Performance requirements for adhesive for structural laminated wood products for use under exterior exposure conditions

IS 9188: Scope & Key Specifications Summary

IS 9188 covers the specifications for adhesives used in structural woodwork. It aligns with IS 707-1976 definitions and emphasizes practical field application.

Key Points from Clause 8.2 (Applications):

• Moisture Content of Wood at Gluing: Typically 8-12% moisture content is ideal for good adhesion.
• Surface Preparation: Surfaces must be clean, dry, and free from dust, grease, or other contaminants.
• Application Methods: Single or double adhesive spread depending on joint type.
• Minimum Adhesive Spread: Varies with wood type and joint, generally 150-250 g/m² per side.
• Assembly Times:
  • Open assembly time: Time after adhesive application before joining (usually 5-15 minutes).
  • Closed assembly time: Time under pressure for initial bond (typically 15-30 minutes).
• Pressure Range: Recommended pressure is 0.1 - 0.7 N/mm² (1 - 7 kg/cm²) depending on adhesive and wood.
• Cure Time & Temperature: Minimum cure time is 24 hours at room temperature (~20-25°C), or shorter at elevated temperatures (~50-60°C).

Rounding Off Results (Clause 0.4):

• Follow IS 2-1960 for rounding off test values.
• Retain the same number of significant digits as the specified values.

Summary Table: Adhesive Application Parameters

flowchart LR
    A[Wood Preparation] --> B[Adhesive Application]
    B --> C{Assembly Time}
    C -->|Open Assembly| D[Join Wood]
    D --> E{Pressure Application}
    E --> F[Curing

IS 9188 - Definitions Summary

• Reference Standard: Definitions primarily refer to IS 707-1976 (Specification for Mild Steel and Medium Tensile Steel Bars and Hard-Drawn Steel Wire for Concrete Reinforcement).

• Rounding Off:

  • Follow IS 2-1960 for rounding final test or analysis values.
  • Retain the same number of significant digits as the specified value.

• Key Points:

  • Definitions align with international standards and Indian practices.
  • No explicit formulas or tables are provided under the definitions clause itself.

Additional Notes (from IS 707 & IS 2):

flowchart TD
    A[IS 9188 Definitions] --> B[Refer IS 707-1976]
    A --> C[Rounding per IS 2-1960]
    B --> D[Steel Types & Properties]
    C --> E[Significant Figures]

For detailed steel properties and mechanical characteristics, consult IS 707-1976 directly.

IS 9188 - Adhesive Composition & Classification

Adhesive Composition (Clause 3.1)

• Adhesive is primarily reaction products of phenol and/or resorcinol with an aldehyde.
• Common aldehyde: Formaldehyde.
• This makes adhesives phenolic, resorcinolic, or phenol-resorcinol based.

Classification (Clause 4.1)

• Adhesives are classified by manufacturer as:
  • Phenol-based
  • Resorcinol-based
  • Phenol-Resorcinol-based

Preparation (Clause 1.1)

• Prepare 100 g adhesive per manufacturer's instructions.
• Use distilled water only if water is required for mixing.

Manufacturer's Responsibilities (Clause 8.1)

• Provide written instructions including:
  • Chemical type of adhesive.
  • Storage conditions.
  • Mixing procedures.
  • Relevant usage data for laminated wood products.

Summary Table: Adhesive Types

flowchart LR
    A[Phenol/Resorcinol] --> B[Reaction with Aldehyde]
    B --> C[Adhesive]
    C --> D{Classification}
    D --> E[Phenol-based]
    D --> F[Resorcinol-based]
    D --> G[Phenol-Resorcinol-based]

Note: Follow manufacturer's instructions strictly for adhesive preparation and application to ensure product performance.

IS 9188 - Adhesive Classification Key Points

1. Classification Basis (Clause 4.1):
   Adhesives are classified by the manufacturer based on the general type:

   • Phenol-based
   • Resorcinol-based
   • Phenol-resorcinol based

2. Adhesive Composition (Clause 3.1):
   Adhesives must primarily consist of reaction products of phenol and/or resorcinol with an aldehyde.

3. Rounding Off Results (Clause 0.4):
   Test results should be rounded off as per IS 2:1960, maintaining the same number of significant digits as the specified values.

Summary Table: Adhesive Types

Additional Notes

• Adhesive classification guides selection for durability, resistance, and application.
• Testing includes shear resistance under compression (see Appendix C).

flowchart TD
    A[Adhesive Classification] --> B[Phenol-based]
    A --> C[Resorcinol-based]
    A --> D[Phenol-Resorcinol-based]
    B --> E[Exterior, water-resistant]
    C --> F[High durability, structural]
    D --> G[Enhanced performance]

For detailed test procedures and values, refer to IS 9188 clauses on testing and Appendix C.

IS 9188: Performance Requirements for Adhesives in Structural Laminated Wood (Exterior Use)

Key Performance Requirements (Summary)

• Adhesive Durability: Must resist delamination under exterior exposure conditions.
• Resistance to Delamination: Verified through cyclic testing (Clause 5.3.1, Appendix D).
• Test Specimen: Prepared as per Appendix D to simulate real-life stress cycles.

Important Specifications from Appendix D (Clause 5.3.1)

Typical Test Procedure Outline

flowchart TD
    A[Prepare Test Specimen] --> B[Subject to Cyclic Wet-Dry Exposure]
    B --> C[Measure Delamination Area]
    C --> D{Delamination ≤ 5%?}
    D -- Yes --> E[Adhesive Passes Test]
    D -- No --> F[Adhesive Fails Test]

Additional Notes

• Adhesives must comply with exterior durability, moisture resistance, and mechanical strength.
• Refer to IS 7189 for adhesive bond strength testing methods.
• Performance criteria ensure long-term structural integrity of laminated wood under outdoor conditions.

For detailed formulas and exact test parameters, consult full IS 9188 Appendix D and IS 7189.

IS 9188: Sampling and Test Methods Summary

Sampling (Clause 6.2 & Table 1)

• Sampling is done per lot.
• Number of containers to sample depends on lot size:

• Containers are selected randomly using random number tables (see IS:4905-1968).

Composite Sample Preparation (Clause 6.3)

• From each selected container:
  • Take ~0.25 kg sample from different parts.
  • Mix thoroughly to represent that container.
• Mix equal quantities from all selected containers to form a composite sample ≥ 0.5 kg representing the lot.

Conformity Criterion (Clause 6.4)

• Test the composite sample for all standard requirements.
• Lot is conforming only if composite sample meets all criteria.

Rounding Off (Clause 0.4)

• Test results rounded per IS:2-1960.
• Retain significant figures equal to those in the standard's specified values.

flowchart LR
    A[Select Lot] --> B[Randomly select containers (Table 1)]
    B --> C[Draw ~0.25 kg sample from each container]
    C --> D[Mix samples per container]
    D --> E[Mix equal parts from containers → Composite Sample (≥0.5 kg)]
    E --> F[Test composite sample]
    F --> G{Meets all requirements?}
    G -- Yes --> H[Lot conforms]
    G -- No --> I[Lot does not conform]

This ensures statistically valid sampling and testing for lot conformity per IS 9188.

IS 9188: Marking and Labeling Requirements (Clause 7.1 & 7.1.1)

Each adhesive container must be marked legibly and indelibly with:

• Manufacturer's name or mark
• Description of material
• Batch number
• Date of manufacture
• Expiry date (date beyond which adhesive should not be used under recommended storage)
• Reference to manufacturer's instructions for use
• The phrase: "To be stored in a cool dry place"

Optional:

• ISI Certification Mark (subject to Indian Standards Institution regulations)

Instructions for Use (Clause 8.2) - Key Guidance Points:

• Moisture content range of wood at gluing
• Surface preparation methods
• Application methods (single/double spread)
• Minimum adhesive spread for typical stock
• Open and closed assembly times (min/max)
• Recommended pressure: typically in N/mm² (kg/cm²)
• Minimum cure time and temperature for full bonding

Typical Pressure Range for Wood Adhesives

flowchart LR
    A[Container] --> B{Markings}
    B -->|Manufacturer's name| C[Name/Mark]
    B -->|Material description| D[Material]
    B -->|Batch number| E[Batch No.]
    B -->|Manufacture date| F[Date]
    B -->|Expiry date| G[Expiry]
    B -->|Instructions ref.| H[Instructions]
    B -->|Storage note| I["Cool dry place"]
    B -->|ISI Mark (optional)| J[ISI Certification]

This ensures traceability, quality control, and proper usage per IS 9188.

IS 9188 - Application Guidelines Summary

Clause 8.2 provides essential application parameters for adhesive use in laminated wood:

• Moisture Content: Wood should be within 8-12% moisture content at gluing to ensure good adhesion.

• Surface Preparation: Surfaces must be clean, dry, and free from dust, grease, or loose fibers.

• Application Method:

  • Single spread: Adhesive applied on one surface.
  • Double spread: Adhesive applied on both mating surfaces for better bond.

• Minimum Adhesive Spread:

  • Typically 150-200 g/m² depending on wood species and adhesive type.

• Assembly Times:

  • Open assembly time: Usually 5-10 minutes (time adhesive remains tacky after application).
  • Closed assembly time: Time between pressing and initial set, typically 10-30 minutes.

• Pressure Range:

  • Recommended pressure is 0.7 to 1.5 N/mm² (7 to 15 kg/cm²) to ensure proper bonding.

• Cure Time and Temperature:

  • Minimum cure time: 4-6 hours at 20-25°C or shorter at elevated temperatures (e.g., 60°C for 1 hour).

Quick Reference Table

Notes:

• Adhesive manufacturer instructions (Clause 8.1) must be strictly followed.
• Testing for shear resistance (Appendix C) ensures bond quality.
• Round off test results per IS 2-1960 for compliance.

flowchart TD
    A[Wood Preparation] --> B[Moisture Content 8-12%]
    B -->

IS 9188: pH Determination of Adhesive Films

Key Specifications & Procedure

• Sample Preparation (Clause A-2.1):

  • Stir adhesive thoroughly.
  • Spread ~20 ml in a 0.5 mm thick, 15 x 15 cm film on clean glass.
  • Cure as per manufacturer’s instructions.
  • Peel cured film, grind to pass through 40-micron IS sieve.
  • Weigh 2.0 g ground sample, add 10 ml freshly boiled, cooled distilled water.
  • Stir thoroughly, keep vial stoppered except during pH measurement.
  • Stand for 72 hours at room temperature before testing.

• pH Measurement (Clause A-3.1):

  • Measure pH at 24-hour intervals.
  • Repeat until difference between consecutive readings ≤ 0.05 pH units.
  • Final reading = equilibrium film pH.

• Acceptance Criteria (Clause 5.1):

  • pH of cured adhesive film ≥ 4.0.

Summary Table

flowchart TD
    A[Mix Adhesive] --> B[Spread 0.5 mm film on glass]
    B --> C[Cure as per manufacturer]
    C --> D[Peel film & grind to <40μm]
    D --> E[Weigh 2g + Add 10 ml distilled water]
    E --> F[Stir & stand 72 hrs at room temp]
    F --> G[Measure pH every 24 hrs]
    G --> H{pH difference ≤ 0.05?}
    H -- No --> G
    H -- Yes --> I[Report final pH ≥ 4]
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IS 9188: Preparation of Laminated Wood Test Members

Key Specifications (from Clauses 2.1, 2.2, 5.2.2, Appendix B)

• Width of laminated wood members: Uniformly dressed to 50 mm after conditioning.
• Length of test sections: Cut into 80 mm lengths for shear and delamination tests.
• Conditioning: Members must be conditioned before dressing and cutting.
• Test Types: Resistance to shear by compression loading and resistance to delamination during cyclic tests.

Preparation Steps Summary

1. Select and condition laminated wood as per Appendix B.
2. Dress sides to a uniform width of 50 mm.
3. Cut into 80 mm long test members.
4. Conduct tests as per Fig. 2 (refer IS 9188 for detailed schematic).

Typical Dimensions Table

Conceptual Illustration (Fig. 2 schematic)

flowchart LR
    A[Conditioned Laminated Wood Beam] --> B[Dress sides to 50 mm width]
    B --> C[Cut into 80 mm sections]
    C --> D[Perform shear & delamination tests]

This ensures uniformity and reproducibility in testing adhesive performance and shear resistance.

IS 9188: Resistance to Shear by Compression Loading (Clause 5.2 & Appendix C)

Key Specifications:

• Shear Strength Requirements:
  • Dry condition: ≥ 20 N/mm² (200 kg/cm²)
  • After boiling: ≥ 12 N/mm² (120 kg/cm²)

Testing Setup (Appendix C):

• Test Specimen: Prepared as per Clauses 5.2.1 & 5.2.2.
• Testing Machine:
  • Equipped with a self-aligning shearing tool (Fig. 4) for uniform load application.
  • Load applied continuously at max 1.25 cm/min.
  • Test environment controls moisture to avoid altering specimen moisture content.

Important Notes:

• Uniform shear load application is critical.
• Average shear strength is calculated per group of specimens under consistent manufacturing conditions.

Shear Strength Formula (Conceptual):

[ \tau = \frac{P}{A} ]

Where:

• (\tau) = Shear strength (N/mm²)
• (P) = Shear load at failure (N)
• (A) = Shearing area (mm²)

flowchart LR
    A[Test Specimen] --> B[Placed in Testing Machine]
    B --> C[Shearing Tool with Self-aligning Seat]
    C --> D[Load Applied at ≤1.25 cm/min]
    D --> E[Measure Load at Failure]
    E --> F[Calculate Shear Strength \tau = P/A]
    F --> G{Shear Strength ≥ Limits?}
    G -- Yes --> H[Pass]
    G -- No --> I[Fail]

This ensures reliable determination of resistance to shear by compression loading as per IS 9188.

IS 9188: Delamination Testing Procedures (Clause 5.3.1 & Appendix D)

Key Specifications:

• Delamination Limit: Average delamination ≤ 5% of specimen length after cyclic test.
• Test Specimen: Prepared as per Clause 2.1 and dried as per D-1.2.
• Measurement:
  • Measure total delamination length at specimen ends immediately after final drying.
  • Use a feeler gauge 0.125 mm thick & 2.5 mm wide.
  • Ignore isolated delamination < 2.5 mm long and > 5 mm away from nearest delamination.
  • Sum delamination lengths on both ends.

Testing Procedure Summary (Appendix D):

1. Subject specimen to cyclic test.
2. After drying, measure delamination length at ends.
3. Calculate % delamination = (Total delamination length / Specimen length) × 100.
4. Confirm average delamination ≤ 5%.

Formula:

[ \text{Delamination %} = \frac{\text{Total delamination length (both ends)}}{\text{Specimen length}} \times 100 \leq 5% ]

Visual Summary:

flowchart TD
    A[Test Specimen Preparation] --> B[Cyclic Test]
    B --> C[Final Drying Period]
    C --> D[Measure Delamination Length]
    D --> E[Calculate % Delamination]
    E --> F{Is % ≤ 5%?}
    F -- Yes --> G[Pass]
    F -- No --> H[Fail]

This ensures structural integrity by limiting delamination in wood laminates under cyclic loading.