using epoxy a bunch of times and then I did get a warped neck. Now I use epoxy and the results are a very straight neck.

Whoops I just reread your post and you said "G-flex" perhaps that does call for equal portions - I'll look it up and see.

EDIT: I'm back - yep G-flex is a 1:1 mix ratio - sorry for my lousy previous post.

I found this Ken:

"A toughened, versatile, liquid epoxy for permanent waterproof bonding of fiberglass, ceramics, metals, plastics, damp and difficult-to-bond woods. With a modulus of elasticity of 150,000 PSI, it is a bit more flexible than standard epoxies and polyester, but much stiffer than adhesive sealants. This gives G/flex the ability to make structural bonds that can absorb the stress of expansion, contraction, shock and vibration. It is ideal for bonding dissimilar materials. It can be modified with West System fillers and additives, and used to wet-out fiberglass tapes and fabrics. Mixed at a 1:1 ratio, G/flex gives you 45 minutes of working time at room temperature. It reaches an initial cure in 7 to 10 hrs and full cure in 24 hrs. Click for photo. (8 fl. oz. / 236 mL)"

Maybe at the 24 hour point, if you are not there yet, and it is not fully cured it may be old stuff. I always struggle with finding sources that rotate or sell enough CA and epoxy to know that I am getting fresh stuff.

Also, not being very experienced with epoxy here when I started using System III I went to their site and read the FAQ looking for a shelf life. What I found was some cryptic incomplete answer indicating that their products should be fine for about a year...... That concerned me......

Thanks for the replies. I hate moving to new new adhesives--Same thing goes for finishes. I was out of my usual 30 minute epoxy. All I had was 5 minute, and I didn't want to use that short cure stuff on the fingerboard. I saw the threads on the West System, so I thought I would give it a go as a hardware store in Ann Arbor had some, and it was a get day to get the car out yesterday for a short jaunt.

Hesh...Initial cure in 7-10 hours! No wonder it was still tacky. I could probably have left my first batch alone. I wonder why the instructions say hard cure in 3 hours?! Hmmm! I checked the epoxy a few minutes ago, and it is starting to take. It is no longer soft, still a little tacky, but I think it is going to cure. Whew!! I never would have thought of such a long cure time. Lesson learned.

Alan...I wanted to use epoxy to prevent warping. I use titebond to attach the headstock plate veneer and got a slight warp/cupping. I didn't want the same thing to happen to the fingerboard. I have never tried to release epoxy by heating, but I understand heat will release the joint if needed.

Ken

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http://www.casperguitar.com

Ken,
I don't think that is the best epoxy for your application. I would be afraid of creep with a flexible epoxy. The regular laminating stuff that Hesh mentioned would be better. I would use the base resin with the fast hardener. I think that is the fast hardener that Hesh has. These epoxies have enough latitude to be mixed by volume if you are careful. They also have a metering pump system that works really well. Never had a problem using the pumps.
I would use this resin with the fast hardener for most of you guitar building needs. That "fast" still has plenty of open time. If you need more info and or tips P.M. me I have a lot of epoxy experience.
Link

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Cut to size.....Beat to fit.....Paint to match.

This is so the way to go BTW. No muss, no fuss. I'd say that there's enough epoxy in one pack to apply a coat for pore fill, do a fret board and you'll still have gobs left over.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Thanks for the offer Link. The stuff I have is going to have work for this guitar as it finally is setting. Hopefully it works out okay. I'll looking into the resin and fast hardener for the next go round!

Ken

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http://www.casperguitar.com

I agree. The pumps have always been dead on for me. I use 105/205 (fast cure) and 105/206 (slow cure) and both work without a hitch. One squirt of each and that's that.

I always use West Epoxy for fbs. I am a big fan of this glue.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

What about Smith All-wood, at LMI?? Compared to West packet stuff???

http://www.lmii.com/CartTwo/thirdproduc ... Wood+Epoxy

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Here is what a Parlor Guitar is for!
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http://www.shopmaninc.com/polyesters.html

Guys here is a link to epoxies that I use thought not in the guitar field. I make competition rifle stocks and have made balsa and carbon composite stocks that are wrapped with one layer of carbon on the outside that withstand the recoil of centerfire rifles using this material. I don't have an idea if this will translate into useability (is that a word) for guitars, but it should give you and idea as to how good this epoxy is.

One note of caution on this epoxy. It is not water clear like some I have used, but has an amber cast to the material. It always seems to dry clear, but that has always been over carbon fiber twill!

Mike

I gave up on the pumps years ago. They work fine for awhile, but then once they start to go off you can never really trust them. I now use a scale which works all the time. Unfortunately, for me, its in Imperial measure. No matter, its just an issue of personal prejudice.

0.25 ounce to 1.25 ounces, or whatever multiple is required. Mix into beer cups.

I'll not be going back to the pumps. One other thing with them is that you have to systematize your counting so that you are always correct. The best way is one pump resin to one pump hardener, then repeat as required.

Don't count 5 pumps resin and, um, how many times did I press the hardener pump?

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

I've never used the G flex, so I don't know about it. I've always used the 105/205 combo and I just love the stuff. Just finished gluing up a fb a few days ago and I'll never use anything else. Note that I use the 406 Silica filler when working with hardwoods. It cures as hard as glass and I'm always tempted to build an entire guitar using only West... I know the clamping time would be counter-productive, but it's not like it's a race anyhow, right?

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I'd like to be able to prove, just for once, that money wouldn't make me happy...

For those using the pre-measured packets, are you referring to the kit West Systems identifies as a 101-6 Maxi Repair Pack?

Here's a link: http://www.westsystem.com/ss/105-system-kits

Thanks,
George :-)

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George :-)