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I have a project that requires me to periodically put some glued up wood into a low oven. For some simple, out-of-the bottle glues, what temperatures are safe to not have a glued joint come apart?

I think that Titebond III is more heat resistant. Check that out.

What temp is the oven going to be set at?

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Old growth, shmold growth!

JB Weld slow-set epoxy would work if I remember correctly how hot a "slow" oven is. Dark glue-line could be a problem. When I tested several glues for laminating wood before bending it, I found that PU glue held well when heated to bending temperatures. (Can't remember which one I used, but it wasn't Gorilla brand.)

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The appearance of the item is not important. I am drying things positioned on it, so it is like a form. The oven might be set at 200 or less, but I worry about spots of radiant heat being hotter, and also that I might set the temperature wrong. I cannot use epoxy, because I am severely allergic to it.

I'm not sure if Resorcinol glue has higher or lower heat resistance than epoxy ... definitely not as good gap filling capability, but worth researching as far as heat resistant specs are concerned.

You shouldn't trust any off the shelf glue at 200 degrees without testing them. There are plenty of epoxies available to you that will easily be able to take that temperature but I wouldn't assume anything without conferring with the manufacturer about their cure cycle, heat distortion temperature (HDT), and glass transition temperature (Tg)....and then follow their schedule. Many epoxies will come apart in the low 100's and some, with proper processing, will withstand fire.

JB weld will probably work fine but you'll need to join the part, let it harden overnight under clamp pressure, and then bake it at or above the intended 200F (or whatever you think it will see) for maybe four hours....letting it cool off overnight....keeping the clamps on the whole time.

Do a little test on scrap following that profile. Then heat it up again after the initial schedule and try to pull it apart after reheating it to 200. It's the only way to know.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Not sure what you mean by simple glue but fish glue is good to 500f. Just keep it dry. LMI and Lee Valley carry it. At one point John at Bluescreek had it also.

Hide, Fish and powdered resin glue (Urea glues) can all withstand serious heat. I think powdered resin glues are waterproof too.

Resorcinol is the gold standard. After a room temp cure (Weldwood for example), it will hold the parts together while they're charred, or steamed or soaked for years (hence the Navy mil-spec for use below the waterline). To test it, I edge joined two pieces of Indian rosewood, thicknessed the piece to 3 mm (.120"), soaked it for 15 minutes, then bent it on a very hot pipe 180 degrees on a 1" radius (perpendicular to the glue line). If you need that kind of durability, Resorcinol is worth the careful measuring and application it requires.

When I've used fish glue for purflings, they've tended to separate on the bending iron. I don't know what I'm doing wrong, but I haven't had good luck.

I've just started experimenting with Titebond III for purflings. It seems to hold up well to moderate heat and some moisture (a combination that's out of the question for fish glue or hide glue.)

500F? Really? Wood, once totally dried out, starts combustion at around 540F. How would you ever remove a bridge glued with fish if that were the case?

Add Moisture!

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Waddy

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Here's the tech sheet from the manufacturer: https://www.norlandprod.com/fishgel/hightack.html

It's not appropriate for bridge attachment. Water/Steam reverses it much easier than any other glue. I like the long open time feature of it for top attachment, severed head re-attachment and the reversibility feature for neck attachment. It dries very hard and needs a very good seal coat to protect the joint. I live in a sauna during the summer and have had no failures.

As far as it coming apart while bending, you have to wait for the parts to dry completely (like 2-3 days in a dry location) and not pre-moisten. Otherwise, steam loosens the bond.

Wow that's impressive. I had no idea. I think I will start using this on top center joints on my Selmer builds as I like to heat bend the pliage in after joining the tops. IIRC LMI white's flash point is at around 250F so I had to be real careful and keep it around 220F in the process. I just started using Fish about a year ago and I really like it for all the reasons people like it for. I've used it on bridges and so far so good. I just started an experiment where I glued two pieces of walnut together with Fish and will hang it from a weight on a tree outside in the humid Virginia air and see how it holds up. After reading horror stories and success stories I want to know for my self. I like it for bridges as it tacks well, is super easy to clean up and has plenty of time to get it right.

I use fish glue from LV , but as J. romanillos mentions in his book jointing tops with fish leaves a distinctive glueline. I use HHG for tops/backs and fish/hhg for bridges , linings , FB, rosettes, bindings/purflings it/s drier here in KC than the e. coast. abt 40-45 in my shop

Better slow your roll on Resorcinol, IMO. The cured glue line is burgundy red. On a spruce top it would look horrible. Then there is the hazardous nature of this glue as well. One MSDS I found listed PEL limits at 10 ppm.
Gibson used Resorcinol for flat-tops for a brief time in the 60s. You can see the squeeze out around the braces on these guitars that looks like dried blood. I heard an interesting story on NPR a few years back. Raul Malo had some of his guitars stored at Soundcheck in Nashville. When the Cumberland River flooded and inundated Soundcheck many guitars were submerged and destroyed. When Raul was able to gain access to his gear he found his favorite J-45 (from the Resorcinol years) was completely filled with water. He dumped it out, took it home and hung it up to dry. After a few weeks when all the water evaporated he found that the guitar had suffered no damage and played exactly as it had before being submerged. An impressive story, but I am still not going anywhere near Resorcinol.

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