Official Luthiers Forum!

I agree with Steve.
Also if you like the guys guitars, the way they play, sound, feel, look. If the builder has a good reputation (call his previous buyers) then why question his process? That's insulting if you ask me.


Sent from my iPhone using Tapatalk

_________________
My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

I open my boiled eggs on the small side.

_________________
http://www.Harvestmoonguitars.com

"Well I read this forum to learn but more specifically I am talking to a guy, very well known with a lot of guitars to his credit, about building a guitar with a Honduras back. He said he always wipes with acetone and uses epoxy with any rosewood cause its so oily. Id never heard of anyone needing to do that. I was wanting to get expert advice before I plunk down dollars. So you guys know and I dont, that is why I post so little.
I am under the assumption that the glue one uses is one of the small contributions to the sound. Thats what the whole Titebond/HHG controversy is about. Ive used a lot of Titebond in cabinet building and Im convinced from that, it may not apply, that Titebond is efficient but not a good idea for sound. I mean really it is liquid rubber. So youre putting a gasket between the brace and the back. Following that assumption epoxy is liquid plastic so it doesnt seem to me to be a good idea. Then again the glue used on back braces may not make any difference. They are just there to hold the back."


So are you wanting to have him build you a guitar, or is he helping - you - build a guitar?
Wiping with acetone and gluing rosewood with epoxy is not totally outlandish and some prefer it. It is not something I would do for back braces but then some things I do others would look askance at.
A number of years ago I started laminating old veneers to create affordable (and beautiful) back and side sets from woods that were no longer readily available - using epoxies and pressing them in a mold. I was not the first to do this. Many people saw this as an inferior way to build a guitar (to some it still is). Arguments were made about the detrimental effect of the glue, although no real proof of this was given. Today more people are building with laminated sides (and backs) and selling it as an improvement over conventional construction. What is the truth? It is up to you to decide.
If you don't like the way a builder builds, don't buy from them. But take what you read on forums with a grain of salt. Perhaps the glue does have some small effect on the sound, but a much greater contribution is made by the skill of the builder (who may have a few idiosyncrasies in their building methods). Ultimately it is your money and your choice.Try not to do something you will regret, whether it is to buy or not buy.

Good thoughts there Clay, thanks.

There is a big difference between quality epoxy and the stuff in 2 tubes that you get for consumer use

Now theres a different thought I didnt know. What are the good brands or conversely which ones to stay away from. That might make all the difference or at least be a good compromise.

I usually use West System 105\206. Although I have used System three T-88 as well. I use West system when doing falcate bracing, both for laminating and gluing the brave to a plate.

_________________
http://www.Harvestmoonguitars.com

System III T-88 here. And I've also used it for falcate bracing.

_________________
Steve Smith
"Music is what feelings sound like"

Sort of lost track of what this thread is about? But seems we have now moved into favorite personal epoxy choices. First and foremost one has to select the epoxy resin that is "suited for the job" at hand, there are many different formulations. There are plenty of first class producers Pacer, System lll, Bob Smith industries and on and on -- used most, all good. Dollar store selection not so much. I stay far away from the brands that required extremely precise proportions -- PITA

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

System III is finicky, but does the job well. Their clear coat is really clear and I use it for pore filling. I mix with a good digital scale and/or syringes from the pharmacy depending on how much I need. So far, knock on wood, never had a problem.

"I stay far away from the brands that required extremely precise proportions -- PITA"

What I have found is that precise mixes give stronger/ harder results. I mix relatively small batches by weight using a triple beam balance or even more precise scales.
5 minute epoxy doesn't require a precise mix but gives a relatively "rubbery" glue but I use it for non critical things (gluing in inlays and position markers, etc.)

Pacer, Bob Smith, and many other brands easy mix, work great -- not rubbery

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

I think you should take it down a notch, Ken.

I don't want to speak for the OP, but I'm always looking for hints on which epoxy people choose and why. Those who have a lot of experience using epoxy, please share!



I've used Z-Poxy, but not Bob Smith. Which do you use, the Finish-Cure? Do you use it for pore filling or also as an adhesive for falcate bracing? I assume Finish-cure is strong enough to bond structural elements, but I'm curious if you use the 5-Min Cure for bonding since you mentioned the "right epoxy for the right job".

The only reason I fiddle with System III is because it comes in slightly larger quantities (1.5 pint size) and the clear coat does seem to be almost totally clear. The Z-poxy seems to be quite amber. No deep experience with it, just what I've noticed when watching others mix it up for pore-filling and on the one guitar (Black Acacia) where the amber actually made the guitar look a lot like Koa.

I also saw someone use good 'ole West 105/207 as a pore filler. Looked pretty clear to me, and it can be bought almost anywhere. The problem is that you can't really buy just a little. $100 buys you a gallon of epoxy and a quart of hardener. That is quite a bit. Twenty five years ago I used West to patch sailboats, but that is like saying I used to use MS-DOS so I assume Windows is good. Is that a favorite of anyone here?

"Pacer, Bob Smith, and many other brands easy mix, work great -- not rubbery"

Thanks for the info Ken,
Good to know there are some quick epoxies that dry hard. I will have to try to locate those brands.

105 comes in quart size cans and they have matching sized hardeners depending on the mix ratio. I use it with both the 207 and 206 hardener. 207 works as a clear pore fill. I use 206 for structural bonds. I like the amber cast of zpoxy so I tend to use it more that 105/207.

_________________
http://www.Harvestmoonguitars.com

Finish resin is a specific epoxy formulation designed for bonding fiberglass cloth to the substrate which can be wood -- so Zpoxy is well suited for use as a pore filler. Bob Smith makes a similar product (Finish Cure) which I have not used. I too like the performance, easy mix and amber tint of the Zpoxy and see no reason to change brands.

For structure we have used products with different cure times from 3M, Loctite, Pacer/Zap, Bob Smith, Great Planes, Elmer's and several others -- all have worked very well.

I have read accounts were some have tried to use structural epoxy thinned with alcohol as a pore filler -- the theme is generally the same, results not so good.

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

Issues with Z-Poxy. After some body chemistry-induced minor separation issues with Z-Poxy and lifting of the Mohawk lacquer finish at free edges like the fretboard, we have gone to West 105/207 or MAS low viscocity for epoxy pore filling. While not an issue for most customers, we have found that Z-Poxy will be problematic for the same cohort with body chemistry that degrades nitrocellulose lacquer.

Sources. West Marine and Jamestown Distributors sell both brands, and both are amine blush-free and water clear when the hardeners are relatively fresh. West 207 will amber as it ages, but stays colorless for at least a year in our shop's experience. For West 105/207, a 1.33 quart kit with mini-pumps is around $105, and a 1.33 gallon kit with pumps is about $210. For MAS low viscosity resin with slow hardener, a 1.5 quart kit with pumps runs about $75, and there are 3/4 and 1.5 gallon kits available at pricing close to West product kits of similar volume of epoxy. Chesapeake Light Craft carries MAS and occasionally puts it on sale, so for builders located in the Baltimore, MD/Washington, DC area, a good option when combined with a nice waterside meal in Annapolis.

Mixing. Mixing is an issue with many epoxies - we never mix batches of West smaller than an ounce by volume, and usually use a precision scale versus the mini-pumps for anything under a few ounces...West 105/207 is a 3:1 mix BY VOLUME and 3.64:1 by weight...3.41:1 to 4.16:1 is the allowable variance by weight, which is within the accuracy of the mini-pump kit, but when we checked out our last pump kit (we discard hardener pumps after a year in service...cheaper than cleaning them), we were right at the low limit for the mix. It's certainly worth at least a check with a scale to verify the mini-pump kit's volume mixing is accurate enough for use.

Thinning. Denatured alcohol picks up 5% by volume water over time, and drug store isopropyl alcohol is usually 70% or 91% (30% or 9% water) as purchased, although it can be found at 99% from some sellers. The water present can interfere with curing and with physical properties, while any solvent added to the mixed epoxy in sufficient quantity to affect the viscosity may generally (per West and MAS) reduce bond strength in laminates, increase post-cure shrinkage and cracking, extend cure times, and alter the color of the cured epoxy. Neither West 105/207 or MAS low viscosity really need thinning, but for those that feel the need, heating the instrument BEFORE applying the epoxy is the best method, and as the wood cools, excess epoxy is drawn into the pores. An alternative is to keep the unmixed epoxy heated to 90-95 degrees and accepting the shorter working time in the mixed product, but the short-term reduction in viscosity makes little difference after the applied epoxy cools down to room temperature.

Heat Release and Post Cure. On heat release of epoxy, keep in mind that as mentioned, most room temperature cure conventional epoxies will release when raised above their glass transition temperature (Tg, around 116 degrees for West 105/207). If the joint is heated above Tg and release is not accomplished, the joint allowed to cool, then heated again, the epoxy will post cure, which MAY mean a higher temperature will be needed for subsequent release. 'May' is the operative phrase, as reduced cure times affect the change in Tg with post cure such that faster hardeners for the West 105 family see a significant bump up in Tg with post cure of fast (205) or slow (206) hardener, almost no change for 207, and a decrease in Tg for the extra-slow 209 hardener.

Re-gluing Epoxied Joints. Another interesting thing about West and MAS epoxies (and likely others) is that they will bond to near full strength with subsequent epoxy application with just mechanical surface preparation, so unlike Titebond, most common epoxies do an excellent job of sticking to already-cured epoxy provided there is adequate prep for good mechanical bonding. For both West 105/207 and MAS low viscosity, recoat without sanding can be done prior to full cure (usually 10-15 hours) with full chemical bonding, although slathering on multiple layers of epoxy is more a marine building task than it is in pore filling.

Whew! It's as though I wrote a book! Hope it is useful to at least a few of you!

_________________
A constellation only takes shape when one maps the whole.
- Beth Brower