Different types

Water-soluble salts are dissolved in water. On treatment, the water
evaporates leaving the salts inside the bamboo. These are further
categorized into non-fixing and fixing types.

These are leachable solutions and their use is restricted to bamboo used in
dry conditions and under cover. Bamboo treated with these preservatives
should not be exposed to rain or ground contact. Common example:
Boric acid: Borax & copper sulphate

These formulations are proportionate mixtures of different salts which
interact with each other in the presence of bamboo/wood and become
chemically fixed. In principle, the degree of fixation and efficacy depends
upon the nature of the components and their combination. For example,
Chromium is responsible for fixation, copper is effective against decay
fungi and soft rot and the third compound acts against insect and fungus.
The process of fixation requires some weeks during which the material
should be stored under cover. Slow fixation is preferred in case of bamboo
as it allows diffusion and better distribution of preserving salts.
Common example: Copper-Chrome-Boron, Arsenic Pentoxide & Boric
Acid

Coal tar and creosote available from coal is a dark brown viscous liquid.
Creosote should be used exclusively for pressure processes or hot and cold
treatment. Being oily, it imparts water repellence to the treated material. It
is effective against fungal and insect attack. Due to its dark brown colour
and bad odour, its use is restricted to exterior applications, especially in
contact with mud/ ground

These are slightly more expensive preservatives where the organic solvent
acts as a carrier for toxic molecules and later evaporates, leaving the active
ingredients behind. They are available commercially in ready-to-use
forms. A good formulation is an appropriate mixture of fungicides and
insecticides. There is little change of colour of the treated material but a
residual odour may remain for some time. The method of use will be
recommended by the manufacturer. Formulations available in
concentrates are more economical to use.
Common examples: Trichlorophenol (TCP) and Copper/Zinc
napthenates (metallic soaps) are used as fungicides. Lindane/
cypermethrin is used as an insecticide.

Some naturally occurring materials can prevent decay to some extent.
Long-term protection is not possible through these preservatives.
The Giant Indian Milkweed is deadly to beetles and fungi. Boiling of slivers
with fresh leaves and stem of this plant for 30-60 minutes will prevent
attack.