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Glue for HPL
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10137&t=50490
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Author:  Freeman [ Fri Apr 06, 2018 2:27 pm ]
Post subject:  Glue for HPL

I have a Martin DX1 with high pressure laminate top that has a detached bridge. What is the correct glue to reattach it (and vendor or source)? It is a clean failure at the glue line, I should be able to clean up the old stuff completely.

Author:  Chris Pile [ Fri Apr 06, 2018 3:14 pm ]
Post subject:  Re: Glue for HPL

I use Loctite Gel.... Make sure you shield the top around the gluing area (tape, or whatever) to keep the fumes from discoloring the top.

My thread here:
viewtopic.php?f=10137&t=48813&p=644069&hilit=loctite+martin#p644069

Author:  Freeman [ Fri Apr 06, 2018 5:03 pm ]
Post subject:  Re: Glue for HPL

Thanks Chris, I was thinking slow set epoxy but the gel CA makes sense.

Author:  B. Howard [ Sat Apr 07, 2018 4:59 am ]
Post subject:  Re: Glue for HPL

Is it a wood grain or a black one? The black ones are made from color-core PLAM material and do not seem to hold up when reglued.

Author:  Freeman [ Sat Apr 07, 2018 11:00 am ]
Post subject:  Re: Glue for HPL

Brian (and Chris) - it is the wood grained one. The original joint failed at the HPL interface - the bridge had a nice coat of some sort of adhesive but there was almost none on the top - only a tiny bit along one edge that scraped off pretty easily. I took every bit of old glue off of the bridge with a belt sander and scraping - the top is dead flat in that area so I made sure the bridge was too. I tried to sand the HPL with 120 grit to make sure it was glue free (and to rough it up a bit) - it was almost impossible to make any marks in it.

I did glue it up with gel CA, clamped with my usual cauls and got good squeeze out, which scraped off pretty cleanly. I am somewhat concerned about the ease that both the old and new glue scraped from the top - I'll warn my customer that it might fail in the future.

Author:  B. Howard [ Sun Apr 08, 2018 7:30 am ]
Post subject:  Re: Glue for HPL

Freeman wrote:

I did glue it up with gel CA, clamped with my usual cauls and got good squeeze out, which scraped off pretty cleanly. I am somewhat concerned about the ease that both the old and new glue scraped from the top - I'll warn my customer that it might fail in the future.


Yep, the plastic coating is tough tough tough, that's why PLAM is used for counter tops and floors. IME 50% of those wood grained that have been repaired will fail again. That is almost 100% for the black ones as the softer color core material deforms under the bridge with age so getting a good mating of parts becomes impossible.

You can cut the plastic layer off with a dremel and base so as to adhere directly to the high pressure core material which is actually designed to glue things to (like c-top substrates) and then almost any glue will work. But few want to spend that much for a bridge reglue on a $400 guitar.....

Author:  Frank Ford [ Thu Apr 12, 2018 10:43 am ]
Post subject:  Re: Glue for HPL

There's a good case to be made for bolts in this application, in addition to cyanoacrylate.

If you ever encounter one of those aluminum tops with a loose bridge, I suggest you consider bolts as a necessity.

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