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IS 6341:1971 is the Indian Standard (BIS) for method of laboratory test for the efficacy of wood preservatives against soft rot. 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
! 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.
EN 807:2013CEN (European Committee for Standardization), Europe
HighCurrent
Wood preservatives - Determination of the effectiveness against soft rotting micro-fungi and other soil inhabiting micro-organisms
Specifies a laboratory method for determining the protective efficacy of wood preservatives against soft rot fungi using unsterile soil.
AWPA E14-19AWPA (American Wood Protection Association), USA
HighCurrent
Standard Method for Evaluating Wood Preservatives in an Unsterile Soil Test
Describes a laboratory test to determine the relative effectiveness of preservatives in wood exposed to unsterile soil, a key environment for soft rot.
BS 7066-2:1989BSI (British Standards Institution), UK
HighWithdrawn
Wood preservatives. Determination of the toxic values against soft rot fungi
A direct predecessor to European standards, it detailed a method for finding toxic limits of preservatives against soft rot.
JIS K 1571:2010JSA (Japanese Standards Association), Japan
MediumCurrent
Test methods for performance of wood preservatives
A comprehensive standard that includes a soil bed test (Test 4) for evaluating preservative performance against decay, including soft rot.
Key Differences
≠IS 6341 specifies the use of a pure culture of Chaetomium globosum, whereas modern standards like EN 807 and AWPA E14 primarily use unsterile soil, relying on its natural microflora to provide a more realistic but less controlled test environment.
≠The primary assessment criterion in IS 6341 is mass loss. EN 807 requires both mass loss and, for hardwoods, measurement of bending strength loss, which is considered a more sensitive indicator of soft rot decay.
≠Test specimen dimensions vary significantly. IS 6341 uses 40x10x5 mm blocks, EN 807 uses 50x25x15 mm blocks, and AWPA E14 uses 19x19x19 mm cubes. This affects the surface area to volume ratio, influencing decay rates.
≠IS 6341 is less prescriptive about the test's validity criteria, stating decay must be 'sufficient'. In contrast, EN 807 requires a minimum average mass loss of 20% in untreated control blocks for the test to be valid.
Key Similarities
≈All standards are based on the fundamental principle of exposing preservative-treated wood specimens to a soft-rot-conducive environment to determine preservative efficacy.
≈The use of mass loss as a quantitative measure of decay is a common feature across all the compared standards, forming a basis for calculating preservative effectiveness.
≈All methodologies mandate the inclusion of untreated and/or solvent-treated control specimens to validate the test conditions and provide a baseline for decay against which treated samples are compared.
≈The incubation conditions are broadly similar, requiring controlled high humidity (over 90%) and elevated temperatures (typically 25-30°C) to accelerate microbial activity.
Parameter Comparison
Parameter
IS Value
International
Source
Primary Test Organism(s)
Pure culture of Chaetomium globosum (ATCC 6205) or soil burial.
Natural microflora in unsterile horticultural soil.
EN 807:2013
Primary Assessment Method
Mass loss percentage.
Mass loss percentage and visual rating (0-10 scale).
AWPA E14-19
Test Block Size
40 x 10 x 5 mm
50 x 25 x 15 mm
EN 807:2013
Incubation Temperature
27 ± 1 °C
27 ± 2 °C
AWPA E14-19
Incubation Period
8 to 16 weeks
12 weeks (can be adjusted based on decay rate in controls)
EN 807:2013
Test Validity (Control Mass Loss)
Not explicitly quantified; decay must be 'sufficient'.
Mean mass loss in untreated controls must be at least 20%.
EN 807:2013
Recommended Softwood Species
Pinus roxburghii (Chir)
Pinus sylvestris (Scots pine)
EN 807:2013
Strength Loss Assessment
Not required.
Required for hardwoods (bending strength); optional for softwoods.
EN 807:2013
⚠ Verify details from original standards before use
Key Values4
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
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.