Specification Polyvinyl Acetate Dispersion-Based Adhesives for Wood

IS 4835: Scope & Key Specifications

• Scope:
  IS 4835 covers adhesives for bonding wood and wood-based materials, specifying requirements, testing, and usage guidelines.

• Rounding Off (Clause 0.7):
  Results from tests or calculations must be rounded as per IS 2:1960, retaining the same significant figures as the standard’s specified values.

• Reference Standards (Clause 2.1):
  Definitions refer to:

  • IS 707-1976 (Wood and plywood terminology)
  • IS 848-1974 (Veneers)
  • IS 851-1978 (Plywood)

• Manufacturer Instructions (Clause A-1.1):
  Must include:

  • Storage in sealed containers
  • Preparation & mixing methods
  • Thinning control
  • Application procedure: moisture content, surface prep, spread rates, glue line thickness, assembly times, pressure (kg/cm²), post-treatment, cleaning, compatible materials, temperature/time for pressure, setting time, viscosity correction, safety.

Typical Key Parameters for Adhesive Application

flowchart TD
    A[Adhesive Storage] --> B[Preparation & Mixing]
    B --> C[Surface Cleaning & Prep]
    C --> D[Application: Spread & Pressure]
    D --> E[Assembly Time & Setting]
    E --> F[Post-Treatment & Cleaning]
    F --> G[Safety Precautions]

Note: Always follow manufacturer’s detailed instructions per Clause A-1.1 for best results.

IS 4835: References Summary

• Rounding off values:
  Follow IS 2-1960 for rounding test or analysis results.

  • Retain the same number of significant figures as specified in IS 4835.

• Definitions:
  Use definitions from:

  • IS 707-1976
  • IS 848-1974
  • IS 851-1978

• Adhesive information:
  Refer to Appendix A for detailed adhesive usage instructions.

• International coordination:
  The standard aligns with global practices while considering Indian field conditions.

Key Reference Table

For precise adhesive specifications and test methods, consult Appendix A of IS 4835.

flowchart LR
    A[IS 4835] --> B[IS 2-1960 (Rounding off)]
    A --> C[IS 707-1976 (Definitions)]
    A --> D[IS 848-1974 (Plywood Specs)]
    A --> E[IS 851-1978 (Timber Grading)]
    A --> F[Appendix A (Adhesive Info)]

IS 4835: Definition Summary

• Clause 2.1: Definitions in IS 4835 refer to those in:

  • IS 707-1961: Adhesives for plywood
  • IS 848-1974: Specification for synthetic resin adhesives for plywood
  • IS 851-1978: Test methods for adhesives

• Key points:

  • The standard aligns with international practices (Clause 0.6).
  • Test results must be rounded as per IS 2-1960 rules (Clause 0.7).
  • Relevant adhesive data must be provided as per Appendix A.

Important Reference: Rounding off (IS 2-1960)

Summary Table: Key Definitions Source

If you need detailed formulas or tables for adhesive strength, viscosity, or bonding characteristics, please specify!

IS 4835 – Keeping Qualities of Polyvinyl Acetate Adhesives

Key Points on Keeping Qualities (Clause 6.7)

• Stability Requirements: Adhesive must maintain:
  • Solid content
  • pH
  • Mass per litre
  • Adhesive strength
    throughout the storage period at the manufacturer’s recommended conditions and at the specified maximum temperature.
• Manufacturer’s Certification: Must certify that the adhesive meets stability requirements after testing.

Important Notes:

• Rounding Off (Clause 0.7): Test results should be rounded as per IS 2:1960 to the same decimal places as specified values.
• Formulation Basis (Clause 3.1): Adhesives are based on polyvinyl acetate dispersions.

Typical Parameters to Monitor for Keeping Qualities:

Stability Testing Conceptual Flow:

flowchart LR
    A[Start: Adhesive Sample] --> B[Store at Specified Temperature]
    B --> C{Storage Period Completed?}
    C -- No --> B
    C -- Yes --> D[Test Solid Content, pH, Mass/Litre, Strength]
    D --> E{Meets Requirements?}
    E -- Yes --> F[Certificate of Stability]
    E -- No --> G[Reject or Reformulate]

Summary: IS 4835 requires polyvinyl acetate adhesives to maintain key physical and chemical properties during storage, certified by the manufacturer, ensuring consistent performance in the field.

IS 4835 Sampling Key Points & Table

Sampling Definition (Clause 1.1, B-1.1)

• A lot = material from the same batch or blending operation under identical processing.

Sampling Procedure (Clause 5.1.1 & 5.1)

• Before sampling, thoroughly stir bulk polyvinyl acetate dispersion to ensure homogeneity due to settling.
• Sampling follows Appendix B instructions.

Sampling Table for Small Containers (Clause 2.2, Table B-2.2)

Summary:

• Stir bulk material well before sampling.
• For small containers, start with 2 samples for up to 25 containers, then add 1 sample per additional 25 containers.
• Sampling ensures representative testing of adhesive quality.

flowchart TD
    A[Bulk Material] --> B[Stir Thoroughly]
    B --> C[Sampling as per Appendix B]
    C --> D[Number of Containers ≤ 25?]
    D -- Yes --> E[Take 2 Samples]
    D -- No --> F[Calculate Samples: 2 + (No. of Containers - 25)/25]
    F --> G[Take Calculated Number of Samples]

This ensures reliable quality control per IS 4835.

IS 4835: Test Requirements Summary

Key Clauses:

• Clause 6.0: Tests must be conducted on each sample; samples must meet requirements in Clauses 6.1 to 6.10.
• Clause 0.7: Test results must be rounded as per IS 2-1960 (rounding rules consistent with specified values).
• Clause 5.1.2: Each sample must comply with Clause 6 requirements.
• Clause 7.2 (Creep Test):
  • Load applied to bottom frame; top frame suspended.
  • Time to joint failure under constant load recorded automatically.

Important Notes:

• Test parameters include mechanical strength, creep resistance, dimensional accuracy, etc.
• Results reporting must be clear, precise, and follow IS 2 rounding rules.

Typical Test Rounding Example (IS 2-1960):

flowchart LR
    A[Sample Preparation] --> B[Test Setup]
    B --> C[Apply Load]
    C --> D[Record Time to Failure]
    D --> E[Analyze & Round Results (IS 2)]
    E --> F[Report Compliance]

This ensures uniformity and reliability in test evaluation per IS 4835.

IS 4835: Marking and Packaging Key Points

Marking Requirements (Clause 7.1 & 7.1.1)

Each container must be legibly and indelibly marked with:

• Manufacturer's name or trade-mark
• Description of material
• Manufacturer's reference number
• Batch number
• Date of manufacture and last recommended use date
• Reference to manufacturer's instructions for use
• The phrase:
  "To be Stored in a Cool Dry Place Until (specified date)"

Additionally, containers may carry the ISI Certification Mark as per the Indian Standards Institution rules, ensuring compliance and quality control.

Packaging Specifications

• Packaging should protect contents from damage and deterioration.
• Must allow for clear visibility of markings.
• Should facilitate safe handling, transport, and storage.

Manufacturer's Information (Appendix A)

• Detailed usage instructions
• Storage conditions
• Safety precautions

Summary Table for Marking on Container

flowchart LR
    A[Container] --> B[Markings]
    B --> C[Manufacturer's Name/Trade-mark]
    B --> D[Material Description]
    B --> E[Reference Number]
    B --> F[Batch Number]
    B --> G[Manufacture Date & Expiry Date]
    B --> H[Usage Instructions Reference]
    B --> I[Storage Instructions]
    B --> J[ISI Certification Mark (optional)]

This ensures traceability, quality assurance, and safe use/storage of adhesives as per IS 4835.

IS 4835: Manufacturer's Instructions for Use of Adhesives

Per Clause 1.1 and Appendix A, manufacturers must provide detailed, dated, written instructions covering:

• Storage: Keep adhesive in original sealed containers; store in a cool, dry place (Clause 4.1g).
• Preparation: Mixing/dilution methods, apparatus, handling precautions.
• Thinning Control: Recommended controls during viscosity adjustment.
• Application Procedure:
  • Moisture content range of wood.
  • Surface preparation methods.
  • Application methods (single/double spread).
  • Normal spread amount per glue line.
  • Open and closed assembly times (max/min).
  • Pressure range: kg/cm² (recommended values to be specified).
  • Post-treatment of finished product.
  • Equipment cleaning methods.
  • Compatible materials and temperature/time limits under pressure.
  • Setting time and conditions.
  • Viscosity correction and scum removal.
• Safety: Precautions for workers.

Marking Requirements (Clause 7.1.1):

• Date of manufacture and expiry.
• Reference to instructions.
• ISI Certification Mark as per ISI rules.

Summary Table of Key Parameters to be Provided by Manufacturer

flowchart TD
    A[Adhesive Storage] --> B[Preparation & Mixing]
    B --> C[Application Procedure]
    C --> D[Pressure & Assembly Times]
    D --> E[Post-treatment & Cleaning]
    E --> F[Safety Precautions]
    F --> G[Marking & Certification]

This ensures safe, effective adhesive use complying with IS 4835.

IS 4835: Sampling for Inspection - Key Points

1. Definition of Inspection Lot

• Lot: Material from the same batch or blending operation under identical processing conditions. (Clause B-1.1)

2. Sampling Scheme for Small Size Containers (Clause B-2.2, Table B-2)

Example:

• 25 containers → 2 samples
• 50 containers → 3 samples (2 + 1)
• 75 containers → 4 samples (2 + 2)

3. Sampling Method Reference

• Sampling procedures and tests for adhesives are detailed in Appendix B and Clauses 5.1.1, 6.1 to 6.4.

Summary Table for Sampling

flowchart TD
    A[Start: Number of Containers (N)] --> B{N ≤ 25?}
    B -- Yes --> C[Take 2 Samples]
    B -- No --> D[Calculate extra samples]
    D --> E[Extra Samples = floor((N-25)/25)]
    E --> F[Total Samples = 2 + Extra Samples]
    F --> G[Sampling Complete]
    C --> G

This ensures statistically representative sampling for quality inspection per IS 4835.

IS 4835: Resistance to Sustained Load Test Method (Clause 6.10, Appendix C)

Key Specifications:

• Load applied: 25 kgf (constant sustained load)
• Specimens: Group of 10 test slips
• Minimum average failure time: ≥ 7 days under sustained load

Test Setup:

• Use a special jig (Fig. 2) with:
  • Top frame suspended from support
  • Load applied to bottom frame
  • Specimens laterally supported by small packing pieces
• Conditioning atmosphere maintained for specimens
• Automatic recording devices measure time to failure (creep failure)

Procedure Summary:

1. Prepare and condition test specimens.
2. Mount specimens in jig with proper alignment.
3. Apply 25 kgf sustained load.
4. Record time until joint failure (creep rupture).
5. Calculate mean failure time for 10 specimens.

Reporting:

• Report mean failure time.
• Confirm if mean ≥ 7 days for compliance.

Formula for Mean Failure Time:

[ \text{Mean Failure Time} = \frac{\sum_{i=1}^{10} t_i}{10} ]

where ( t_i ) = failure time of each specimen under 25 kgf load.

flowchart TD
    A[Prepare 10 test specimens] --> B[Condition specimens in atmosphere]
    B --> C[Mount specimens in jig (Fig. 2)]
    C --> D[Apply 25 kgf sustained load]
    D --> E[Record time to failure for each specimen]
    E --> F[Calculate mean failure time]
    F --> G{Mean failure time ≥ 7 days?}
    G -- Yes --> H[Specimens pass sustained load test]
    G -- No --> I[Specimens fail sustained load test]

This method ensures PVAC adhesive joints have adequate creep resistance under sustained load.

IS 4835: Conditioning of Test Specimens - Key Points

Conditioning Atmosphere (Clause 6.1)

• Temperature: 25 ± 1°C
• Relative Humidity: 65 ± 2%
• Duration: Minimum 4 days
• Specimens must be released from clamps before conditioning and remain in this atmosphere until testing.

Preparation Before Conditioning (Clause 5.1)

• Prepare specimens under ordinary room conditions unless otherwise specified.
• Apply adhesive uniformly on one face; join immediately without rubbing.
• Clamp specimens with sufficient pressure and keep clamped at room conditions for at least 8 hours.

Moisture Content Determination (Clause 2.1.1)

• Oven dry samples at 103 ± 2°C until constant mass.
• Moisture % = (M1 - Mo) / Mo × 100
  • M1: Initial mass (g)
  • Mo: Oven-dry mass (g)

Test Setup (Clause 7.1)

• Use special jig (Fig. 2) to support specimens laterally during sustained load testing.
• Specimens and jig must be placed in the conditioning atmosphere.

flowchart LR
    A[Prepare Specimens] --> B[Apply Adhesive Uniformly]
    B --> C[Clamp Specimens (≥ 8 hrs at room temp)]
    C --> D[Release Clamps]
    D --> E[Conditioning Chamber]
    E --> F[25 ± 1°C, 65 ± 2% RH, ≥ 4 days]
    F --> G[Test Specimens with Jig]

This ensures standardized moisture and temperature conditions for reliable adhesive joint testing.

IS 4835: Testing Procedures for Strength – Key Points

1. Dry Strength (Clause 6.5.1)

• Test pieces: 10 samples prepared per Appendix F of IS 851-1978 using Canarium spp. veneers (density 0.5–0.9).
• Conditioning: As per Appendix D of IS 851-1978 at 27 ± 2°C and 65% RH.
• Test method: Appendix E of IS 851-1978.
• Requirement: Average failing load ≥ 300 kg.
• Wood failure at top joint: ≥ 85%.

2. Early Strength Development (Clause 6.6)

• Test pieces: 6 samples, prepared and conditioned similarly.
• Pressing: Under pressure for 2 hours at 27 ± 2°C and 65% RH.
• Requirement: Average failing load ≥ 60% of dry strength value (i.e., ≥ 180 kg).

3. Resistance to Sustained Load (Clause 6.10 & C-7.2)

• Setup: Top frame suspended; load applied to bottom frame.
• Measurement: Time to creep failure recorded automatically.

Summary Table:

flowchart TD
    A[Prepare Test Pieces (Appendix F)] --> B[Condition at 27 ± 2°C, 65% RH (Appendix D)]
    B --> C{Test Type}
    C -->|Dry Strength| D[Test at 300 kg load (Appendix E)]
    C -->|Early Strength| E[Press 2 hrs → Test at ≥60% dry strength]
    C -->|Sustained Load| F[Apply constant load → Record

IS 4835: Preparation of Test Specimens - Key Points

1. Moisture Content Determination (Clause 2.1.1)

• Drying: Oven dry samples at 103 ± 2°C until constant mass.
• Formula for Moisture Content:

[ \text{Percentage Moisture} = \frac{M_1 - M_0}{M_1} \times 100 ]

Where:

• (M_1) = Initial mass (g)
• (M_0) = Oven-dry mass (g)

2. Test Specimen Dimensions (Clause 12.5)

• Length: 115 ± 0.25 mm
• Width: 25 ± 0.3 mm
• Overlap joint: 12.5 ± 0.3 mm
• Specimen made from 3 slips of Canarium spp., Vateria indica, or Shorea assamica joined by adhesive.

3. Adhesive Preparation (Clause 4.1)

• Follow manufacturer instructions strictly.

Test Specimen with Double Lap Joint (Fig. 1)

flowchart LR
    A[Slip 1] ---|Overlap 12.5 mm| B[Slip 2]
    B ---|Overlap 12.5 mm| C[Slip 3]
    style A fill:#f9f,stroke:#333,stroke-width:2px
    style B fill:#ccf,stroke:#333,stroke-width:2px
    style C fill:#f9f,stroke:#333,stroke-width:2px

Summary: Ensure moisture content is controlled via oven drying, prepare specimens with precise dimensions, and apply adhesive as per manufacturer guidelines.

IS 4835: Mycological Tests for Resistance to Microorganisms

Key Points from IS 4835 & IS 851-1978:

• Test Specimen Dimensions (Clause 12.5):

  • Length: 115 ± 0.25 mm
  • Width: 25 ± 0.3 mm
  • Overlap joint: 12.5 ± 0.3 mm
  • Wood species: Canarium spp., Vateria indica, or Shorea assamica

• Test Method (Clause 6.5.2 & Appendix H, IS 851-1978):

  • Adhesive resistance to microorganisms is tested by exposing specimens to fungal or microbial cultures.
  • The test evaluates the adhesive's ability to withstand microbial degradation over a specified period.
  • The purchaser may specify the type of microorganism and exposure conditions.

• Dry Strength Requirement (Clause 6.5.1):

  • Average failing load of 10 specimens ≥ 300 kg
  • Wood failure at joint ≥ 85%
  • Conditioning: 27 ± 2°C, 65% RH

General Procedure for Mycological Resistance (from IS 851-1978 Appendix H):

Summary Diagram:

flowchart TD
    A[Prepare Specimens] --> B[Inoculate with Microorganisms]
    B --> C[Incubate under controlled conditions]
    C --> D[Inspect for fungal growth]
    D --> E{Pass/Fail}
    E -->|Pass| F[Adhesive Resistant]
    E -->|Fail| G[Adhesive Not Resistant]

Note: For detailed fungal species, incubation conditions, and evaluation criteria, refer to Appendix H of IS 851-1978. This test ensures adhesives maintain bond integrity in microbe-prone environments.