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In which type of seasoning is timber immersed in a solution of suitable salt, and then taken out and seasoned in ordinary way?
Kiln seasoning
Chemical seasoning
Boiling
Water seasoning
Chemical seasoning
Chemical seasoning, also known as salt seasoning, involves immersing timber in a concentrated solution of chemical salts like sodium chloride or urea. The chemical salt draws out moisture from the interior of the timber to the surface via osmosis, ensuring uniform drying and reducing the risk of surface cracking or splitting.
IS 1141:1993 (Code of practice for seasoning of timber)
Chemical seasoning, also known as salt seasoning, involves immersing timber in a concentrated solution of chemical salts like sodium chloride or urea. The chemical salt draws out moisture from the interior of the timber to the surface via osmosis, ensuring uniform drying and reducing the risk of surface cracking or splitting.
╬а=iCRT тАФ where ╬а is the osmotic pressure, i is the van 't Hoff factor, C is the molar concentration, R is the gas constant, and T is temperature.
The principle relies on the hygroscopic nature of the salt. By creating a high osmotic pressure at the surface, the salt solution forces the moisture from the core of the timber toward the outer layers. Once the moisture content is reduced to a specific level, the timber is removed and allowed to complete the seasoning process under ordinary atmospheric conditions.
Used to prevent checking, splitting, and honeycombing in refractory timbers.
The chemical salt stays on the surface, helping to maintain surface moisture until the core dries.
It is generally faster than air seasoning for thick timber sections.
Suitable for high-density wood species that are difficult to season by conventional methods.
Reduces internal stress and drying defects.
Faster drying rate for thick timber sections.
Prevents surface cracks effectively.
Increased cost due to chemical procurement.
Possible discoloration of the timber surface.
Potential for increased corrosion if the timber is later used with metal fasteners.
Hardwood timbers prone to surface splitting.
Large dimension timber components requiring high structural integrity.
Chemical seasoning is effectively a pre-treatment to accelerate and control the drying process.
Kiln seasoning uses controlled artificial heat and humidity in an oven, whereas water seasoning involves soaking timber in flowing water to leach out sap before air drying.
B is correct тАФ Chemical seasoning utilizes salt solutions to draw moisture from the timber core to the surface to prevent drying defects.
Always remember that 'Chemical Seasoning' is specifically for preventing defects in difficult-to-season wood, while 'Kiln Seasoning' is the most efficient industrial method for mass production.
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