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Epoxy du jour
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=3994		 Page 1 of 1
Author:  Evan Gluck [ Mon Dec 05, 2005 2:34 am ]
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Hi friends, I am looking at a Gibson SG with a previous headstock repair. The previous repair is a testament to the phrase SAY NO TO DRUGS!!! The people actually used plumbing caulk to try and hold this thing together! I never really use epoxy for a structural repair but I feel I need some serious gap filling abilities to make up for the amount of caulk I will have to remove.
   My questions are : What are people using these days for a strong gap filling epoxy?
Will it react to the nitro finish as it squeezes out?
What is the cleanup while it squeezes out of the joint?
Where can I get this miracle epoxy?
     Thanks in advance.
Evan
PS, we now know plumbing caulk is NOT a lutherie tool
Author:  Pwoolson [ Mon Dec 05, 2005 2:40 am ]
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West Systems makes THE expoxy that is appropriate for this purpose. It's pretty expensive but works great.
The epoxy won't harm nitro but the cleanup might. Denatured aclohol is the cleanup for epoxy and I've had it sort of blush nitro. Not a big deal as it buffs right out.
I might also recomend getting some silca beads to thicken the epoxy a bit.
Author:  Dave-SKG [ Mon Dec 05, 2005 3:42 am ]
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Evan, be cautious with the DA and if it blushes you might want to wipe on some Butyl Cellusolve...stuff works great. Just a quick light wipe.
Author:  Evan Gluck [ Mon Dec 05, 2005 10:30 am ]
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Thanks for the response, West System seems to make several types of epoxies. Any recommendation on which one to buy?
Author:  Pwoolson [ Mon Dec 05, 2005 10:49 am ]
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From what I understand, they make epoxy and finishing resin. Stay away from finishing resin, it doesn't have "glue like" properties. The hardeners are something like 205 and 207 (I'm not in the shop so I don't know for sure the actual numbers) one is fast cure one gives you longer working time. This time of year I'd go for the faster cure or you'll be waiting a long, long time for it to set.
Author:  PaulB [ Mon Dec 05, 2005 12:41 pm ]
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Is that a silicone based caulk? If it is you might have some problems getting the epoxy to stick.

Might be better to give it a miss.
Author:  Jim Watts [ Tue Dec 06, 2005 3:42 am ]
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PaulB, Paul W. is refering to fumed silica also know as cab-o-sil. It's used often to thicken epoxy resins to control the flow and enhance gap filling properties. No bonding issues to worry about.
However weara repirator if you use this stuff as it's a very fine powder and does contain silica which I don't believe is something very good for your lungs.
Author:  Barry Daniels [ Tue Dec 06, 2005 3:50 am ]
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You can easily cleanup epoxy squeeze out with mineral spirits which will not harm or blush the finish.
Author:  Shane Neifer [ Tue Dec 06, 2005 4:23 am ]
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Evan,

I have a Gibson ES335 that I inhereted from my grandfather. When it came to me the headstock was hanging by the headplate veneer. I used "Cold Cure" epoxy and it has been back together for about twenty years now. Epoxy is gapfilling. You can use almost anything to thicken it. THe neck is mahogany, I would use mahogany dust from one of your sanders as a thickener. I now use WEST SYSTEM epoxy as it comes with pumps that I like. I use lacquer thinner for clean up. So it will blend your nitro finish as you remove the excess epoxy. But the best thing to do is spray a could pieces of mahogany with nitro. Let them dry. Glue them together with epoxy and practice the the clean-up/polish process before your fix up your guitar.

My thoughts!

Shane
Author:  Barry Daniels [ Tue Dec 06, 2005 5:28 am ]
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Shane, lacquer thinner???? Why dissolve the finish just to clean up the epoxy?
Author:  Shane Neifer [ Tue Dec 06, 2005 5:56 am ]
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Barry

Just what I have used. Any of the alcohol based solvents that clean up epoxy will dissolve a lacquer finish. I haven't had any luck using mineral spirits to clean up epoxy. Just my experience and I have been through a few cans of epoxy woodworking and doing boat repairs. I do learn new things everyday though!

shane
Author:  CarltonM [ Tue Dec 06, 2005 7:40 am ]
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[QUOTE=Jim_W] ...it's a very fine powder and does contain silica which I don't believe is something very good for your lungs.[/QUOTE]

It's my understanding that silica, like asbestos, stays in your lungs for the rest of your life--which may then be shortened due to scarring, infection or cancerous changes caused or exacerbated by the silica. Treat it like a toxic material!
Author:  PaulB [ Tue Dec 06, 2005 8:38 am ]
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[QUOTE=Jim_W] PaulB, Paul W. is refering to fumed silica also know as cab-o-sil. It's used often to thicken epoxy resins to control the flow and enhance gap filling properties. No bonding issues to worry about.
However weara repirator if you use this stuff as it's a very fine powder and does contain silica which I don't believe is something very good for your lungs.[/QUOTE]

I was not refering to Mr Woolson's reply. I was asking what type of caulk was used in the dodgy repair. Plumbers caulk could mean any of a number of compounds, but if it was a silcone compound then even if it's removed there might be adhesion problems between the epoxy and the wood underneath where the caulk was. Pretty much the same as trying to glue a surface that has been contaminated with silicone polish. In which case a repair might not be possible without removing a lot of wood.
Author:  Pwoolson [ Tue Dec 06, 2005 8:43 am ]
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Mr Woolson? That's my grandfather's name.
I'm still curious what type of plumbing compound was used. I've never seen any type of plumber's putty that would even begin to hold a headstock under string tension.
Author:  PaulB [ Tue Dec 06, 2005 8:56 am ]
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If we can see a picture it might help. Our company rents lab space from Dow Corning, they make lots of different plumbers caulks. If I can get a picture I can show it to some of Dow's chemists in the lab next door and see what they've got to say about adhesion problems - if they can identify the caulk.
Author:  Jim Watts [ Tue Dec 06, 2005 9:18 am ]
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oh! Sorry, my misunderstanding
Author:  Evan Gluck [ Tue Dec 06, 2005 11:05 am ]
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Ok folks, here is the progress report. The caulk was put in over 10 years ago. My client was then afraid to put strings on it and stuck it in a closet. She then decided to use it again and brought it to me. My first job was to break the joint to get the caulk out. My method was simple and worked perfectly. I strung it up to pitch put it aside and waited.Within 2 hours the joint was seperated and I chiseled/dremeled with a wire brush the caulk to get to the bare wood. Due to the severity of the break I will put 2 mahogany splines across the break to be more secure. I have done this more times than I can remember on the very severe breaks and it never fails to hold. I am more curious about the epoxies gap filling properties. At this point I am sure that either Titebond or hide glue plus the splines will hold it fine. I just want to try the epoxy as an experiment.
Author:  Shane Neifer [ Tue Dec 06, 2005 12:33 pm ]
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Evan,

Do use epoxy. You don't, in my humble 25 years of all kinds of woodworking experience, need any splines if you have even reasonable wood to wood contact. Epoxy will gap fill and is much stronger than you will need (probably less than 200 psi?). A picture of the break will definately get you more precise advice though.

Shane
Author:  Evan Gluck [ Tue Dec 06, 2005 12:37 pm ]
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thanks for the advice Shane, I will definitely use epoxy for this. My wife is in Los Angeles with the digital camera so no photos for this one. Thanks again.
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