View Full Version : Oven-heat tempering bamboo
14th February 2005, 09:39 PM
It may seem a little crazy, but instead of heat tempering the drumsticks with a torch, I put them in the oven! My wife thinks I'm totally 'gone'!
15 minutes at 350F and they get extremely hot and nicely browned(inside too!) for the sanding and tung oil.
Any opinions/thoughts on this technique?
best regards to all!
The Drumstick Guy
16th February 2005, 07:11 PM
Can you send us pics of your experience?
16th February 2005, 10:40 PM
Cant' send photos yet. Will do when we have a presentable product. What I can say for now is the bamboo comes out of the oven very hot and steaming.
This, for what I have read so far seems to be enough to melt the sugars and starches in the bamboo.
I also tried one pair on 'broil' with the grill set lower! Even faster 'cooking' and hotter. Just watch they don't burn!
After preparing the bamboo, it looks GREAT with tung oil.
Will keep everyone posted!
18th February 2005, 09:44 PM
Sounds great, but how do they taste?
24th February 2005, 06:07 PM
I had some experience with bamboo and ovens, but, What kind of oven are you using?
24th February 2005, 09:34 PM
We have used two techiques for the heat tempering. The oven we use happens to be in our KITCHEN! The same one my wife uses for roast beef.... :eek:
It's ok but there seem to be more problems with the bamboo warping using this technique.
About 15 minutes at 350F is about right. But, the bamboo is warping.
Not good for drummers.
We seem to have better results with a propane torch. Just need to be very careful not to burn too much!...keep the torch moving constantly.
We'll experiment a little more with the propane torch technique. If they still bend too much, we'll simply produce the sticks senza la quemada and with PLENTY of tung oil!
I have played concerts in your country many years ago...Rio and Sao Paulo---beautiful!
The Stick Guy
27th March 2005, 02:38 AM
Most of my oven baked bamboo experiments (electric heat), has been using bamboo in the green or partially dried stages. I have not tried this with dried bamboo.
With green bamboo the fiber alignment is not as `fixed' , as with dried bamboo. Because of this, removing too much moisture too fast creates more stress, and excessive heat and duration of baking can cause cracks, splitting.
I never heated the oven to more then 250- 350 degrees F . This is a guess because I do not trust the accuracy of my temperature gauge.
Results vary if using the top shelf or bottom shelf in the (electric) oven - more likelyhood of scorching on the bottom shelf near the heating elements.
My experiments would sometimes take place after dinner was baked , taking advantage of an already hot oven. If the food was cooked at 450 o F, I would sometimes put the bamboo pieces in right away, turn the oven temp down to 250, keeping an eye on the bamboo, taking them out and wiping the wax off as soon as the surface became slick.
(side results - dinner gets postponed - cold food)
So there is a difference with heating the bamboo up gradually when turning on the oven, or in starting off with a hot oven.
I like the `extra working time' that the moisture content of green bamboo provides, and the richer brown, rather then charred black color dry bamboo produces. (especially with flame torching method)
The objective is to only remove minimal moisture, and let the rest dry naturally, within a month or so, depending on the time of the year, heat/air circulation and humidity.
Well, not everybody can have green or partially dried bamboo at their finger tips, and whenever I harvest green bamboo I know I only have 1-3 months before it changes it's characteristics.
So the question is... what is the purpose of heating the bamboo?
... to sterilize, to colorize and caramelize, to plasticize and realign the fibers, to stabilize and make the bamboo more crack and warp resistant upon cooling and curing...
The results vary depending the type of bamboo, it's skin/surface consistency and culm wall thickness ... whether is green or dried, the type of heat, duration and intensity.
... to melt the grey surface wax to clean and provide a brighter lustre.
... to carbonize the surface and change the color of the bamboo, to flame texturize.
... to thoroughly bake and completely carbonize the bamboo.
An interesting area to learn about oven baking is from the bamboo flooring manufacturing industry and also from bamboo flyrod fishing pole making.
I did a bit of searching on making fly rod poles and oven baking, and the opinions seems to vary a lot, with temperatures ranging from 220 up to 375 degrees F). Techniques and procedure varied a lot.
16th April 2005, 01:39 PM
Is there a rough guide on temperature and time spent in the oven and how thick/green the bamboo is? Or is it more general? I could try a low temperature and a long cook-time, checking it every... ten minutes or so?
I have 4-inch diameter timber bamboo, very green, and this sounds like something I could do, not having a torch.
17th April 2005, 06:21 AM
I think it's important to differentiate between the process of heat tempering green bamboo, which may involve an initial dose of heat, without extracting a large amount of moisture, then allowing the bamboo to air dry naturally, versus kiln drying bamboo, as is done with timber, where heat is employed over a longer period to reduce/extract the moisture from the wood down to a small percent.
I don't believe `kiln dried' bamboo bamboo has been discussed here at the forums yet.
I can only give you a rough guestimate of how I flash cured /heat tempered green bamboo in the oven. I've never timed myself, I usually have several pieces in the oven at the same time, (and my wife says I work myself into a frenzy, juggling between the different pieces in the oven)
Heat 250 - 300 o F
Have gloves and wiping rag handy, bees wax or paste wax.
I don't like to leave the bamboo in the oven any longer then necessary, maybe 10+ minutes, only to remove minimal moisture, or bamboo may warp and crack, especially bamboo in the round... Check oven / bamboo occasionally, when surface wax changes from sticky to slick, take out, rub on some beeswax or paste wax (I like `TreWax'), and wipe off excess residue. Surface color will change to green/tan.
Depending on the results you may want to put back into oven for a few more minutes.
Let cool and air dry for several weeks or so for rest of moisture in bamboo to be released.
Let us know how you do. I have some big boo and I'll try it again soon and will take pics.
Also see post #5 which I just posted in the thread - `Flame torching' bamboo (http://www.bamboocraft.net/forums/showthread.php?t=938)
...which discusses different rates of contraction of bamboo during drying of a (gas) flame torched piece of green bamboo.
In a way the principle behind the process I have just explained is similar in that I only wish to temper the bamboo, to primarily make it more resistant to cracking. I'm not trying to kiln-dry the bamboo.
20th April 2005, 07:47 AM
For over a month I have searched, begged, cajoled and generally made a pest of myself trying to find a method of speed curing Bamboo for use in flute making.
A fellow who is a member of a fly rod makers group had an oven which he used to dry a section of Bamboo. He used 225 to 250 degree heat for a period of 67 hours. The section came out with discolorization, maybe not a big deal, and slightly curved, possibly more of a big deal for drum sticks.
Shortly after he did that experiment I was all set to build a small kiln/oven for the purpose of quickly curing Bamboo for flute making, until I got a few emails saying that during the natural curing process large cell formation took place inside the Bamboo. Those large cells enhanced resonance and tone. When heat was applied in an oven or with a flame, the formation of large cells was stopped.
It is logical to me that smaller sized cells "might" be better for drumsticks because the sticks would be more dense, therefore more solid.
20th April 2005, 08:21 AM
Oh yes, I studied kiln drying too. With lumber the temperature is set at about 100 degrees F and the time is still not much shorter than air drying. Air circulation was a big factor for the kiln as was keeping humidity at the right percentage.
The fellow I mentioned in the previous post remarked that the varnish on the outside couldn't be removed with a light washing. I was sorry that I didn't mention to him before he started the project that the sticky stuff should be removed with a rag 2 or 3 times during the process. He also mentioned that after he had the oven going for several hours he increased the temperature from 225 deg to 250 deg F and that he believed he should have left it set at 225 deg.
I think that possibly a slightly lower temperature should be used to prevent the slight warp he had.
The 67 hour time period is longer than we want to have the kitchen oven tied up. I was thinking of making a wood frame oven, insulating between the wallls and using light bulbs for heating. Several years ago I used wafer type thermostats to regulate hatching incubators while raising quail. I don't know if they would regulate at 200 deg, but at around 100 deg they regulated the temperature within 1 degree consistantly.
24th April 2005, 09:09 AM
Bamboozle wrote... during the natural curing process large cell formation took place inside the Bamboo. Those large cells enhanced resonance and tone. When heat was applied in an oven or with a flame, the formation of large cells was stopped...
hmmm... now, who do I know who might have a microscope that I can take cross-sectional samples of bamboo of various heat treating experiments vs natural drying techniques and have a look-see of what happens to those bamboo cells? How much X magnification would be required to determine the differences?
Re: kiln drying, I remember reading an excellent article which I have somewhere but can't find at the moment, about kiln-drying lumber which stated the importance on initial stages of drying, (using heat and air circulation in an enclosed chamber), to regulate, ie keep the humidity level high, releasing the moisture from the enclosure very gradually to prevent warping.
26th April 2005, 08:13 AM
I'll restate that MY puropse for wanting to speed up the process is/was to beat a deadline for a craft show. My particular use the Boo is for making musical flutes. For other purposes the large cell, small cell phenomenon may not matter.
I have learned recently that the large cell formation is not stopped unless the water inside the Bamboo is raised to a temperature that makes it boil and come steaming out of the ends of the section. If my information is correct and if the culm sections are heated to only 150F to 175F the large cell formation isn't hampered.
A microscope intended for looking at germs, I think, would be the wrong type of microscope. That is unless you use a microtome to cut the boo into extremely thin slices. There is at least one other type of microscope, those used for lab dissecting, which I think would be more appropriate for the use you stated above. Those allow the subject under observation to be further from the lens and are easier to find the area for study. I believe that about 40x would be enough mangification.
I have no experience with a microscope so I stand ready to be corrected by those who do have it.
7th June 2006, 11:15 PM
I had recently asked you some questions and received great answers.
Now I tried some things you have not covered or I have not found in forum, I tried the drying by fire which was not to my liking as I tended to scorch some....
So I put some very green shoots in my electric oven at 300 degrees.... after about 6 hours I had very shiny and almost mahogany colored bamboo....
love the effect....
This was just a fluke but have you ever tried it or is it going to cause me problems with the strength of the bamboo?
None of mine warped and I did not have to wipe or rub the bamboo. The color was really great.
8th June 2006, 07:13 PM
Thanks for sharing your experiment with us!
The best way to learn is with an open mind, and often those who are new to bamboo have the best minds for experimenting and discovering new methods.
I have never tried heating green bamboo at this temperature for this length of time.
when you say ... "I put some very green shoots in my electric oven at 300 degrees"
Are they younger culms from your fortunate harvest?
Reference thread: Bountiful harvest (P. aurea) - some questions (http://www.bamboocraft.net/forums/showthread.php?t=1894)
Is the oven treated bamboo completely dried now?
An interesting experiment is to weigh the bamboo before and after oven treating.
Do you have a camera so that you can show pics?
BTW, Summer has arrived a month early here in Texas, and with temperatures hovering around 100F and no rain, it's like living in an oven.
8th June 2006, 07:47 PM
All the bamboo was green to some degree, the pieces that turned the darkest
had been cut 3 days ago. I tried to down load pic and it said I had but now I lost it, (is it cause I am a blond?) Ok tried again said it is attached sooooo
I will send and see what happens.
8th June 2006, 08:17 PM
This reminds me of a craft article from years ago, of someone who baked pumpkins or squash in an oven till they became rock hard and crafted jewelry boxes out of them. The then Prez, Jimmy Carter was the recipient of one of them.
10th June 2006, 02:27 PM
Is there a reason the greenest turn the darkest? Due to rapid drying and removal of a larger amount of moisture? The dryer the piece was when I put it in the oven the lighter it stayed.
10th June 2006, 05:10 PM
I will hypothesize ... v : to believe especially on uncertain or tentative grounds ... that the 'succulent sugars' in the greener culms have caramelized more readily from the heat treatment.
11th June 2006, 03:08 PM
If I do not fry my poor brain from the heat will let you know how futher tests prove out.
We are so hot and dry here it is unreal, course you understand you are in
texas, but we have seen a slight rain in the last 3 weeks. Too hot to think;)
12th June 2006, 02:29 AM
Yes, I agree, I think I'll wait till cooler winter weather before trying out your lengthy oven experiment.
Texas has become an oven, in fact, as I was leaning on a sunbaked bamboo culm growing in our grove I was surprised how hot it was to touch!
13th June 2006, 11:04 AM
In this heat treatment the one thing I did not think about...my oven is one of the newer ones you can lock and it will self clean.
It has really good seals so as the boo bakes a lot of the moisture stay in the oven with it. This may have some thing to do with my results may not but it is something to think about. My oven does not even heat up the kitchen so most of the heat stays in....
14th June 2006, 09:21 PM
I put boo that was dry dry in the oven at 300 along with some other pieces..... left it for 10 hours and now all of it darkened and shiny?
I know not what I am doing but love the results.:confused:
16th June 2006, 07:00 AM
Hi Linda, you are quite right about the type of oven ...
Ours is quite old, is not seal-tight and I don't trust accuracy of the temperature dial, so recently got a new oven thermometer to stick in the oven when I'm ready to experiment again.
It's been sooo hot here ... we had 100 degrees F - an all-time record - in April and it's stayed hot since ... and summer hasn't even officially started, so I'm avoiding the oven.
... and enjoying hearing of your experiements - from a distance. ;)
Do show pics when you can..
Some things I've noticed regarding culm age and heating ...
Very young culms will develop more 'groovy' ridges on the surface when heated. ie greater shrinkage
Young to medium age green bamboo that is heat tempered can sometimes become more resistant to cracking afterwards.
... not a blanket statement ...
Old dried culms can be more susceptible to later cracking.
Just like people ... the older you get, the easier it is to fall apart.
Here's a post about cause of splitting (http://www.bamboocraft.net/forums/showpost.php?p=1225&postcount=3) ...
18th June 2006, 10:24 AM
These are pics at 11 am and then after 6 hours at 300 degrees.
the line-up and pieces are exactly the same....
:p We are getting rain and it is a lot cooler;)
(I live outside shreveport-bossier)
13th July 2006, 10:59 PM
I replied to your PM question with another PM then decided to log on.
I've been making flutes with Bamboo/cane for a couple of years and in the meantime learned the way to treat it properly for use in making flutes.
From what I've learned about heat treating, using an oven or a kiln won't relieve enough of the internal stresses to keep it from splitting eventually. That may slow it down, but incomplete stress relieving will allow the medium to crack within a couple of years.
Actually, I'm not certain absolutely that it will apply to craft work other than flutes. Kiln drying is used for construction of homes, but if memory of my research is correct the homes need to be rebuilt periodically because of deteroriation of the material. The difference would mainly be that flutes are exposed to moisture in the form of condensation, while being played. This is exaggerated during cold weather. I can see why the material doesn't last for houses that are exposed to rainy environments even after kiln drying.
Basically, for flutes, use a propane torch to blacken the surface of the culm section, set it aside for 6 to 8 months and repeat the process. There's a test to perform (immediately after the second flame treatment) that will tell whether the stress is removed entirely with the second flame treatment or if there should be an additional treatment. As soon as the test shows positive that the stress is gone the tube is ready to be made into a flute.
If you, or others, want elaboration, detailed information can be found at a native flute making forum.
is the link.
When you get there click on "Files" in the left hand column. When that page opens scroll down to files with keywords pertaining to bamboo harvesting, heat treating, flame treating, preservation, preparation and other keywords that seem logically to apply. The author, pioneer and perfector of the process is James Gilliland. Jim has been making flutes with the medium for over 18 years and is considered a knowlwgable authority on the process of heat treating and flute making flutes with cane/bamboo. Jim has won several prestigious awards for his flute making and has made Native American flutes for movie companies.