Methods of laboratory testing of wood preservatives against fungi and borers (powder post beetles) : Part 2 Determination of threshold values of wood preservatives against borers (powder post beetles)

IS 4873 Part 2: Scope Summary

• Scope: Defines methods to determine threshold values of wood preservatives against borers (Powder Post Beetles).
• Purpose: Establish minimum effective concentrations of preservatives to prevent borer infestation.
• Application: Used for testing and analyzing wood treated with preservatives.

Key Points:

• Test Result Rounding: Final values must be rounded per IS 2:1960 rules.
• Significant Figures: Retain same significant digits as specified values in the standard.

Typical Procedure (Conceptual):

1. Treat wood samples with varying preservative concentrations.
2. Expose samples to borers.
3. Observe infestation levels.
4. Determine threshold concentration where infestation is inhibited.

No direct formulas or tables are provided in the scope clause, but testing follows statistical analysis of infestation data to identify threshold values.

flowchart LR
    A[Treated Wood Samples] --> B[Exposure to Borers]
    B --> C[Observation of Infestation]
    C --> D[Analysis of Results]
    D --> E[Determine Threshold Preservative Value]

For detailed test methods and values, refer to the full IS 4873 Part 2:2008 document.

IS 4873 Part 2 — Method of Test: Key Points

• Rounding Off Results:
  Follow IS 2:1960 for rounding test results. Retain the same number of significant figures as the specified value in the standard.

• Preparation of Test Samples (Clause 3.2.2):

  • Condition samples for 2 weeks at 25° to 30°C and 70-75% RH to reach ~15% moisture content.
  • Seal end grain with paraffin wax or suitable sealant to prevent preservative penetration through ends.
  • Prepare untreated control blocks similarly sealed.

• Sample Quantities:

  • 10 samples treated with preservative at each concentration.
  • 5 samples treated with solvent only.
  • 5 untreated control samples.

Summary Table of Sample Requirements

This ensures standardized conditioning and testing for reliable preservative efficacy evaluation.

IS 4873 Part 2: Preparation of Test Samples (Clause 3.2.2)

• Conditioning:

  • Temperature: 25° to 30°C
  • Relative Humidity: 70 to 75%
  • Duration: 2 weeks
  • Purpose: Achieve equilibrium moisture content ≈ 15%

• Sample End-Grain Sealing:

  • Use paraffin wax or suitable sealant
  • Prevents undue preservative penetration through ends

• Sample Quantity per Test:

  Sample Type	Number of Samples
  Treated with preservative	10 (per concentration)
  Treated with solvent only	5
  Untreated control (end-coated)	5

• Rounding Off Results:
  Follow IS 2:1960 rules, retaining significant digits equal to the specified values.

Summary Flow for Sample Preparation

flowchart TD
    A[Select Wood Blocks] --> B[Condition 2 weeks at 25-30°C, 70-75% RH]
    B --> C[Seal End Grain with Paraffin Wax]
    C --> D{Sample Type}
    D -->|Preservative Treatment| E[10 Samples per Concentration]
    D -->|Solvent Only| F[5 Samples]
    D -->|Untreated Control| G[5 Samples]

This ensures uniform moisture content and prevents preservative entry through ends, critical for consistent test results.

IS 4873 Part 2: Principle of the Test - Key Points

1. Test Sample Preparation (Clause 3.2.2)

• Conditioning: Samples conditioned for 2 weeks at 25° to 30°C and 70-75% RH to reach ~15% moisture content.
• Sealing: End grain sealed with paraffin wax or equivalent to prevent preservative penetration through ends.
• Control Samples: Untreated blocks also sealed similarly.

2. Sample Quantity

3. Rounding Off Results (Method of Test)

• Final test values rounded per IS 2:1960 rules.
• Retain significant figures equal to those specified in the standard.

Summary Diagram of Test Preparation

flowchart TD
    A[Start: Select Samples] --> B[Condition at 25-30°C, 70-75% RH for 2 weeks]
    B --> C[Seal end grain with paraffin wax]
    C --> D{Sample Type?}
    D -->|Preservative| E[Treat with preservative (10 samples)]
    D -->|Solvent| F[Treat with solvent only (5 samples)]
    D -->|Control| G[Untreated control (5 samples)]
    E & F & G --> H[Test & Record Results]
    H --> I[Round off as per IS 2:1960]

This ensures uniform moisture content and controlled preservative penetration for reliable, comparable test results.

IS 4873 Part 2: Test Sample Preparation Summary

1. Conditioning of Samples (Clause 3.2.2)

• Temperature: 25°C to 30°C
• Relative Humidity: 70% to 75%
• Duration: 2 weeks
• Goal: Achieve ~15% equilibrium moisture content
• End Grain Treatment: Seal with paraffin wax or suitable sealant to prevent preservative penetration through ends.

2. Sample Numbers Required

3. Additional Notes

• Untreated controls must be end-coated similarly.
• Results should be rounded per IS 2:1960 rounding rules, maintaining significant figures as per standard.

This ensures uniformity and reliability in preservative treatment testing.

IS 4873 Part 2: Treatment Procedure Summary

Key Steps & Specifications (Clause 3.3)

• Dilutions: Prepare ≥5 preservative concentrations (weight/weight basis), centered around expected toxic limit.
  • Unknown toxic limit: start with widely spaced geometric series, then finer arithmetic series.
• Solvent Use:
  • Water-soluble preservatives → freshly prepared aqueous solutions.
  • Insoluble preservatives → dissolve in volatile solvents (e.g., benzene) that leave no toxic residue.
• Sample Treatment:
  • Immerse 10% concentration test samples for 1 min.
  • Treat from most dilute to most concentrated.
  • Controls: 5 samples treated with solvent/emulsion without toxic ingredients.
• Post-treatment:
  • Shake off excess, blot, and reweigh samples.
  • Calculate preservative uptake:
    [ \text{Uptake} = (\text{Weight after treatment} - \text{Initial weight}) \times \text{Concentration} ]
  • Select 5 blocks per concentration with uptake variation ≤15%.
  • Dry samples at ≤30°C until control samples return to initial weight.
• Conditioning (Clause 3.2.2):
  • Condition blocks 2 weeks at 25–30°C, 70–75% RH for ~15% moisture content.
  • Seal end grain with paraffin wax.
• Sample Numbers:
  • 10 per concentration treated.
  • 5 solvent-only treated controls.
  • 5 untreated controls.

Evaluation (Clause 3.6)

• Record:
  • Number of samples with exit holes.
  • Treated samples without exit holes but with live larvae.
• Toxic limit: Interval between highest concentration with beetle emergence/live larvae and next higher concentration with no emergence/all larvae dead.
• Express concentrations in kg/m³ of wood.

Quick Reference Table: Sample Preparation & Testing

IS 4873 Part 2: Test Insects for Powder Post Beetle Attack

Key Specifications (Clauses 3.1, 3.4, 3.5, 3.6)

• Test Insects: Adults of Lyctus brunneus or Minthia rugicollis from lab cultures.
• Culture Initiation: Use naturally infested wood + untreated feeder wood (semul/mango/rubber/bahera/tapioca chips with starch).
• Test Setup:
  • Samples stored singly in glass containers with cambric covers.
  • Each sample exposed to 4 pairs of beetles or infested material.
  • Conditions: 25–30°C, 70–75% RH.
• Duration: Until all beetles die; emergence of adults monitored (6-8 months).
• Examination: Check for exit holes; split samples to detect live/dead larvae or tunnels.

Evaluation (Clause 3.6)

• Threshold Value (Toxic Limit):
  Interval between:

  • Highest concentration where adults/larvae emerge, and
  • Next higher concentration with no adult emergence and all larvae dead.

• Units: Kilogrammes per cubic metre (kg/m³) of wood.

• Reporting:

  • Concentration of preservative solution used.
  • Diluents used.
  • Time between treatment and insect exposure.

Visual Starch Test (Annex A)

• Starch presence essential for larval development.
• Visual test to confirm starch content before testing.

Summary Table: Test Setup Parameters

flowchart TD
    A[Obtain naturally infested wood] --> B[Maintain lab culture of beetles]
    B --> C[Prepare test samples with

IS 4873 Part 2: Examination of Test Samples — Key Points

Sample Preparation (Clause 3.2 & 3.2.1)

• Wood species: Semul, rubber, or mango.
• Sample size:
  • Length = 100 mm
  • Width = 40 mm
  • Thickness = 12.5 mm
• Orientation: Long axis parallel to grain; wide face tangential to growth rings.
• Condition:
  • Open-piled and air-dried in a well-ventilated room (no kiln or heating).
  • Use heartwood only, free from knots, abnormalities, or irregular growth.
• Rejection criteria: Samples with inadequate starch content (tested per Annex A) must be discarded.

Rounding Off (IS 2:1960)

• Final test values are rounded to the same number of significant digits as the specified value.

Summary Table: Sample Dimensions

flowchart LR
    A[Select timber (semul/rubber/mango)] --> B[Cut samples 100x40x12.5 mm]
    B --> C[Align long axis with grain]
    C --> D[Open-pile dry in ventilated room]
    D --> E{Test starch content}
    E -- Adequate --> F[Use sample for testing]
    E -- Inadequate --> G[Reject sample]

This ensures consistency and reliability in test results per IS 4873 Part 2.

IS 4873 Part 2 - Clause 3.6: Evaluation and Reporting of Results

• Data to Record:

  • Number of treated and untreated samples with exit holes.
  • Number of treated samples without exit holes but containing live larvae.

• Threshold Value (Toxic Limit):

  • Defined as the interval between:
    • The highest concentration where adult beetles emerge or live larvae are found.
    • The next highest concentration where no adults emerge and all larvae are dead.
  • Expressed in kg/m³ of wood.

• Additional Reporting:

  • Concentration of the treating solution used.
  • Type of diluents employed.
  • Time interval between impregnation and exposure to infestation.

Summary Table for Reporting

Notes on Rounding (IS 2:1960)

• Final test values must be rounded off matching the significant figures of the specified value.

flowchart LR
    A[Prepare Samples] --> B[Impregnate with Treatment]
    B --> C[Expose to Infestation]
    C --> D{Check Samples}
    D -->|Exit Holes Present| E[Record Number]
    D -->|No Exit Holes| F{Live Larvae?}
    F -->|Yes| G[Record Number]
    F -->|No| H[Record as Treated & Safe]
    E & G --> I[Determine Toxic Limit]
    I --> J[Report Concentration, Diluents, Interval]

This process ensures consistent and standardized evaluation of wood treatment efficacy against beetle infestation per IS 4873 Part 2.

IS 4873 Part 2: Method of Testing for Starch Content (Annex A & Clauses 3.2, 3.6)

Sample Preparation (Clause 3.2.1)

• Sample size: 100 mm × 40 mm × 12.5 mm
• Orientation: Long axis parallel to grain; wide face tangential to growth rings
• Wood species: Semul, rubber, or mango
• Condition: Open-piled, air-dried (no kiln or heat drying)
• Quality: Clean, bright, knot-free, heartwood with no structural abnormalities

Starch Content Test (Annex A)

• Purpose: Visual test to assess starch adequacy for Lyctus/Minthea larvae development
• Procedure: Test each prepared sample visually for starch presence
• Outcome: Reject samples with inadequate starch content

Evaluation and Reporting (Clause 3.6)

• Record:
  • Number of samples with exit holes (treated & untreated)
  • Number of treated samples without exit holes but with live larvae
• Define threshold (toxic) limit as the concentration interval between:
  • Highest concentration with beetle emergence or live larvae
  • Next higher concentration with no emergence and all larvae dead
• Express concentrations in kg/m³ of wood
• Report:
  • Concentration of treatment solution required
  • Diluents used
  • Time interval between impregnation and infestation exposure

Summary Table: Sample Dimensions & Conditions

flowchart TD
    A[Wood Selection] --> B[Cut Samples (100x40x12.5 mm)]
    B --> C[Orientation: Grain & Growth Rings]
    C --> D[Air Dry Samples (No Heat)]
    D --> E[Visual Starch Test]
    E -->|Adequate Starch| F[Sample Accepted]
    E

IS 4873 Part 2: Committee Composition & Key Specifications

Committee Composition (Annex B)

• The Timber and Timber Stores Sectional Committee, CED 9 is responsible for this standard.
• Members include representatives from:
  • Government bodies (Forest Departments, Directorate Generals)
  • Research Institutes (Forest Research Institute, Indian Plywood Industries, Institute of Wood Science & Technology)
  • Industry (Bamboo Society, Plywood Industry Federation)
  • Other organizations (Ministry of Defence, Rubber Board, Timber Development Association)
• Chairman: Shri Shyam Sunder (Personal capacity, Bangalore)
• Convener (Subcommittee on Timber Terminology, etc.): Dr. R. V. Rao (Institute of Wood Science & Technology)

Key Specifications for Test Samples (Clause 3.2.2)

• Conditioning: 2 weeks at 25–30°C & 70–75% RH to reach ~15% moisture content.
• End grain sealing: Seal with paraffin wax or suitable sealant to prevent preservative penetration.
• Sample numbers per test:
  • 10 treated with preservative per concentration
  • 5 treated with solvent only
  • 5 untreated controls

Summary Table: Sample Preparation

If you need specific formulas or test procedures, please specify the clause or test type.