Specification for Synthetic Resin Adhesives for Plywood (Phenolic And Aminoplastic)
2006 Edition

IS 848 delineates the requirements for synthetic resin adhesives used in plywood manufacturing, including:

• Wood Moisture Content at Bonding: Optimal range typically 8-15% for effective adhesion.
• Surface Preparation: Wood surfaces must be clean, smooth, and devoid of dust, oils, or contaminants.
• Application Approach: Single or double glue spread depending on plywood type.
• Glue Quantity: Generally 150-250 g/m² per glue line, varying with resin type.
• Assembly Times:
  • Open Assembly: 5 to 15 minutes (time glue remains exposed before pressing).
  • Closed Assembly: 30 to 60 minutes (interval between assembly and pressing).
• Pressing Conditions:
  • Temperature: Between 120°C and 150°C.
  • Pressure: 10 to 15 kg/cm².
• Pressing Duration: Approximately 10 minutes per millimeter of thickness.
• Post-Processing: Conditioning plywood to stabilize moisture content.
• Cleaning: Use suitable solvents for equipment and container cleaning.

Rounding Protocol

• Test result values are rounded following IS 2:1960 to match the significant figures specified.

Illustrative Pressing Time Table

Process Flowchart

flowchart TD
    A[Wood Preparation] --> B[Adhesive Application]
    B --> C[Open Assembly Period]
    C --> D[Closed Assembly Period]
    D --> E[Pressing: Temperature & Pressure]
    E --> F[Post-Press Conditioning]

This section ensures plywood production adheres to IS 848 quality criteria.

IS 848 incorporates references to other standards that are integral to its provisions. Users should verify they are consulting the latest versions. Key points include:

• Adherence to the rounding rules from IS 2:1960 for numerical data.
• Definitions largely sourced from IS 707 and supplemented within IS 848.

Important Reference Standards

Rounding Rule (IS 2:1960)

• Final test or analytical results must be rounded to the same level of precision as the specified values.
• For example, a value specified as 12.3 should be rounded to one decimal place.

Reference Flowchart

flowchart LR
    A[IS 848] --> B[References Other IS Codes]
    B --> C[IS 2: Rounding Rules]
    B --> D[IS 707: Definitions]
    B --> E[Other Relevant Standards]

Summary: Always confirm the latest editions of referenced standards and apply IS 2 rounding consistently.

Definitions within IS 848 primarily align with those in IS 707:1976 (glossary for timber technology). Key aspects include:

• Rounding Off: Numerical test results must follow IS 2:1960 guidelines, maintaining the same significant figures as specified values, ensuring uniformity.

Overview Table

Notes

• Always verify timber-related definitions with IS 707.
• Use IS 2 for numerical result rounding to maintain standard conformity.

Terminology Flowchart

flowchart LR
    A[IS 848 Definitions] --> B[IS 707: Timber Glossary]
    A --> C[IS 2: Rounding Norms]
    B --> D[Standard Timber Terms]
    C --> E[Consistent Numerical Data]

This ensures clarity and consistency in interpreting timber and adhesive test specifications.

IS 848 categorizes adhesives based on their performance under cyclic testing conditions:

• Wood failure >75% (excellent), ≥50% (pass) | Suitable for exterior use; highly resistant to weather, boiling water, steam, and dry heat | | BWR | 3 cycles: 8-hour boiling + 16-hour drying at 65 ± 2°C | - No ply delamination post 3 cycles
• Wood failure >75% (excellent), ≥50% (pass) | Resistant to weather for a few years; cold water indefinitely; limited boiling water exposure | | MR | 3 cycles: 3-hour water soaking at 60 ± 2°C + 8-hour drying at 65 ± 2°C | - No ply delamination post 3 cycles
• Wood failure >75% (excellent), ≥50% (pass) | Suitable for interior use; withstands cold water long-term, limited hot water; fails in boiling water |

Notes:

• Wood failure indicates wood breaks before adhesive bond, demonstrating strong adhesion.
• Adhesives must be stored and used within shelf-life as per manufacturer instructions.
• Testing simulates environmental exposure through cyclic boiling and drying.

Classification Flow Diagram

flowchart LR
    A[Adhesive Classification] --> B{Test Cycles}
    B -->|6 cycles| C[BWP]
    B -->|3 cycles| D[BWR]
    B -->|3 cycles| E[MR]
    C --> F[High durability, exterior applications]
    D --> G[Moderate durability, limited boiling exposure]
    E --> H[Interior use, moisture resistant]

This classification assists in selecting adhesives suited to plywood durability and environmental resistance requirements.

The quality parameters for resin adhesives are detailed in Clause 5 of IS 848, summarizing keeping qualities:

• Wood failure >75% (excellent), ≥50% (pass) | High resistance to weather, boiling water, steam, dry heat | | BWR | 3 cycles: 8h boiling + 16h drying at 65 ± 2°C | - No ply separation after 3 cycles
• Wood failure >75% (excellent), ≥50% (pass) | Suitable for weather exposure over years; withstands cold water indefinitely; limited boiling water exposure | | MR | 3 cycles: 3h water soaking at 60 ± 2°C + 8h drying at 65 ± 2°C | - No ply separation after 3 cycles
• Wood failure >75% (excellent), ≥50% (pass) | Suitable for long-term cold water exposure; limited hot water use; not suitable for boiling water |

Additional Information:

• Adhesives must meet criteria after storage per manufacturer instructions.
• Testing involves forced ply separation using a knife; wood failure percentage reflects bond strength.
• Film and powder adhesives follow similar quality and storage requirements.

Summary Table (Markdown Format)

| Type | Test Cycles | Temperature & Duration | Wood Failure Threshold | Typical Application |
|------|-------------|-----------------------|-----------------------|---------------------|
| BWP  | 6 cycles    | 8h boiling + 16h drying @ 65 ± 2°C | >75% excellent, ≥50% pass | Exterior, highly durable |
| BWR  | 3 cycles    | 8h boiling + 16h drying @ 65 ± 2°C | >75% excellent, ≥50% pass | Weather resistant, limited boiling |
| MR   | 3 cycles    | 3h soaking @ 60 ± 2°C + 8h drying @ 65 ± 2°C | >75% excellent, ≥50% pass | Moisture resistant, not for boiling water |

IS 848 specifies detailed guidelines for the preparation and application of synthetic resin adhesives:

1. Manufacturer's Written Guidelines (Clause 6.1)

• Comprehensive instructions must be provided including resin and hardener ratios, addition of fillers, extenders, or fortifiers.
• Preparation (Clause 6.3) and application procedures (Clause 6.5) must be clearly outlined.

2. Preparation Procedures (Clause 6.3)

• Accurate measurement of resin, hardener, and additives.
• Proper mixing techniques and recommended equipment.
• Precautions to prevent contamination and ensure uniformity.

3. Application Parameters (Clause 6.5)

Pressing Time Calculation

[ t = k \times \text{thickness (mm)} ]

• Where t = pressing time in minutes
• k = constant (~1.5 min/mm depending on resin type)

Process Flow Diagram

flowchart TD
    A[Resin & Hardener] --> B[Mixing as per instructions]
    B --> C[Add Filler, Fortifier, Extender]
    C --> D[Prepare Wood Surface]
    D --> E[Apply Adhesive (Single/Double Spread)]
    E --> F[Assemble within Open Assembly Time]
    F --> G[Press at Specified Temperature & Pressure]
    G --> H[Maintain Pressing Time]

IS 848 outlines specific test methods to evaluate adhesive performance:

• Test Specimens: Prepared according to Clause 7.3.2 and tested under cyclic conditions described in Table 1.
• Conformity Criteria: Defined in Table 1 to ensure minimum performance standards are met.
• Result Rounding: Test outcomes must be rounded as per IS 2:1960, maintaining the specified number of significant digits.
• Adhesion Testing: Conducted following IS 848 Part 5 (1983 revision) to verify bonding strength.

Summary of Test Schedule (Table 1)

Rounding Rule (IS 2:1960)

• If the digit following the last significant figure is ≥5, round up; otherwise, round down.

Testing Flowchart

flowchart LR
    A[Test Specimen] --> B{Test Type}
    B -->|BWP| C[Boiling Water Cyclic Test]
    B -->|BWR| D[Boiling Water Cyclic Test]
    B -->|MR| E[Moisture Cyclic Test]
    C & D & E --> F[Assess Delamination]
    F --> G{Meets Criteria?}
    G -->|Yes| H[Passes Test]
    G -->|No| I[Fails Test]

Refer to Clause 7.3.2 and Table 1 of IS 848 for detailed procedures.

According to Clause 7.3.4 and Table 1, adhesive specimens must satisfy the following conformity standards:

• Testing per Clauses 7.3.2 & 7.3.3 must meet the acceptance criteria specified.
• Rounding of test data should comply with IS 2:1960, retaining the same significant figures as the standard values.
• Resin adhesives are required to fulfill performance specifications pertinent to their classification.

Summary Table of Conformity Criteria

Note: Refer to full IS 848 Table 1 for exact numerical values and detailed testing conditions.

Rounding Protocol (IS 2:1960)

• Round final results to the same number of significant digits as the specified value.
• Example: A specified value of 2.50 (three significant digits) requires rounding test results accordingly.

Conformity Flowchart

flowchart LR
    A[Test Specimen] --> B[Testing per Clauses 7.3.2 & 7.3.3]
    B --> C{Meets Table 1 Criteria?}
    C -- Yes --> D[Conforms with IS 848]
    C -- No --> E[Reject or Retest]

Summary: Ensure all test results comply with Table 1 criteria, apply IS 2 rounding rules, and confirm adhesive compliance.

Per Clause 9.1, every container of plywood or adhesive must bear clear, permanent markings including:

• Manufacturer’s identity or distinctive mark
• Material description
• Batch or lot number
• Manufacturing date
• Expiry date for adhesive components (storage as per manufacturer’s recommendations)
• Reference to the manufacturer's instructions
• Statement: "To be stored in a cool dry place"

BIS Standard Mark (Clause 9.1.1)

• Use of the Standard Mark follows the Bureau of Indian Standards Act, 1986.
• Licensing for the Standard Mark is managed through BIS.

Adhesive Keeping Qualities (Clause 5 Summary)

Marking Components Diagram

graph LR
A[Container] --> B[Manufacturer’s Name/Mark]
A --> C[Material Description]
A --> D[Batch Number]
A --> E[Manufacture Date]
A --> F[Expiry Date]
A --> G[Reference to Instructions]
A --> H["To be stored in a cool dry place"]

Note: Adhere strictly to manufacturer’s storage and usage instructions to maintain adhesive performance and compliance.

IS 848 details the procedure for preparing test pieces under Clauses 7.2, 7.3.1, and 6.3:

• Specimen Preparation (Clause 7.2 & Annex A):

  • Test specimens must be fabricated following Annex A instructions.
  • Veneers should comply with Annex A-1 criteria regarding quality, thickness, and moisture content.

• Specimen Preparation (Clause 7.3.1):

  • Strict adherence to Clause 7.2 ensures uniform specimen quality.

• Material Preparation (Clause 6.3):

  • Resin, hardener, fortifier, filler, and extender must be prepared and blended as prescribed.
  • Use recommended mixing equipment and avoid contamination or curing issues.

• Conformity Requirements (Clause 7.3.2 & Table 1):

  • Specimens must achieve strength and quality benchmarks outlined in Table 1 (e.g., tensile and shear strength).

Summary of Preparation Steps

Typical Test Piece Dimensions

Preparation Workflow

flowchart TD
    A[Select Veneers] --> B[Prepare Resin Mix]
    B --> C[Mix Components Thoroughly]
    C --> D[Mould and Press]
    D --> E[Cure Under Specified Conditions]
    E --> F[Cut Test Specimens]
    F --> G[Conduct Testing per IS 848]

Note: Always comply with IS 848 preparation procedures to ensure test validity.

IS 848 Annex B (Clause 7.4) specifies the method for determining the pH of cured resin adhesives:

• The pH value of cured adhesive must be ≥ 2.0.
• Use distilled water exclusively for mixing.
• Prepare a minimum of 100 g adhesive following manufacturer instructions.

Procedure Summary

Important Notes

• Ensure pH meter calibration for accuracy.
• Maintain consistent adhesive film thickness.
• Follow curing and pressing conditions as per resin manufacturer.

Procedure Flowchart

flowchart TD
    A[Prepare 100 g Adhesive] --> B[Stir Thoroughly]
    B --> C[Spread 0.5 mm Film on Glass]
    C --> D[Cure as Specified]
    D --> E[Peel and Grind Film (<450 micron)]
    E --> F[Mix 2 g Powder + 10 ml Distilled Water]
    F --> G[Store Stoppered 72 hrs]
    G --> H[Measure pH]
    H --> I{pH Change ≤ 0.05?}
    I -- No --> G
    I -- Yes --> J[Record Equilibrium pH]

This method facilitates accurate pH measurement to ensure adhesive quality per IS 848.