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

IS 848: Scope & Key Specifications Summary

IS 848 covers synthetic resin adhesives for plywood manufacturing with detailed guidance on:

• Moisture Content at Gluing: Typically 8-15% for wood to ensure proper adhesion.
• Surface Preparation: Wood surfaces must be clean, smooth, and free from dust, oil, or contaminants.
• Application Method: Single or double glue spread depending on plywood type.
• Glue Spread Amount: Usually 150-250 g/m² per glue line (varies by resin type).
• Assembly Times:
  • Open assembly time: 5-15 minutes (max time glue remains exposed before pressing).
  • Closed assembly time: 30-60 minutes (time between assembly and pressing).
• Pressing Conditions:
  • Temperature: 120°C to 150°C.
  • Pressure: 10-15 kg/cm².
• Pressing Time: Approx. 10 minutes per mm thickness.
• Post-Treatment: Conditioning of plywood to stabilize moisture content.
• Cleaning: Use appropriate solvents to clean containers and equipment.

Rounding Off Values

• Follow IS 2:1960 for rounding test results to the same significant figures as specified.

Example Table: Pressing Time vs Thickness

flowchart TD
    A[Wood Preparation] --> B[Glue Application]
    B --> C[Open Assembly Time]
    C --> D[Closed Assembly Time]
    D --> E[Pressing (Temp & Pressure)]
    E --> F[Post Treatment]

This concise scope ensures quality plywood production per IS 848.

IS 848 References: Key Points

• IS 848 refers to other standards as integral parts of its provisions; users should check the latest editions for updates.
• Rounding off results must follow IS 2:1960 rules, maintaining the same number of significant figures as specified.
• Definitions primarily refer to IS 707 and additional definitions within IS 848.

Important Reference Standards in IS 848:

Rounding Off Rule (from IS 2:1960):

• Final test or analysis values must be rounded to the same decimal place/significant figure as the standard value.
• Example: If a value is specified as 12.3, round off to one decimal place.

flowchart LR
    A[IS 848 Standard] --> B[References other IS codes]
    B --> C[IS 2: Rounding off rules]
    B --> D[IS 707: Definitions]
    B --> E[Other material/test standards]

Summary: Always verify referenced standards for the latest edition and apply IS 2 rounding rules consistently for compliance.

IS 848: Definitions Summary

• Reference Standard: Definitions primarily follow IS 707: 1976 (Glossary of terms for timber technology and utilization).

• Rounding Off: Final test or calculation values must be rounded per IS 2: 1960:

  • Retain the same number of significant figures as the specified value.
  • Ensures consistency in reporting.

Key Points:

Practical Note:

• Always cross-check timber-related terms with IS 707.
• Use IS 2 rules for rounding numerical results to maintain standard compliance.

flowchart LR
    A[IS 848 Definitions] --> B[IS 707: Timber Terms]
    A --> C[IS 2: Rounding Rules]
    B --> D[Standard Timber Terminology]
    C --> E[Consistent Numerical Values]

This ensures clarity and uniformity in timber testing and specification interpretation.

IS 848: Classification of Adhesives (Key Summary)

Important Notes:

• Wood failure means the wood breaks before adhesive bond fails, indicating strong adhesion.
• Adhesives must be stored as per manufacturer's instructions and tested within shelf life.
• Tests involve cyclic boiling and drying to simulate environmental exposure.

This classification ensures selection of appropriate adhesive for durability and environmental resistance in plywood and wood products.

flowchart LR
    A[Adhesive Type] --> B{Test Cycles}
    B -->|6 cycles| C[BWP]
    B -->|3 cycles| D[BWR]
    B -->|3 cycles| E[MR]
    C --> F[Highly resistant to boiling water, weather, steam]
    D --> G[Moderate resistance, limited boiling water exposure]
    E --> H[Resistant to moisture, fails in boiling water]

IS 848: Quality of Resin Adhesives - Key Specifications

Keeping Qualities of Resin Adhesives (Clause 5)

Additional Notes:

• Adhesives must meet requirements after storage as per manufacturer's instructions.
• Testing involves forcible ply separation with a knife; wood failure percentage indicates bond quality.
• Film/Powder adhesives have similar storage and testing requirements.

Summary Table (Markdown)

| Type | Test Cycles | Temperature & Duration | Wood Failure Criteria | Use Case |
|-------|-------------|-----------------------|----------------------|----------|
| BWP | 6 cycles | 8h boiling + 16h drying @ 65 ± 2℃ | >75% excellent, ≥50% pass | Highly durable, boiling water proof |
| BWR | 3 cycles | 8h boiling + 16h drying @ 65 ± 2℃ | >75% excellent, ≥50% pass | Weather resistant, limited boiling water |
| MR | 3 cycles | 3h @ 60 ± 2℃ water + 8h drying @ 65 ± 2℃ | >75% excellent, ≥50% pass | Moisture resistant, fails boiling water |

IS 848: Instructions for Use - Key Points & Specifications

1. Manufacturer's Written Instructions (Clause 6.1)

• Detailed usage for each resin or resin combination with hardener, filler, fortifier, extender.
• Must cover preparation (Clause 6.3) and application (Clause 6.5).

2. Preparation for Use (Clause 6.3)

• Mixing ratios of resin, hardener, fillers.
• Mixing methods and apparatus.
• Precautions during mixing.

3. Application Guidelines (Clause 6.5)

Typical Pressing Time Formula

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

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

Summary Diagram: Resin Preparation & Application Flow

flowchart TD
    A[Start: Resin & Hardener] --> B[Mixing as per instructions]
    B --> C[Add fillers, fortifiers, extenders]
    C --> D[Prepare wood surface]
    D --> E[Apply glue (single/double spread)]
    E --> F[Assemble within open assembly time]
    F --> G[Press at recommended pressure & temperature]
    G --> H[Maintain pressing time]

IS 848: Test Methods - Key Points

• Test Specimens: As per Clause 7.3.2, specimens must be tested following the schedule in Table 1 under cyclic test conditions for BWP (Boiling Water Proof), BWR (Boiling Water Resistant), or MR (Moisture Resistant) plywood types.

• Criteria of Conformity: Table 1 defines the acceptance criteria for test results, ensuring specimens meet minimum performance standards.

• Rounding Off Results: Final test values must be rounded according to IS 2:1960. The number of significant figures in the rounded result should match the specified value’s precision.

• Adhesion Test: Adhesion of plies is tested as per the method in IS 848 Part 5 (1983 second revision), ensuring bonding quality.

Table 1 (Summary of Test Schedule & Criteria)

Important Formula:

• Rounding rule (IS 2:1960):
  If the digit after the last significant figure is ≥5, round up; else round down.

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[Evaluate Delamination]
    F --> G{Criteria Met?}
    G -->|Yes| H[Specimen Passes]
    G -->|No| I[Specimen Fails]

For detailed test procedures, refer to IS 848 Clause 7.3.2 and Table 1.

IS 848: Criteria of Conformity (Clause 7.3.4 & Table 1)

• Specimen Testing: Specimens tested as per Clauses 7.3.2 & 7.3.3 must meet the conformity criteria in Table 1.
• Rounding Off: Final test values must be rounded per IS 2:1960, retaining the same significant figures as the specified values.
• Adhesive Compliance: Resin adhesives must meet specified standards relevant to their type.

Table 1: Criteria of Conformity (Summary)

Note: Exact numerical values and detailed test conditions are in the full IS 848 Table 1.

Key Formula: Rounding Off (IS 2:1960)

• Round final test value to same significant figures as specified value.
• Example: Specified value = 2.50 (3 significant figures), test result = 2.496 → Rounded to 2.50.

flowchart LR
    A[Test Specimen] --> B[Test as per 7.3.2 & 7.3.3]
    B --> C{Meets Criteria in Table 1?}
    C -- Yes --> D[Conforms to IS 848]
    C -- No --> E[Reject/Retest]

Summary: Ensure test results meet Table 1 criteria, round values per IS 2:1960, and verify adhesive compliance for conformity.

IS 848: Marking and Labeling Requirements (Clause 9.1)

Each container of plywood or adhesive must be legibly and indelibly marked with:

• Manufacturer's name or distinguishing mark
• Description of material
• Batch number
• Date of manufacture
• Expiry date for adhesive components (storage as per manufacturer's recommendation)
• Reference to manufacturer's instructions
• The phrase: "To be stored in a cool dry place"

BIS Standard Mark (Clause 9.1.1)

• Use of the Standard Mark is governed by the Bureau of Indian Standards Act, 1986.
• Licensing details for the Standard Mark are available from BIS.

Adhesive Keeping Qualities (Summary Table from Clause 5)

Summary Diagram: Marking Components

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

Note: Always follow manufacturer's instructions for storage and use to ensure adhesive performance and compliance.

IS 848: Method of Preparation of Test Pieces (Clauses 7.2, 7.3.1, 6.3)

• Test Pieces Preparation (Clause 7.2 & Annex A):

  • Test pieces must be prepared as per Annex A instructions.
  • Veneers used must comply with Annex A-1 specifications (quality, moisture content, thickness).

• Specimen Preparation (Clause 7.3.1):

  • Follow the preparation method in Clause 7.2 strictly to ensure uniformity.

• Material Preparation (Clause 6.3):

  • Resin, hardener, fortifier, filler, and extender must be prepared and mixed according to prescribed methods.
  • Use recommended mixing apparatus and follow precautions to avoid contamination or improper curing.

• Conformity Criteria (Clause 7.3.2 & Table 1):

  • Test specimens must meet strength and quality criteria listed in Table 1 (e.g., tensile strength, shear strength).

Key Preparation Steps (Summary)

Typical Test Piece Dimensions (from Annex A)

flowchart TD
    A[Select Veneers] --> B[Prepare Resin Mix]
    B --> C[Mix Components]
    C --> D[Moulding & Pressing]
    D --> E[Curing]
    E --> F[Cut Test Specimens]
    F --> G[Test as per IS 848]

Note: Always

Determination of pH Value of Resin Adhesives (IS 848 - Annex B, Clause 7.4)

Key Specifications:

• pH of cured adhesive ≥ 2.0.
• Use distilled water only for mixing.
• Adhesive preparation: minimum 100 g as per manufacturer's instructions.

Procedure Summary:

Important Notes:

• pH meter must be calibrated.
• Maintain uniform adhesive thickness.
• Follow resin manufacturer's curing and pressing conditions.

flowchart TD
    A[Prepare 100g adhesive] --> B[Stir thoroughly]
    B --> C[Spread 0.5mm film on glass]
    C --> D[Cure per manufacturer]
    D --> E[Peel & grind film (<450 micron)]
    E --> F[Weigh 2g powder + 10ml distilled water]
    F --> G[Stir & store stoppered 72h]
    G --> H[Measure pH]
    H --> I{pH change ≤ 0.05?}
    I -- No --> G
    I -- Yes --> J[Equilibrium pH value]

This method ensures accurate and reproducible pH determination of resin adhesives per IS 848.