This standard outlines the classification and quality benchmarks for teak logs intended for timber production. It details the allowable defects, measurement techniques, and grading systems specifically designed for Indian teak logs, ensuring uniformity and reliability for stakeholders in timber processing and construction industries.
Overview
This standard outlines the classification and quality benchmarks for teak logs intended for timber production. It details the allowable defects, measurement techniques, and grading systems specifically designed for Indian teak logs, ensuring uniformity and reliability for stakeholders in timber processing and construction industries.
Audience
Contents
Structure
This section defines the scope including measurements and definitions as per IS 707-1976. Curvature deviations are measured over 2.5 meter segments starting from the butt end, with specified limits and corresponding curvature factors. Final test results are rounded following IS 2-1960 guidelines to maintain consistent significant figures, ensuring standardized evaluation of log straightness.
Definitions in this part align with IS 707-1976 for timber materials. The concept of 'units of defect' quantifies timber degradation due to imperfections. Curvature is measured per 2.5 m length with assigned curvature units based on deviation ranges. Standardized measurement procedures ensure consistent assessment of log dimensions and defects.
This section elaborates on the use of defect units to numerically represent quality loss. It covers rounding off test values as per IS 2-1960, and reiterates curvature measurement methods with detailed deviation thresholds and corresponding defect units, facilitating uniform quality assessment.
Describes formulas to calculate allowable defects for logs longer than 2.5 meters. Grade-specific maximum defect units are provided, with explicit prohibition against filling or masking visible defects. Grading considers expected sawn timber yield and visible defect impacts, with clear guidelines on permissible defect quantities to maintain quality.
Details the grading categories with maximum permissible defect units per grade. Branding requirements include supplier identification, log length, mid-girth, and grade symbols (square, triangle, circle). Grading is based on overall wood quality and defect-related loss, referencing FAO Asia-Pacific grading rules as a basis but customized for Indian logs.
Outlines minimum log dimensions and measurement protocols for defects. Provides formulas to calculate permissible defect units proportional to log length. Curvature limits increase with deviation magnitude and are measured in 2.5-meter segments to control log straightness, ensuring adherence to quality standards.
Specifies that logs must be permanently branded on both ends with supplier ID, length, mid-girth, and grade symbol. Optional ISI certification marks are discussed along with regulatory compliance. Additional requirements include end-coating of logs post-inspection per IS:1141-1973 and rounding off test results in accordance with IS 2-1960.
Frequently Asked
Grade 1 teak logs are permitted a maximum of 2.5 defect units per log as stated in Clause 2.5. These defects correspond to visible imperfections that influence the estimated sawn timber yield under normal processing. Although this represents the upper defect limit, logs with defects at this maximum do not automatically qualify for Grade 1. The grading system is tailored for Indian teak logs, which generally have volumes smaller than 0.6 cubic meters.
While IS 4895 does not prescribe a specific formula for volume calculation, standard methods like the cylindrical volume formula and Smalian's formula are typically used. The cylindrical method calculates volume as π times the radius squared multiplied by length, whereas Smalian's formula averages the cross-sectional areas at both ends multiplied by half the length. These approaches accommodate the taper of logs and are commonly applied for Indian teak logs, which usually have volumes below 0.6 cubic meters.
Defect evaluation involves measuring the shortest distance between log ends to determine length, followed by visual inspection to identify and quantify visible defects affecting timber quality. Estimations consider probable volume loss under standard conversion techniques. The assessment aligns with IS 3364 (Part 1) for defect limits, and grading is based on the estimated sawn timber output and defect severity, ensuring consistent quality control.
Holes with diameters up to 2 millimeters are allowed without restriction. Those between 2 mm and 12 mm can occur up to 5 holes per square meter, with a maximum allowable loss of 25% during conversion. However, holes exceeding 12 mm in diameter are generally prohibited unless a specific agreement is made between buyer and seller.
IS 4895 is tailored for Indian teak logs, which typically have volumes around 0.3 cubic meters, whereas the Asia-Pacific rules apply to larger logs (minimum 0.6 cubic meters) mainly for export purposes. IS 4895 modifies permissible defect limits to reflect the characteristics of Indian logs and uses IS 3364 (Part 1)-1976 for defect evaluation, whereas Asia-Pacific rules follow FAO guidelines. This makes IS 4895 more applicable for domestic grading and timber processing in India.
Ask AI about any clause, requirement, or provision in IS 4895. Get instant, clause-cited responses powered by our indexed library.
Free tier includes 150 queries (50 AI + 100 Reference) · No credit card required