MIMF

Last night at our luthier's club meeting, I pulled the top off an old Harmony guitar and removed the ladder bracing, with the intention of installing X-bracing and repairing cracks etc. The guitar is nothing special but it is all solid wood (mahogany and spruce). The glue was a reddish brown color which to me did not look like hide glue. Does anyone know what type of glue it might be, and if it will pose problems when I glue the top back on? Of course, I'll get it all cleaned off as much as possible before that.

I am a big fan of these guitars, and your work will be rewarding as you will be surprised at how good it turns out if you do the work right.
I have heard that it's hide glue too, but there was a time when they changed over to a glue that is opague red/brown and it's too gooey to be hide glue. Nasty stuff that. I have an early 60's late 50"s Harmony in my shop right now and it's got hide glue but the stuff you are talking about sounds like the newer glop they used. Just get as much of it off as you can. Clean the whole guitar out of any of the glue squeeze-out, they were not worried about being tidy back then.
Maybe someone else knows what it is, but I say just don't worry about it and get rid of it as much as you can.

You might try some De Glue Goo on some to see if it softens it. It works on most wood glues.

Hobbiest here, not a professional.

Brown gravey glue ( hide glue) as I remember reading about it before. Look closely, the roast beef and mashed potatoes may still be in there.

I can't remember where I read it , but I read that Harmoney never cleaned their glue pots, only added more pre-mixed and water in-between.

I have had a number of these units opened and re-glued with fresh hide glue and had no issues. I swear you could recover enough ooze out, re-liquidfy it, and put it back together with "vintage all original materials".

Have fun.



It releases with that distincitive crackel sound.

John, you seem to be describing the hide glue all right but the other brown stuff isn't so hard and won't make a crackly sound and will not crumble, it's too gooey. I should probably not say "gooey" but rather just a bit rubbery and too soft, and I don't think that water will dissolve it. If you're lucky enough to get a Harmony with hide glue that's fine but the other stuff isn't quite as easy to work with but it can be done. Just clean it off.

Ah well, it did crackle and crunch when releasing - definitely hard. Next time I have the guitar down off the shelf I'll try to dissolve some in water and see.

I was informed that the hard crispy, often bubbly reddish brown stuff is Resorcinol, the same stuff exterior plywood is put together with. I don't know of anything that will dissolve it.

I agree, it may be Resorcinol; not a very pleasant stuff to use. I don't think switching to hide glue or another more conventional one will have a detrimental effect on the repair, even if its not the original type; especially if the original one is not very safe to use.

I restored a 1960's all birch harmony tenor earlier this year. I have no idea what the glue is, but I couldn't get it to release with heat/moisture and I couldn't dissolve it with solvents. I ended up cleaning the squeeze out with a cabinet scraper and used a sharpened putty knife to seperate the bridge patch that needed replacing. The stuff is very brittle and crumbles everywhere.

Not sure what the glue is but I have steamed open several Harmony Soveriegn guitars to fix the neck bowing and the glue dissolves pretty well under steam pressure. BTW I have had a lot of success in retro-fitting these guitars with bolt on fittings for the neck. This allows me to get the action just right. Nice wood in these guitars albeit under constructed from a bracing standpoint.

Necks are usually put on with reversible glues, even some Gibsons were assembled with Resourcinol but necks were glued with reversible glue.

I am in the process of rebuilding a "silvertone" arch top made in 1957. It was left in a shed and came apart everywhere so decided to use it as a practice rebuild. I do agree that the glue could be a recorcinol type of glue. From my experience this type of glue is water proof and somewhat heat resistant. I just attacked it with sharp chisels and scrapers.

The only remaining part of the guitar im saving is the top, back and side set. Like you said earlier, "solid materials". Ive made a new neck and fret board and I did not try to save the binding either.
Sounds like fun!