Why we treat wood with Preservatives?
Heartwood is the portion of wood contains physically dead cells and it does not take active part in te life of tree. The time perios for the destruction of this portion significantly varies with different wood species. Based upon the service lie of this part, different wood species have grouped.
|Class I||Durable||Life 120 Months & above|
|Class II||Moderately Durable||Life 60 to 120 Months|
|Class III||Non - Durable||Less than 60 Months|
The class timbers such as Teak, dark Meranti, Shisham etc. does not require treatment with wood preservative chemicals but class II & Class III do require adequate protection against biological degradation and must be given treatment with suitable wood preserving chemicals before being put to use.
Treating Under Pressure
Impregnation of wood under pressure is the most desirable and best method to get uniform and proper treatment under controlled conditions. This is usually done in pressure cylinder equipped with vacuum pressure system, storage tanks and mixing tanks for preservative solutions.
Treating with Preservatives
An important aspect in impregnation of timber with preservatives is to get adequate penetration coupled with appropriate absorptions. Among the no. of processes impregnating the inorganic and toxic compounds in timber to make the wood material poisonous to fungus & insects is the most common practice. The treated wood is very clean and can be painted, polished, waxed. These are:
Copper Chrome Arsenic (CCA)
Copper Chrome Boric (CCB)
Acid Copper - Chrome (ACC)