How To Treat Bamboo With A Borax

It’s difficult to find a more sustainable and durable building material than bamboo. It has been the go-to material for large and small construction projects in Asia for centuries. Moso bamboo (Phyllostachys edulis) is the most popular lumber species.Bamboo is a very hardy plant with natural pest and disease resistance. Also, Bamboo contains a large amount of starch and some sugar in it which attracts fungi, mold, termites and powder-post beetles etc. Therefore, bamboo gets easily attacked by little black bugs (the bukbuk), termites and fungus if not treated. So it needs to be treated in order to increase its longevity and to protect the bamboos from insects before it is used for manufacturing furniture, handicrafts etc.

An untreated bamboo is considered durable for 2 years if stored and preserved from moisture and insects it may last 4-6 years. Though actual longevity may vary depending on the species, thickness, length etc, if treated properly a bamboo or its furniture may last up to many decades.

Why is the treatment of bamboo required

Bamboo treatment and preservation offers an opportunity to help:

  • prevent over harvesting of bamboo and create sustainable bamboo utilization;
  • preserve traditional building techniques;
  • offer durable bamboo housing and products; and
  • encourage the production of bamboo handicrafts and other marketable products.

Treatability of Bamboo

Bamboos are anatomically different from both hardwoods and softwoods in their mode of growth and tissue organization. The tissue of bamboos is built up of parenchymatous cells and vascular bundles (vessels and thickwalled fibres). The vascular bundles are not uniformly distributed inside the culm. Numerous smaller ones are 49 present towards the outer portion while larger but fewer bundles are found towards the central part of the culm. Bamboo has no radial cell elements like the rays in wood. The outer wall is covered by a thin and hard layer and is less permeable than the inner layer. Due to these differences in anatomical structure, bamboo behaves entirely differently from wood during treatment with preservative.

The vascular bundles play an important role in preservative treatment. The axial flow is quite rapid in green bamboos, because of the end to end alignment of vessels. The degree of penetration decreases as the distance from the conducting vessel increases. The larger vessels (metaxylem) tend to get a larger amount of preservative than the smaller vessels (protoxylem). Although the anatomical structure of some bamboos has been well studied, there are not many studies on the flow channels and distribution and location of the preservative chemicals in the different structural parts. Recently, a study was conducted in Dendrocalanms strictus using organic and inorganic chemicals to determine the flow paths. The penetration results showed that creosote was better distributed than water soluble inorganic chemicals

What is Treatment:

Bamboo treatment is a process in which the starch, sugar, and moisture contents of bamboo are administered/removed thus making it resistant to termite, fungus & bugs.

There are various methods in which bamboo has been treated for years now, Traditional methods which include torching, smoking, curing, whitewashing and more modern methods which treat bamboo using various chemicals. There are various methods for treating a bamboo. Choice of those methods would depend on various factors like:,

  1.    whether the bamboo is green or dry. 
  2.    whether Short term or Long term Protection is required.
  3.    whether it is a round bamboo or in splits or in pieces.
  4.    Is it going to be used outdoors or indoors
  5.    Is it going to be used for structural purposes /Furniture / Handicrafts etc?
  6.    The scale of Operations (A method might be viable only for small-scale/large scale operations)
  7.    Availability of resources (machinery, chemicals, time etc.)

The use of the non toxic Borax and Boric Acid solution has been proved to be effective in the treatment of bamboo against bugs and insects. The treatment is a Prophylactic Treatment which resisted the attack of borers but was not as effective against stain fungi.

Treatment methods

Harvest typhoon blown clusters of Giant Bamboo that is perfect for house construction and furniture making. Cut 30 pieces of Giant Bamboo in 17 feet (5 meters) long poles, which are when fresh, are quite very heavy.
The Bamboo should be treated within 24 hours after cutting to avoid the little happy bugs drill themselves deep inside.
Dilute 12.5 kg Boric Acid and 15 kg of borax in 200 liters of water. A higher concentration (20 kg boric acid and 20 kg borax) in the solution might be more effective. Open the inner segments with a 20 feet long steel bar with 10 mm diameter. The last segment at the bottom should not be opened so that it will contain the solution, like in a tall glass.
After that, position the bamboos standing in a drum containing 30 to 40 liters of solution; fill each and every pole completely with the solution.
After 7 to 10 days, the bamboos have to be lifted straight up for the breakage of the last segment to release the fluid.

The soaking time depends on the size of the stalks. Small stalks suitable for furniture need to remain in solution for about one week. Larger stalks should remain about two weeks. If you stand the bamboo in a bucket or drum, you’ll probably need to top off the boron solution as the stalks soak it up.

After soaking, remove the bamboo and stand it upright leaning against a building or fence in a sheltered location to allow the water will to drain to the bottom of the stalks and into the ground. Neither borax nor boric acid are toxic enough to harm the soil. You can also catch the drainage in a pan and reuse it. Drying time depends on humidity and sun exposure.

Then store the bamboos for drying in a dry and good ventilated and protected place.
After 3 to 6 weeks of drying, they can be used indoor or outdoor, for construction, furniture and maybe for decoration as well.

Treating bamboo for use in outdoor construction projects is a bit more complex. The chemicals used, such as copper chrome arsenic (CCA), aren’t recommended for household use and need to be applied under pressure to be effective. You can also coat the bamboo by spraying or brushing with creosote to render it suitable for ground contact.

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