How to treat bamboo stalks?

Hi,

The bamboos I planted 20 years ago have grown into a sizable bamboo grove and I have enough bamboo stalks for construction. The problem I have is that bamboo is not normally grown in my region and there is no experience in how to treat the bamboo stalks to protect them from the weather, fungi and worms.

I have different types of bamboo, some are good for eating others are good for construction, but most deteriorate after cutting. Most develop different types of fungi (mostly green and black fungi) and some have worm-holes. Most also split after exposure to the sun.

Is there any way of treating the stalks that doesn't require expensive equipment?

Cheers,
Dieter

I love your bamboo Dieter!
I haven’t dared plant any here yet since I gather they’re not fond of wind....but I won’t be able to resist for much longer.
You don’t say where you’re based, but I gather from your other posts that you have a pretty dry climate, with rain during the cold season. Is it possible that the bamboo is not properly ripe for you? They grow just in one year don’t they, like a grass? Perhaps they need a bit more drying out to cure them somehow?

I'm a total amateur, but some of the things I've read and done:
1. When I cut them, I leave the leaves on and lay them against the fence in the shade to gradually dry - my understanding is that as the plant tries to keep the leaves alive, it uses up a lot of the sugars that would make them attractive to bugs.
2. I try to be organized enough to mark the culms in the spring. My reading suggests that harvesting culms at 5 years of age is best for strength and longevity.
3. The year my grove got a lot of poopy water from the ducks stock tank, it put out a *lot* of large culms, that were very weak compared to the years when they survived on minimal extra water. If I get the duck area set up properly, my goal will be to give the grove a little duck water but more like once every 2-3 weeks rather than every 3 days!
4. I have read that often bamboo is soaked in a mixture of boric acid and borax (subtly different forms of the same chemicals) Borax discourages bugs. However, figuring out how to do so on my scale in an environmentally sound way has discouraged me from trying. If I was building more than a garden trellis, I might revisit it!

Jay Angler wrote:4. I have read that often bamboo is soaked in a mixture of boric acid and borax (subtly different forms of the same chemicals) Borax discourages bugs.

Nailed it.

Best way is split the culms and make a 'soaking tub' and submerge.  It can be a pit lined with plastic.  Weight the bamboo so it is completely covered to get all parts soaked.  Let sun dry.

A different but less effective way would be to use a Ag sprayer and saturate thoroughly.  Soaking is the best option though.  

If you are looking to use full rounds then remember to puncture the inner segments at the nodes.  Bamboo is not hollow through out.  There is a thin wall the forms between each 'joint' in the culm.  To get the solution through the full length, a rod is driven through end to end to puncture the nodes.

I had grown a grove of big bamboo kind of like what's in your picture on my little 80'x120' lot of my previous house. it grew taller than telephone pole and 4- 5 inch diameter at the base, once new sprouts would come up in wet season some grew as much as a few feet a day or more. awesome stuff. super strong even when dried naturally and split, still much stronger than any lumber of the same size. be fore I moved I wanted to cut it all down and take it with me to build something with but that never happened and I didn't have 50' trailer and I only have a few pieces that are less than 8' long for some yet undetermined project.
yes and boric acid will kill fungus, bacteria, mold and bugs, mixed with peroxide it preserves wood type products very well. I'm not sure its necessary for dried bamboo but there are an awful lot of different varieties of bamboo and I sure aint no expert. as far as the wind I had several good size groves of three different types of bamboo and they all survived every hurricane and monsoon season. all grown in. very loose sandy soil.

Bamboo are okay in the wind, they are from the tropics with hurricane/typhoons.

Bamboo is usually treated by soaking them, mostly to get all of the sugars out of them.  You can soak them in:
1) borax+ water solution
2) just regular seawater/saltwater
3) even just regular river/fresh water.

here's some I grew

Nancy Reading wrote:I love your bamboo Dieter!
I haven’t dared plant any here yet since I gather they’re not fond of wind....but I won’t be able to resist for much longer.
You don’t say where you’re based, but I gather from your other posts that you have a pretty dry climate, with rain during the cold season. Is it possible that the bamboo is not properly ripe for you? They grow just in one year don’t they, like a grass? Perhaps they need a bit more drying out to cure them somehow?

Hi Nancy,

I don't think that is the problem. It's true that new stalks grow every year; however, one has to wait at least 4 years before harvesting so they are hard enough. I mostly harvest after 5 or more years.

What I understand is that the stalks need to be treated by heat treatment or some sort of anti-fungal paint, etc., to protect them.

It is said that bamboo doesn't like wind; however, that doesn't mean that it won't grow at all. Just try and find a good place for the bamboo. Some types of bamboo can also be trimmed into hedges to serve as windbreak. I can check which types are suitable, if you are interested.

Cheers,
Dieter

Dieter said

I can check which types are suitable, if you are interested.

Oh yes (although it’s hi-jacking the thread a bit). I’ll start a new topic.

Jack Edmondson wrote:

Jay Angler wrote:4. I have read that often bamboo is soaked in a mixture of boric acid and borax (subtly different forms of the same chemicals) Borax discourages bugs.

Nailed it.

Best way is split the culms and make a 'soaking tub' and submerge.  It can be a pit lined with plastic.  Weight the bamboo so it is completely covered to get all parts soaked.  Let sun dry.

A different but less effective way would be to use a Ag sprayer and saturate thoroughly.  Soaking is the best option though.  

If you are looking to use full rounds then remember to puncture the inner segments at the nodes.  Bamboo is not hollow through out.  There is a thin wall the forms between each 'joint' in the culm.  To get the solution through the full length, a rod is driven through end to end to puncture the nodes.

That's what I have been planning on doing. I already got a 10 kg bucket of Borax. Diluted, that should give me a few hundred liters of solution; however, still not an awful lot if I want to soak 5 meter (about 16 feet) bamboo poles.

I'm also reluctant to build such a long vessel for soaking. I guess lining a depression in the soil with plastic may do; however, it's kind of messy if I want to reuse the solution. I don't think I'll be able to soak all the culms at one time. So I'm planning on filling the solution in containers to reuse it again.

One other idea I have thought about is to puncture the separation nodes inside the culms, and then close one end of the culm with a plug and fill the solution from the other end. After letting it soak for a while I could pull the plug to empty the solution into a container for reuse.

I think the solution penetrates the culms best from the inside because the outside is so smooth that it repels liquid.

What do you think?

I also heard that Borax is against bucks but not against fungi. Does somebody have information on this?

Cheers,
Dieter

I'm in wet tropical rainforest 1.3 to 4.5 metres of rain since I've been here.
The big green bamboo will probably last 2-3 years indoors and outdoors much the same if old culms are left for the leaves to use up the sap -thats all I'm doing.
I've been using the gold and green bamboo, mature culms,because its easy and close and left it for the leaves to use up the sap (mostly).
Outcome from being casual, any out in the rain lasts one year. Under cover 2-3.
Not what I'd call sustainable but its based on how far and how heavy a cut piece is I have to carry up the hill.

If I was more serious I would leave it in the spring fed stream for 3? months. Its a long drag and back uphill but worth it for a long term project.

When I lived in India all our important bamboo was submerged in salty water for the monsoon - that kept the bugs out.

Yes there is a very sustainable cheap way very ancient cultures have treated bamboo. Make a small fire and pass the bamboo culms across the flame gently. This changes the chemical structure of the resin and causes it to rise to coat its own surface into a preservative. It also gives the bamboo a beautiful dark glassy shiny color and a slippery water resistant surface. The texture completely changes.  I have done this and it works beautifully.  It is done while still green and sappy any time of year. I think maybe a gas torch might work but maybe it would be way too hot? A flame is what everyone has always used. It takes time but a skilled bamboo craftsman enjoys that.

I've used borax and boric acid many times as a pesticide mostly against mold and rot on wood and other building materials like drywall. It works well for insects like termites and ants too, and it even makes the wood fire retardant. But it leaches out if the stuff gets too wet, so it won't last long out in the rain....so it's not much good for outdoor uses like fence posts.  For bamboo, I learned years ago at a workshop that you want to cut stalks at least three years old....these are fully mature.  With many species you can distinguish the older canes because the ring of wax just under each node will turn from white to black.  After harvest, it's then recommended to leach the bamboo for a month or more under water, preferably running water.  For whole canes this can be done by tying them together in bundles and then making a raft of them, and then pile heavy things on the raft so that it is held just under the surface.  If you want split bamboo, it's easier to split it green, and then bundle the splits and leach them....split bamboo will often sink of itself; or will need a lot less weight to hold it under.  Then after the leaching, pull it out and let it dry slowly in the shade.  The water supposedly leaches out the starch and sugars in the fibers, which are the main attractant to insects.  Drying slowly helps the bamboo cure with minimal cracking....which is desirable for whole canes for building purposes.   There are all kinds of exotic treatments to be read about out there....some involve cutting the bamboo, and leaving it in the grove, held up by the surrounding bamboo, and then right away standing the cut ends in a bucket of preservative, so that the transpiration of the green top will suck the solution up through the fibers....this however would leave the bamboo unleached and full of sugars etc.  An even more intensive design I saw involved welding several metal barrels together end to end, without the ends on the center ones, so as to create a long metal tube that could be sealed with a removable lid.  Bamboo canes are loaded into this, bottom ends all toward one end, and a small amount of water added.  The whole thing is then stood up and a fire kept going under the bottom end.  Supposedly the water boils and forces it's way up through the channels in the bamboo and then condenses back down, which dissolves the sugars, melts the waxes, and alters everything such that the stuff is preserved in it's own juices.  After a few hours of this it's left to cool and taken out.  Recalling it makes me interested to read about it again and see if it's myth or fact...has anyone else ever heard of this?

Yes you are very right, it is very important to make certain the bamboo stalks are fully mature. At least old enough to have lived a full summer and overwintered before cutting them down or they will be too tender. Three years is best if you want strong timber.  Overwintered after a year is bare minimum for projects like weaving or furniture but still too weak. Very good to point that important fact.