Heat treating for durability?

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ThatCompostGuy
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Heat treating for durability?

Post by ThatCompostGuy »

I've seen videos where someone will take a hand held blow torch and heat treat relatively green bamboo poles a little at a time until they turn brown and harden. If I were doing a lot of them at a time, would the same idea work with a larger fire, like a fire pit? Or does the heat have to be concentrated, like from a torch, to be effective? I've read about pressure inside causing explosions, so no need to explain about that.

Ideally, hardening would be for making furniture or other things for inside, out of the weather. But would hardening with fire help with weather durability as well? Or is there some other way to weather proof it so it lasts for more than a couple of seasons? Like for tomato stakes or other outdoor light duty structural things. Or patio furniture.

Is there a webpage I should be reading that I haven't found yet that would explain some of these common bamboo newbie questions I have? I don't want to grow it, just harvest relatively small amounts and use it non-commercially for myself.

Thank you.

Chris
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terrabamboo
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Re: Heat treating for durability?

Post by terrabamboo »

From what I've read, there are two objectives: remove the remaining sugars and moisture from within the outer skin, and remove the outer skin's powdery-white coating. Oven/kiln dried is more consistent from what I've read. Propane/torching is quicker, but sometimes unreliable when doing it by hand. When I get setup to do 1,000 poles/week, I will not be torching by hand! But I may invest in a long, 10' or 20' gas burner and basically "pig roast" my bamboo as an alternative to building (and paying electricity on!) a kiln.

When buying bamboo for your tests, make sure it is 4-5 year old bamboo -- I think people who have bad experiences just get young bamboo and don't know.

As far as weatherproofing what I have read: after wiping the "ooze" from torching the bamboo off apply some real wax ( http://www.amazon.com/Trewax-Paste-Wax- ... B005SRV1PI ) -- but care needs to be taken to protect the ends from water/insects long term if you want it outside.
Terra Bamboo
300 acre Bamboo Plantation Project
Focusing on Henon, Moso, Robert Young, Rubro, Vivax and Fargesia
ThatCompostGuy
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Location: Clemson, SC

Re: Heat treating for durability?

Post by ThatCompostGuy »

Buying bamboo??? :-) I'll be cutting my own from local sources or scavenging it after it has been cut, depending on where it is I get it. I'm close enough to the famed Anderson Moso grove that that's where I'll be getting some in the spring. I talked to someone last week and he said there may be 300 or 400 poles a year that they end up disposing of because people don't want them. So I'm going to call in April and get to know the folks that maintain the cemetery. :-) I went by and looked it over last week. I don't see what the fuss is all about other than the size potential.

I have a friend at work that has smaller wild bamboo growing in her yard that says I can have all I want, so I'll be taking more there next year as well. Smaller diameter. 2 to 3 inch at most. But nice and tall. 30 feet or better.

And there are other groves scattered about close by that I can raid for the wild bamboo. I won't be buying anything. Just time and fuel to collect.

I've been reading about tempering and heat treating today. I think I have found the info I was looking for.

Thanks again. Let this topic die off.
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terrabamboo
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Re: Heat treating for durability?

Post by terrabamboo »

I only assumed you were buying as you mentioned you do not grow it.

Anyways, please share what you find here with links, pdfs, etc. It will be a great tool when others search for the same topic. It comes up quite often.
Terra Bamboo
300 acre Bamboo Plantation Project
Focusing on Henon, Moso, Robert Young, Rubro, Vivax and Fargesia
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terrabamboo
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Re: Heat treating for durability?

Post by terrabamboo »

just following up here with my own research in inbar's pdfs...
The superior tensile strength of bamboo in
relation to wood and steel is demonstrated by
the following comparison: a steel bow of a
certain quality (SA 37) of 1 cm2 with 1 m
length has a weight of 0.785 kg and a
ultimate tensile force of ca. 40 kH; a stick
from wood with the same length and weight
would have a cross section of 13.5 cm2 and a
breaking point at 80 kN, but one from bamboo
with 12 cm2 would resist up to 240 kN;
e.g. six times that of steel. The moisture content
has a similar infIuence on the strength as
it has in timber. Generally in the dry condition
the strength is higher than in the green condition.

This increase in strength with seasoning
is more obvious for younger culms than for
older ones. The differences between the air
dry and green condition are sometimes
relatively small, especially for bending and
cleavage (cf. Table 3) (Ota, 1953).
Terra Bamboo
300 acre Bamboo Plantation Project
Focusing on Henon, Moso, Robert Young, Rubro, Vivax and Fargesia
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