Logs for production of sliced veneers
2004 Edition

Logs intended for sliced veneer production are required to be free from major defects such as knots, wandering heart, spongy wood, tension or compression wood, twisted or spiral grain, crotch, resin or gum pockets, decay, and active insect infestation. Hollow heart is acceptable provided its diameter does not exceed 10% of the log’s diameter at either end; the volume affected by this defect is subtracted from the total timber volume. Minor defects such as dote, bird peck, wounds, or fire damage are allowed if they are confined to a single quadrant of the log, have a maximum diameter of 12 mm and depth of 40 mm, and do not exceed two occurrences within every 2.5-meter section of the log. Logs must not be artificially dressed or straightened to conceal defects, ensuring the veneer quality remains uncompromised while permitting limited natural imperfections under controlled allowances.

As per the standard, log length is measured in metres and rounded down to the nearest multiple of 0.05 m, representing the total longitudinal extent of the log. Girth measurements are taken in millimetres at the midpoint along the log’s length, rounded down to the nearest 10 mm. For volume calculations, the log is assumed to have a circular cross-section, and volume is computed by the formula: V = (G² / 4π) × L, where G and L are in metres. Measurement and inspection should be conducted in the presence of both purchaser and supplier representatives or according to contractual agreements. Logs are then marked at both ends with the supplier’s identification, length, mid-girth, and designated grade symbols to facilitate traceability and quality assurance.

Logs are categorized into three grades based on their girth dimensions: Grade I includes logs with a girth exceeding 2000 mm; Grade II comprises logs with girth between 1500 mm and 2000 mm; Grade III covers those with girth ranging from 1000 mm to 1500 mm. Each grade is represented by a distinct marking symbol: a square for Grade I, a triangle for Grade II, and a circle for Grade III. The volume of each log is calculated using the formula V = (G² / 4π) × L, where G and L are in metres. Logs are marked on both ends with the supplier’s ID, length, mid-girth, and the respective grade symbol. This classification system aids in the standardized control of veneer log quality.

Yes, the standard mandates that logs receive prophylactic treatment immediately following felling and cross-cutting to prevent end cracking, splitting, fungal infections, and insect attacks. This treatment should comply with the guidelines set out in IS 9104, which details storage and protection methods for logs and sawn timber. Additionally, logs must be free from defects such as knots, wandering heart, spongy or tension wood, twisted grain, crotch, resin pockets, decay, and live insect infestation. Hollow heart defects are tolerable if within 10% of the log diameter and the affected volume is deducted. These preventive measures ensure the logs maintain their structural integrity and suitability for veneer production.

The standard tackles insect damage and decay primarily through required prophylactic treatment and strict defect limitations. According to Clause 8, logs must be treated promptly after felling and cross-cutting following IS 9104 protocols, which protect against end cracking, fungal infections, and insect attacks during storage and handling. Clause 2.5 permits minor defects such as dote, bird peck, wounds, or fire damage only if confined to one quadrant, with maximum dimensions of 12 mm in diameter and 40 mm in depth, and limited to two defects per 2.5-meter log length. These provisions ensure that only structurally sound logs with controlled imperfections are used for veneer slicing, maintaining high quality and durability.