What is a 'graveyard' test?

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.

IS 4833

: 1993

Methods for field testing of preservatives in wood

CurrentSpecializedTesting MethodMaterials Science · Timber and Timber Stores

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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

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)

Practical Notes

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.