Correct option is D
Fire resistance of timber can be achieved by soaking it in Ammonium Sulphate solution. This
process is called Ammonium Sulphate Treatment (AST) and involves saturating the wood with the solution to create a protective layer against fire. This treatment is particularly useful for timber used in construction or furniture that is susceptible to fire damage. The process of Ammonium Sulphate Treatment involves the following steps:
1. Selection of timber: Only timber with high moisture content should be chosen for this treatment as it can better absorb the ammonium sulphate solution.
2. Preparation of solution: Ammonium Sulphate solution is prepared by dissolving the chemical in
water. The concentration of the solution depends on the type of timber and the required level of fire
resistance.
3. Soaking the timber: The timber is immersed in the solution for a specific period, usually ranging from 6 to 24 hours. The solution penetrates the wood and replaces moisture, making it less flammable.
4. Drying the timber: After soaking, the timber is dried to remove excess moisture. The drying process can take several days to a few weeks depending on the size and type of timber.
5. Finishing: The treated timber can be coated with a fire- retardant paint or varnish for added protection.
