Notes to broadcasters
Content: Bamboo structures will last longer if they are protected from the things that weaken them. Dampness and the larvae of the powder-post beetles are the main enemies of bamboo. Clump-curing or soaking under water help remove the starch from the bamboo stalk, and starch is what the beetle larvae are after. If the bamboo is to be in contact with damp soil, protect it from rotting by painting it with used motor oil, or by setting it on stones.
Today, let’s look at some ways people preserve bamboo so that the things they build with it will last longer.
The greatest enemy of the bamboo plant is the powder-post beetle. The larvae of this beetle like starch, and bamboo contains a lot of starch. So the key to preserving bamboo is to remove as much starch as possible.
There’s a simple way to remove starch from bamboo. It’s called the clump-cured method. Here’s how it works.
There’s a special time to cut the bamboo tree. It should be cut at the time of year when there’s the least amount of sap in the wood. For example, in the Philippines, bamboo is cut in the dry season. In Sri Lanka, some farmers cut it during the waning phase of the moon.
Cut the bamboo stems close to the ground, but don’t let the stems fall to the ground, and don’t cut off any of the branches or leaves. Let the stalks stand in the bamboo grove. If you leave some bamboo trees standing, you could tie the cut stems to them to stop them from falling to the ground. Some people just prop up the stems with long stakes. If the trees you cut are left standing in this way, the leaves and branches will continue to suck the starch from the stalk for nourishment. Leave the stalks standing and drying out like this for four to eight weeks. Then they’ll be ready to use for building.
Here’s another method of removing the starch from bamboo to preserve it. This method is very popular in Indonesia and Thailand.
Take the freshly-cut green stems of the bamboo plant and submerge them completely in water. Fast-running water is best because slow-moving water or muddy water can stain the bamboo. You’ll have to tie rocks to the bamboo to keep it securely weighted under water. Leave the bamboo to soak for two to four weeks, but no longer than four weeks. In this time, a great deal of the starch is removed from the bamboo. If you want to preserve split bamboo, you can split it before soaking. Split bamboo will lose its starch a bit faster when it’s being soaked, because more of the bamboo’s core will be exposed to the water.
It’s important not to leave the bamboo soaking for more than four weeks. If you do, the bamboo could be damaged. It can become brittle when it dries out, and it won’t be suitable for building material.
After soaking the bamboo, let it dry naturally for several weeks—until it’s dry enough that you can cut through it with a saw.
Beetles are not the only enemy of bamboo. Dampness will cause it to rot. So protect bamboo from the damp soil when you build. One way to do this is to paint the bottoms of your bamboo posts with used motor oil before you place them in the ground. Also, try placing bamboo stalks on stones instead of putting them directly onto the ground. This helps keep them dry, which will help protect the bamboo from rotting.
One final thought. In Angola, bamboo is sometimes used along with iron rods to reinforce cement slabs. All that’s necessary to prevent it from rotting inside the cement is to char the outside of the pieces of bamboo in the flames of a good, hot fire.
Used motor oil also protects other kinds of wood from termites. You may want to use this item with:
Wood preservation costing little or no money – Package 13, Item 9
1. The Book of Bamboo, (1984, 332 pages), by David Farelly, published by Sierra Club Books, San Francisco, California. https://archive.org/details/TheBookOfBambooPart1-DavidFarrelly/page/n1
2. Dr. Allen T. Knight, FAIC, Technical Consultant to DCFRN, an agriculturalist who worked in Angola and Zaire for 34 years.