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IS 4833:1993 is the Indian Standard (BIS) for methods for field testing of preservatives in wood. This standard establishes the procedures for conducting field (graveyard) tests to evaluate the long-term effectiveness of wood preservatives against decay fungi and termites under natural soil-contact conditions.
Methods for field testing of preservatives in wood
! Graveyard tests are long-term empirical evaluations; the selected test site must have a proven, active population of termites and severe fungal decay hazard.
! Always install untreated control specimens of the same timber species to baseline the natural pest activity and confirm the validity of the exposure site.
! Because evaluation is primarily visual and tactile (using a probe), consistency is critical. Ideally, the same trained personnel should conduct the periodic inspections over the years.
EN 252:2014+A1:2018CEN (European Committee for Standardization), Europe
HighCurrent
Field test method for determining the protective effectiveness of a wood preservative in ground contact
Specifies a method for evaluating the performance of wood preservatives in stakes in direct contact with the ground.
AWPA E7-19AWPA (American Wood Protection Association), USA
HighCurrent
Standard Method for Evaluating Wood Preservatives by Field Tests with Stakes
Details procedures for long-term field testing of treated wood stakes to assess preservative efficacy against decay and termites.
ASTM D1758-15(2021)ASTM International, USA
HighCurrent
Standard Test Method for Evaluating Wood Preservatives by Field Tests with Stakes
Provides a standardized method for evaluating wood preservatives via field stake tests, closely harmonized with AWPA E7.
JIS K 1571:2010JSA (Japanese Standards Association), Japan
MediumCurrent
Test methods for performance of wood preservatives
A comprehensive standard that includes a field stake test method among other laboratory and field performance tests.
Key Differences
≠IS 4833 specifies a larger test stake cross-section (50x50 mm) compared to the more common 25x50 mm in EN 252 or 19x19 mm in AWPA E7, which can influence the rate of deterioration.
≠The evaluation rating systems differ significantly. IS 4833 uses a 100-0 scale for decay and a descriptive scale (A-E) for termites, whereas AWPA E7 uses a unified 10-0 logarithmic scale for both, and EN 252 uses a 0-4 scale (0=sound, 4=failed).
≠International standards like EN 252 and AWPA E7 place stronger emphasis on co-testing with specified reference preservatives (e.g., CCA, Creosote) to benchmark the performance of new candidates, a practice less explicitly mandated in IS 4833.
≠IS 4833 specifies locally relevant Indian timber species (e.g., Chir, Mango), while EN 252 mandates Scots pine (Pinus sylvestris) and AWPA/ASTM standards typically use Southern pine (Pinus spp.).
Key Similarities
≈All standards are based on the fundamental principle of exposing treated wood specimens to a natural, biologically active field environment to assess long-term performance.
≈The requirement to include untreated control stakes in the test is a universal feature, serving as a benchmark for the biological hazard level of the test site.
≈All standards prescribe a regimen of periodic (typically annual) inspection, where stakes are removed, cleaned, visually inspected and rated for decay and insect attack.
≈The criteria for selecting a suitable test site are highly similar, requiring known high decay and/or termite hazards, good drainage, and avoidance of contaminated or unusual soil conditions.
10 (but 20 is recommended for standardization purposes)
EN 252:2014
Specified Timber (Europe)
Chir (Pinus roxburghii), Mango (Mangifera indica), etc.
Scots pine (Pinus sylvestris) sapwood
EN 252:2014
Specified Timber (USA)
Chir (Pinus roxburghii), Mango (Mangifera indica), etc.
Southern Pine (Pinus spp.) sapwood
AWPA E7-19
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
standard specimen size50 mm x 50 mm x 600 mm
burial depth300 mm (half the stake length)
minimum replicates10 specimens per treatment variable
inspection frequencyEvery 6 months to 1 year
Key Formulas
R = (G x C) / V — Retention of preservative in wood (where G is weight of treating solution absorbed, C is concentration of preservative, V is volume of specimen)
Tables & Referenced Sections
Key Tables
Table 1 - Visual rating scale for evaluating fungal decay
Table 2 - Visual rating scale for evaluating termite attack
Key Clauses
Clause 4 - Preparation of Test Specimens
Clause 5 - Treatment of Specimens
Clause 6 - Field Test Yard (Graveyard) Requirements
It is an established field testing method where standardized wood stakes are partially buried in the ground in an outdoor test yard to undergo natural exposure to soil, moisture, decay fungi, and termites.
How is the performance of a wood preservative evaluated?+
Performance is evaluated by periodically extracting the stakes, scraping off the soil, and visually rating the extent of biological degradation on a standardized scale (e.g., from completely sound to destroyed).
Why are untreated controls necessary?+
They serve as a baseline to verify that the test yard possesses sufficient biological hazard; if untreated controls do not decay or suffer termite attack rapidly, the test environment is not aggressive enough for a valid evaluation.