What type of decay does this test evaluate?

It specifically evaluates resistance to 'soft rot', a type of fungal decay common in very wet conditions, as distinct from brown or white rot.

How is the preservative's effectiveness determined?

By measuring the percentage mass loss of the treated wood specimen after a 12-week incubation period with a soft rot fungus. Lower mass loss indicates higher efficacy.

What is the primary fungus used in this test?

The standard recommends using a culture of a suitable soft rot fungus, with *Chaetomium globosum* being a commonly used species for this purpose (Clause 5).

What are the test specimens called?

They are referred to as 'test blocks' or 'test specimens', typically small blocks of a specified wood species.

IS 6341

: 1971

Method of laboratory test for the efficacy of wood preservatives against soft rot

CurrentSpecializedTesting MethodMaterials Science · Timber and Timber Stores

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This standard specifies a laboratory method for testing the efficacy of wood preservatives against soft rot fungi. It details the preparation of soil, test specimens, fungal cultures, and the procedure for exposing treated wood blocks to determine their resistance to decay by measuring mass loss.

Method of laboratory test for the efficacy of wood preservatives against soft rot

Quick Reference Values

Test specimen size20 x 20 x 5 mm

Incubation temperature22 ± 1 °C

Incubation period12 weeks

Soil moisture content110 to 130 percent of the water-holding capacity

Key Formulas

Mass Loss (%) = ((W1 - W2) / W1) * 100 — Where W1 is initial dry weight and W2 is final dry weight after test

Practical Notes

This is a soil-block test method, which simulates the conditions of wood in contact with damp soil, a primary environment for soft rot.

The test's validity depends heavily on maintaining sterile conditions to prevent contamination from other microorganisms.

Results are comparative, evaluating the performance of treated wood against untreated control specimens to establish a 'toxic limit' for the preservative.