Steam Vs. Heat bending

Steam vs. heat bending, which do you prefer and why?

Steam bending is a good way of making thin wood crinkle up like a crisp (or potato chip for US readers). Not my choice for my ukes.

OTOH, steam bending is much better for building boats.

Sawdust,

As ProfChris points out, its all about control. Thin pieces in a conventional steamer will release their stresses in all directions, resulting in multi-directional curl.
Luckily for us, thin pieces will bend before they char, (mostly), when applied to an iron. This is only true up to a point of thickness where they will char long before they bend. This is why it is necessary to steam cook larger cross-sectioned pieces for long periods before they become supple enough to bend.
Some luthiers utilise steam in 'iron' bending by pre-dampening the pieces, others do not. This may be a species specific choice. I give everything a light misting.

The upper bout on this guitar is the last time I charred a side.



The rest of the bends I used a thicker damp rag and draped it over the iron. I then rocked the side on the rag, as the rag dried out I moved it so another damp section was over the iron.



So as long as the rag is still producing steam you will never burn a side. But is 212F (100 C) enough to bend wood? I haven't done a rosewood on it but cherry, maple, spruce (tricky), seem to work. the reason for steam boxes is because the wood is thicker and you have to wait for the heat to get into the wood. Also water (steam) lowers the temperature (a little) wood starts to go plastic. Some people use higher temperatures but mist the sides, others lower and dry. There is no right way, the added moisture keeps the temperature down until it evaporates and then the temperature climes. So if someone mists the sides in a side bender the blanket may be hotter until the water evaporates. Wood that has a lot of runout (the fibers in the wood are cut across, think of curly maple, the reason it looks wavy is because the fibers are at a different angle) allows moisture to get in between the fibers and when bending the wood cracks. So sometimes dry is better. Just a few thoughts.

There are times when I have used steam in conjunction with a heating blanket to bend difficult, valuable rosewood. it does help. I got the method from a Robbie O'Brien Video.

https://youtu.be/rqSglfu6xtA

I have seen videos of steam bent uke sides that were very successful.

DPO said:

I have seen videos of steam bent uke sides that were very successful.

Click to expand...

It can work, but needs careful wood selection and a form to clamp the sides to.

Dry heat (with maybe help from a damp rag) on a bending iron is less risky in my view, plus you can bend freehand.