RETENSION

Retention: The amount of preservative solution absorbed in the wood after the chemical treatment. It is expressed in kg/m3.

PRODUCT DESCRIPTION
LB is new generation poly boron based cold water-soluble wood preservative for the protection of timber against insects, fungi, termites and borer. It is also compatible with the adhesives/ glues used in the plywood/block board etc. It is free from arsenic and chromium compounds and is thus nontoxic to human beings.

Methodology:
1. We took a sample each from two lots of timber of two different species to be treated and marked them.
2. After that we took the initial weight of the samples.
3. Then calculated the volume of the samples.
4. These samples were then kept inside the preservation chamber and full cell method of treatment was followed, chemical used for treatment was LB chemical.
5. After completion of process, the final weight was taken.
6. Retention is calculated by following formula:



Retention of the preservative chemical = 𝐆𝐂𝐱 𝟏𝟎 = kg/m3
𝐕


Were,
G =Difference between the weights, before and after treatment (g) C = Concentration of preservative
V = Volume of wood in cm3

Concentration of preservative used:
Treating Solution = 1000 Liter of Water + 20 kg of chemical.
= 2%


Procedure:

• Full cell method is followed in which initial vacuum of 120 to 130 mm of Hg is applied for 30 minutes.
• After removal of vacuum, the tank is filled with preservative and a pressure of 95-110 psi (Fig 2) is given for about 2 hours 30 minutes.
• After then, the pressure is removed and a final vacuum of 120-130 mm of Hg is given for 10 minutes.
• Spot test using the reagent is done on any plank. The change in colour to deep red (Fig
4) indicates the presence of preservatives.