# Glue and Bending



## ervd (Oct 2, 2016)

I am looking mainly for education in this particular instance as I have not done many projects. I am learning as I go and sometimes questions pop in my head. So, I'm wondering if you glue a joint so that you make one long solid piece of wood, can that wood be bent by using steam? Will the steam melt the wood or is wood glue just that good? If it does melt is there a glue that can survive a bending by steam? I curious to know just how far joining wood and bending wood can be taken.

Thank you. Please educate me.


----------



## Finn (May 26, 2010)

What I have done is , using yellow glue, I laminate a number of 1/8" thick oak strips that I soaked in water for two days. While still wet, I glued the strips together and bent to the curve I needed and let it set for two days. Sanded the edges and it worked well.


----------



## mrbob (Nov 3, 2016)

I would think Tite Bond III would work since it is water proof. I just dont know how you glue end grain to end grain to make a longer piece and not have the joint break when bending, maybe a Scarf joint would work.


----------



## cathode (May 18, 2014)

PVA glues like titebond can creep over time. Mostly this won't matter but if the article is subjected to a lot of impulse force, it might creep faster / worse.

Powdered Plastic Resin (PPR) glue, aka "Urea-Formaldehyde" sets up hard like a rock and is incredibly strong and waterproof. Just wear an organic vapor respirator to filter out the small amounts of formaldehyde that offgas during the curing process.


----------



## Loren (May 30, 2008)

The way to do it is do the bend and then
do the joinery, imo.


----------



## shipwright (Sep 27, 2010)

+1 Loren. Why would you steam bend after glueing?
If the piece is going to be laminated, it shouldn't need steaming and vice versa.
For laminating, urea formaldehyde as mentioned above or hide glue will both resist spring back. PVAs will return a little.


----------



## Tony_S (Dec 16, 2009)

I think what the op is suggesting….? Is taking two short pieces of wood and joining them(scarf joint?) to make one long piece? And then steam bending?
If this is the case, I wouldn't try it unless the bend is fairly subtle. Sure, you could find a glue that would withstand the moisture and heat, but remember that your also softening both the lignin and the cellulose in the wood. I would suspect(because I've never tried it) that the joint would fail at some point, not because of the glue it's self, but because of the softened wood fibers AT the glue joint.

I just pulled that outta me arse though….pure speculation.

+2 Loren


----------



## Loren (May 30, 2008)

Often a bent piece curves a bit in its
cross-section. It's not very noticeable
normally but I imagine the reaction could
tear apart a scarfed joint.

That said, for machining purposes I would
experiment and see if it's easier to cut 
the scarfs before bending. I don't know
how a strap bended part in say, oak, would
respond to the material removal.

Once you start steam bending and see how
easy it is these questions will come up from
a place of insight. There are a lot of technical
problems that can be solved by bending easily
but also others that can be half-solved. Either
way, it's a great exercise in woodworking to 
join bent parts.


----------



## Tony_S (Dec 16, 2009)

> Either
> way, it s a great exercise in woodworking to
> join bent parts.
> 
> - Loren


Either steam bent or laminated, I agree.


----------



## runswithscissors (Nov 8, 2012)

As others have mentioned, you can easily laminate thin layers into a curve. But I've had excellent success by first using heat to bend the laminations, then gluing the pre-bent layers together. Advantage is your layers don't have to be so thin, therefore using less glue

Note that moisture is not necessary to do this. A heat gun is an obvious choice of heat for bending, though there are other good ways to do it. Let me emphasize: NO MOISTURE NEEDED.

As for using heat to bend glued laminations, I have also had good results using heat to bend plywood. This is fairly thin plywood, bent with the grain of the face veneers, not against. The heat is obviously softening the glue a little, as well as the lignin in the wood itself. If you glue together 2 such layers of pre-bent plywood, you get a very stiff and strong result.


----------

