Block Board

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Block Board AS PER IS : 1659:2004

Sonnet Block Board is a lumber-core board made from blocks of wood as per IS : 1659-2004 and comes in two grades with usage depending upon the end use of the products.

MR Grade Block Board is used for interior purpose such as furniture, partition, paneling and ceiling etc.

BWP Grade Block Board is meant for exterior use, in areas where there is a likely exposure to hogh humidity.

Both the above grades of Sonnet Block Boards are fabricated as a five ply construction a central core of wooden strip, two cross bands and two face veneers on each side of the core assembly.

The grain direction of glued core veneers is at right angles to the grain direction of the face veneers in adjacent layers other parameters for processing of Sonnet Gold Block Boards, such as hot-pressing, press temperature and pressure etc., are the same as in plywood processing.

Battens of timber conforming to IS : 1659 as Listed under “Annexure B” are used, after proper treatment and Seasoning as frame and fillers. The fillers used in the board are 25-30 mm wide.

Assembled packs (a central core of a wooden frame, two cross brands and two face veneers) are pressed in a hot press with MF resin with antiborer and anti-borer and anti-termite compounds to make the product termite resistant under high temperature and high pressure.

After being pressed in the hot press, the board is sized in an automatic saw machine followed by proper sanding and finishing processes.

Finally, the finished product, in the case of Sonnet MR Block Board, is given and edge-coating with a primer-coat to arrest exposure to atmospheic moisture which ensurers dimensional stability while in the Sonnet BWP Block Board, the finished product is treated with preservative chemicals termed as CCB treatment at a temperature of about 70°C to make it termite resistant and free from borer.


  • Only select species of timber are used for the manufacture of the core of Sonnet Block Board.
  • The planks are passed through prophylactic treatment by dipping them in concentrated preservative solution with a combination of insecticide and fungicide for long lasting protection.
  • The planks are kiln pressed to less than 8-10% moisture content for proper bonding.
  • Have high dimensional stability with high mechanical properties and excellent screw holding capacity.
  • Do not expand, contract or warp-like solid wood.
  • Sonnet MR/BWP Block Board
  • Thickness : 19 mm, 25 mm
  • Size : 8′ ×4′ , 7′ ×4′ , 8′ ×3′ , 7′ ×3′


Sl. No Test Prescribed Minimum Value for Conformity Observed Value
1. Dimensional changes caused by humidity There shall be no de-lamination in the extreme range of humidity Dimensional change shall not be more than +1 mm in local planeness No de-lamination observed. Dimensional change within the specified limit
2. Water Resistance There shall not be any de-lamination after 72 hours boiling. No de-lamination observed.
3. Adhesion of Piles Minimum pass standard Excellent
4. Modulus of Test No appreciable sign of separation edge. Satisfactory
5. Modulus of Rupture 50 N/ 67
6. Modulus of Elasticity 5000 N/ 6025 N/