Chemical bending- anyone done it?

[stuckinthemud]

I’ve seen a few articles on line about bending thin wood strips with vinegar and with alcohol.  Anyone tried chemicals like these to modify bow shape?

[Hamish]

Haven't tried it. I would do as much as I could to find out if chemical bending has any unwanted effects, like weakening tensile or compression strength(or perhaps even increasing them?).

With vinegar, you will likely get darkening/greying, a cosmetic change but I have no idea if it would affect to wood's suitability for a bow.

[GlisGlis]

Someone mentioned also bending with ammonia in the post about fuming.

here a scientific note:

Back in the 1960's, researchers discovered that wood could be plasticized by use of treatment with ammonia gas in a pressure chamber. The ammonia would dissolve the hydrogen bonds between the lignin and the cellulose fibers, allowing the fibers to slip past one another, and enabling extreme bends to be made.  When the ammonia evaporated out of the wood, fresh hydrogen bonds would form, setting the bend permanently in place as if the wood had grown that way.

[bjrogg]

Haven't tried it. I would do as much as I could to find out if chemical bending has any unwanted effects, like weakening tensile or compression strength(or perhaps even increasing them?).

With vinegar, you will likely get darkening/greying, a cosmetic change but I have no idea if it would affect to wood's suitability for a bow.

That was my first thought also Hamish

Bjrogg

[bjrogg]

Someone mentioned also bending with ammonia in the post about fuming.

here a scientific note:

Back in the 1960's, researchers discovered that wood could be plasticized by use of treatment with ammonia gas in a pressure chamber. The ammonia would dissolve the hydrogen bonds between the lignin and the cellulose fibers, allowing the fibers to slip past one another, and enabling extreme bends to be made.  When the ammonia evaporated out of the wood, fresh hydrogen bonds would form, setting the bend permanently in place as if the wood had grown that way.

That’s really interesting GlisGlis. I’m guessing it wouldn’t be quite as strong as “grown that way”. Little difference in layers, humps and bumps. Still very interesting.

Bjrogg

[Stoker]

Back 30 some years ago. I was building wooden fly fishing nets. I steam bent the wood. My sister gave me an article on using Downy fabric softener with water. Don't remember the ratios. It did work. Might have to google it.   

[mmattockx]

Someone mentioned also bending with ammonia in the post about fuming.

Modellers building radio control aircraft from balsa wood have used ammonia to help with bending of thin sheets of wood for decades. It works very well and doesn't seem to negatively affect the properties of the wood, but they are typically only bending it across the grain to form cupped or rolled shapes and do not ever bend it in the manner we do with bows. Ammonia would also be very obnoxious to work with in the quantities needed to handle bow sized pieces of wood.

OP, I would say if you want to bend thin laminations you can do that without much trouble with heat or steam and by keeping your lam thickness thin enough to allow the bending to not overstress the pieces. After all, even the extreme hook FG recurves you see out there were almost always bent onto the form with the lams being dry and unformed before the layup.


Mark