`flame torching' bamboo

[mbaker]

Does anyone have experience with flame torching bamboo? I have read recently that it helps prevent cracking and splitting. This apparently is a technique used by fly rod makers.
Thanks for any advice.
The drum stick guy!

[Mark Meckes]

Hi!
Here's a thread on...Heat Curing/Tempering Bamboo (http://www.bamboocraft.net/forums/showthread.php?t=338) that dwells on some basic principles and techniques of heat treating bamboo.
Flame torching is an interesting name for this! At one time I called it `Flash Curing', though this brings up other connotations! Then I heard the term -`heat tempering', and like the similarily interesting things that can happen playing with heated steel, that term has stuck in my mind.
Now, when it comes to heating bamboo, there's a lot ways to produce and apply the heat, and for many various and specific reasons, so undoubtably we we will come up with some interesting terminologies!

I've been using heat on some of my carvings to an extreme measure, that is, to make the bamboo expand and open wide up. The process completely relaxes and releases any pent up tension in the bamboo. When it cools, it retains a balanced equilibrium. Less stress in the bamboo means less stress during carving, when an unexpected crack or breakage can turn an otherwise satisfactory accomplishment into a botched job!
I'm in the middle of putting pics and notes together on this current years projects... meanwhile, here's an example...

Letting go/Getting away
http://www.bamboocraft.net/gallery/data/3038/thumbs/1040605-066F.JPG (http://www.bamboocraft.net/gallery/showphoto.php?photo=862)

Mark

[Angel]

Anybody know of any scientific research about gas torch bamboo heating proccesses?

[Mark Meckes]

Hi Angel, This would be looked at in many ways, depending on the objective or purpose for using this treatment in consideration of the final bamboo product.
For example...
To heat clean, color, texturize and provide a lasting finish to the bamboo
To preserve ...against what?
To make the bamboo more resistent to cracks and splitting.
To make stronger for structural purposes
To bend and reshape the bamboo.
To affect the flexibility and memory of material (returns to original point after bend), as with bamboo fishing rods.. or to harden the `prong' of a bamboo jawharp.
To make the material more resonant to sound.
... etc
The gas torch bamboo heat treating process covers many fields and is employed by artisans of many skills who notice many subtle differences, because this is their profession and trade.
The scientific community can gain knowledge and insight for continuing research, to determine the how what where when which and whys.

There are so many countless variable angles and factors, this work may take a while. LOL

Mark

[Mark Meckes]

This picture shows different rates of contraction during drying of a (gas) flame torched piece of green bamboo.
http://www.bamboocraft.net/workshop/data/518/medium/TorchCured-120.jpg
This bamboo (Phyllostachys rubromarginata) was tempered in a green state with a gas flame, propane torch, in the round.
Then it was cut into strips with a bandsaw, and allowed to air dry.
See how the middle portion contracted upon drying, whereas the outer and inner shell remained rigid.
Added note... Because bamboo has an outer and inner `shell' of a different density and structure, I will take a guess that flame torching draws out the `juices and waxes' to these surfaces, and when cools, hardens, or make them more rigid or firm...
(yes, it would be nice to give these juices and waxes a scientific name!)

Have started a new category in in the Bamboo Workshop Gallery called...
Heat Tempering / Curing Bamboo (http://www.bamboocraft.net/workshop/showgallery.php?cat=518)

Mark

[Angel]

Well, about heat torch and color, this image
http://www.bamboocraft.net/gallery/data/3057/thumbs/MVC-811F.JPG (http://www.bamboocraft.net/gallery/showphoto.php?photo=2068)
shows that color obtained by propane torching bamboo is decolorated by sunlight. I had these bamboo for about 6 months, indoors, in front of a window that received summer sunlight at morning.
Someone might use this slow technique to get some arty work!!!

[Mark Meckes]

This is amazing to see Angel!
Pyrographers who traditionally draw pictures on flat board often apply light brush strokes with their heated instruments. Incredible effects can be created from various shades of burnt wood.
But they warn not to leave their art work exposed to direct sunlight as it can become bleached to a lighter color.

You have found a very interesting technique to turn negative pyrography into a positive effect. ;)

Cheers,
Mark

[Angel]

Yes maybe a technique for some background textures, or even some designs.
Of course I discovered it by coincidence, and the technique might be much refined. But at my approach, it insumes much time and control to avoid overexposition and possible cracks on bamboo.
The thing that I had already noticed is that some bamboo culms that I had torched some years before, become lighter in color compared with the new flamed ones. I thought several times if I had let them clear, or if they decolored by time and indirect UV exposition.

The net bag experiment realized that the color obtained in bamboo by flame torching it is somehow reversible, as any other dying technique.

It's possible other flamed bamboo apart from Phyllostachys species also decolor with time.
I use the heat tempering for much of my works, basically in different Phyllostachys, Pleioblastus and sometimes Bambusa species.
About bambusa, although I don't make controlled experiments yet, I think also that they decolore the flame obtained color with time.

[budoweapons]

I read some sort of the same info on preparing bamboo using a torch.
so i did it.
However mostly what I found was that torching it did nothing other than help me to remove the protective crystaline skin that it has on it and get alot of the dirt off from the exterior. I admit that it was a beautiful dark rich color when I finished but talk about a pain in the arse.

you would have to have a large oven to do what I think you want to do.
I don't have much experience, admittedly but the little bit that I do have requires that the bamboo simply sit outside and dry for along time.

I have a stand of huge green bamboo nearby and it took roughly six months for the stuff to change color- must not be doing something right!

Eddie

[Mark Meckes]

Hi Eddie,
I agree, it's a time culmsuming occupation though it becomes faster with practice. I only heat treat special pieces, small batches at a time. :)
Do you know the bamboo genus or species that you have to work with?

Heat treating can vary according to the culm wall thickness, (thick walled - slower heating : thin walled - faster heating)
... and degree of natural glossy or dull (more porous) 'skin' of the culm surface.
Flame torching green bamboo or dry bamboo are done for different reasons, producing different results.

I only torch dry bamboo as an alternate to using steel wool to remove the waxy film on the bamboo surface:

Heating/polishing dry bamboo with a propane torch
http://www.bamboocraft.net/workshop/data/518/medium/HeatMoso070411-6787.jpg (http://www.bamboocraft.net/workshop/showphoto.php?photo=1723) Large image (http://www.bamboocraft.net/workshop/showphoto.php?photo=1723&size=big&cat=518)

Top portion has been heated/ Bottom portion unheated
This piece of bamboo is Moso - Phyllostachys edulis AKA P. pubescens
The purpose is to melt/remove the white film of waxy coating on the surface of the bamboo, and to clean up and bring out the color of the bamboo. The bamboo gets hot to the touch but is not over heated.
The method I use is to heat the bamboo lightly with a propane gas torch until the waxy coating melts. When it is at a tacky stage I wipe off the exudate with a rag that I've applied paste wax to.
I use a carnuba based paste wax called TreWax though there are other paste waxes that will work.

Mark