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I am attempting to make bracelets for Christmas presents out of scrap binding and purfling. I am having issues with the glue delaminating during bending. So far I have tried using Titebond Original and CA glue just because that's what I have in the shop. I have to make a very tight bend (about 3/4" radius) so I have to really lay the heat to it. I also spritz with water. Is there a good heat resistant, flexible, and water resistant glue anyone could recommend? I need something that will withstand about 350 degrees F. and light spritzing of water. I am considering Titebond III, or an automotive silicon adhesive like ProSeal RTV or similiar but I'm not sure it would work on wood. Thanks for any advice.

Most glues will let go before you get to 300 degrees. I doubt automotive silicon adhesive will do the trick. A) go thinner; B) bend cooler; and/or C) rethink the design so you're bending a single piece at a time.

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Aaron Craig

I have been told that Gorilla Glue will hold up on a cracked side when bent...never tried it myself, but may be worth a try

Titebond 2 and 3 are both heat resistant. 3 is also water resistant. I've been using 3 for years for gluing binding and purfling together before bending. I would give the 3 a try and see if that works for you.

Josh

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Josh House

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I don't think any of the Titebond glues will hold at 350 degrees. There are some high tech epoxies that are rated to be heat resistant, but I don't know much else about them. I talked to a guy at a craft fair many years ago who made beautiful belt buckles using wood and metal. He said that he used a dental epoxy that was very heat resistant.

I used Titebond III to glue the back plates on a carved upright bass because there is a bend across the upper bout ala Panormo. It worked great and have had no problem. I recommend Titebond III. Pals, Vic.

If those glues don't work for you, you can try resorcinol resin glue. It requires careful measuring, and it is a dark red brown, but it will stand up to any amount of heat and water. I tested it out on Indian Rosewood--edge glued two pieces about .150" thick, soaked them in water for fifteen minutes, then did a 180 degree, 2'' diameter bend on my bending iron. I scorched the wood, but the glue held fine.

Eric, do you have a brand name for your resorcinol resin glue? I used to use an outstanding product call Aerodux 500 when I was building boats - just about as bullet proof as glues get - but it seems no longer to be available. Aerodux 500 was a urea-resorcinol-formaldehyde glue iirc and left the dark glue line you see in WBP plywoods.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

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I gotta go with this vote. Think of this - if the glue holds, you shouldn't be able to bend because the radii are different for the various strips of binding you're bending.

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Weldwood is the brand I've used. They make several different glues, so be sure you're getting the resorcinol. It has become much harder to find here too. This site seems to sell both the Weldwood resorcinol, and Aerodux 500: http://www.chemical-supermarket.com/Weldwood-Resorcinol-Structural-Adhesive-p117.html

Cascophen is another brand. You can buy it here:http://www.aircraftspruce.com/search/search.php?s=resorcinol+glue&x=22&y=9

Thanks, Eric! I've used the Cascophen too, but preferred the Aerodux, though I can't recall why, now. (It was 35 years ago; that's my excuse and I'm sticking to it!). If anyone wants to use a seriously permanent glue, one of these will fit the bill.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Google "high temperature epoxy". You won't find very many things other than epoxies that take that kind of heat.

There are a lot of epoxy products that will take the temperature but don't use anything unless it says it will take 350 degrees. Many products labeled "high temperature" are rated at 250 degrees.

The other issues are whether or not the glue is visible and whether or not the color will work with what you're doing. Most high temperature epoxy adhesives are filled...which means it will be an opaque color. You might also find a laminating resin meant for that temperature that will work as a glue.

And lastly...after an hour or so a lot of woods discolor with that much heat.

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StuMusic

Thanks for all the great ideas so far guys. I will look into the resorcinol and high temp epoxies. I may go pick up some Titebond III at the hardware store and give it a shot, with less temp. I have tried bending the pieces before gluing but it's a PITA to glue them all together after they are bent. It's much easier and cleaner to glue them up flat, run them through the thickness sander a few times, then bend. Goes a lot quicker and cleaner this way. I thin to about .050" which seems to be about the right amount of flex and strength. I might go just a bit thinner. The easiest solution though is to use stronger glue.

Andy you are right about the different radii. I tried bending a few laminated together and it didn't work. My current method is to edge glue the binding and purfling together, thickness sand, then bend (all pieces are at the same radii), bend the backing strip separate, then glue it on. This seems to work ok, but the binding/purfling comes unglued.

Titebond should work fine if......

the glued, bent peices need to remain under pressure or at least tight contact, until the glue cools following the bend. It should rebond by the time it is back to room temp.

At least that is my thinking but I could be wrong.

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Joe Beaver
Maker of Sawdust

Joe- you are correct. All PVA adhesives, such as Titebond can be heated and will regain their strength as they cool. The reason: They are plastic and around 300 degrees F they will actually melt.

It is definitely worth reconsidering the method in this case as there are very few situations in which bending a lamination after gluing is advisable. Bend the parts first, then apply adhesive and possibly put it onto a form in order to achieve the final shape. If you want to speed things up and have an old microwave that is no longer used for food: grab some Titebond II, lay up the laminations, and place it all in the microwave along with a mug of water (to prevent scorching from any excess energy.) At full power it will take a matter of perhaps 30 seconds at most to fully set the adhesive. Give it a minute or two to cool down (aka dwell time) and the joints will be good to go. This is a very basic form of RF curing. Titebond original could be used but it will take more time. Catalyzed HPVA type II adhesives such as TB II contain small amounts of aluminum which will reflect the microwaves and focus more heat in the gluelines. While TB III could be used it is not recommended for RF because of its excessive thermal plasticity... Which is a fancy way of saying it loses more strength at elevated temperatures than most of the other Titebond adhesives.

Hugh, are you suggesting doing the microwave thing before or after bending the laminations?

Well, I got some Titebond III at HD the other day. I also picked up some JB weld epoxy because it claims to hold up to 500 degrees. I tried them both on separate glue ups and they both delaminated when trying to bend on the hot pipe. I think there isn't enough gluing surface to hold good contact (.050" of edge gluing). On the next batch I will either continue doing it like I have been and accept that I will have to CA glue the pieces back together when they delaminate, or bend all the pieces separate then glue up, possibly using a form like Hugh suggests. Probably the latter. The end result of this batch was pretty good though. Thanks for all the tips.

Those look very nice, Gil!