Code of practice for finishing wood and wood-based products with nitrocellulose and cold-catalyzed materials

IS 4597: Scope Summary

• Scope: Covers finishing of wood and wood-based products using nitrocellulose-based and cold catalysed materials (Clause 1.1).
• Definitions: Refer to IS 1303-1963 for finishing materials and IS 707-1958 for wood and related materials (Clause 2.1).
• Rounding Off: Final test or analysis values shall be rounded per IS 2-1960, retaining the same significant figures as specified values (Clause 0.5).
• International Coordination: The standard aligns with international practices while considering Indian field conditions (Clause 0.4).

Key References

Important Note on Rounding (IS 2-1960)

• Round off to the same number of significant figures as the specified value.
• Example: If specified value = 12.3 (3 significant digits), round measured value to 3 significant digits.

flowchart LR
    A[Wood & Wood Products] --> B[Nitrocellulose Finishing]
    A --> C[Cold Catalysed Finishing]
    B & C --> D[Testing & Analysis]
    D --> E[Rounding Off per IS 2-1960]

This ensures consistency and compliance in finishing quality evaluation.

IS 4597 - Definitions Key Points

• Clause 2.1: Definitions for finishing materials refer to IS 1303:1963 (Finishing materials terminology).
• Definitions related to wood and wood-based materials refer to IS 707:1958 (Wood and related materials terminology).

Important Notes:

• For rounding off test or analysis results, use IS 2:1960 guidelines on significant figures.
• The standard aligns with international practices while considering Indian conditions.

Summary Table of Reference Standards for Definitions

This ensures consistent terminology and measurement precision in structural finishing and wood-related works.

IS 4597: Necessary Information Summary

• Clause 2.1: Definitions for finishing materials refer to IS 1303-1963; for wood and related materials, refer to IS 707-1958.

• Clause 3 (Rounding off values):

  • Final test or analysis values must be rounded off per IS 2-1960.
  • The number of significant figures retained should match those in the specified standard values.

Key Points on Rounding (IS 2-1960):

• Maintain same decimal places/significant figures as specified values.

References for Further Details:

• IS 1303-1963: Finishing materials definitions
• IS 707-1958: Wood and related materials definitions
• IS 2-1960: Rules for rounding off numerical values

flowchart LR
    A[Test/Analysis Result] --> B{Round off per IS 2-1960}
    B -->|Digit < 5| C[Round Down]
    B -->|Digit ≥ 5| D[Round Up]
    C & D --> E[Final Value with same significant figures as standard]

This ensures consistency and accuracy in compliance evaluation.

IS 4597: Preparation of Wood for Finishing – Key Points

1. Necessary Information (Clause 3.2)

• Wood type & pretreatment: Preservation, seasoning affect finish.
• Usage location: Interior/exterior affects finish choice.
• Atmospheric conditions: Temperature & humidity impact drying & adhesion.
• Type of finish: Transparent, semi-transparent, or opaque finishes.

2. Preparation Steps (Clause 4.1)

• Sanding:
  • Use fine abrasive paper along the grain to avoid scratches.
  • Avoid cross-grain scratches or deep sanding marks; these cause dark stains.
  • For water stains, wet surface to raise grain, dry, then smooth.
• Recommended sanding methods: Machine sanding or belt sanding for uniformity.

3. Moisture Content (from related clauses)

• Maintain maximum permissible moisture content as per climatic zone for durability and finish adherence.

Summary Table: Sandpaper Grit for Wood Finishing

flowchart TD
    A[Wood Selection & Pretreatment] --> B[Check Moisture Content]
    B --> C[Consider Location & Climate]
    C --> D[Sanding (Along Grain)]
    D --> E[Wet Surface for Water Stain?]
    E -->|Yes| F[Raise Grain & Dry]
    E -->|No| G[Proceed to Finish Application]
    F --> G

Key references: IS 1303 (Finishing materials), IS 707 (Timber terms), IS 4597 clauses above.

IS 4597: Application of Filler - Key Points & Procedures

Purpose (Clause 5.1)

• Fillers fill pores and open cells of wood surfaces.
• Prevent excessive finish penetration.
• Provide a level, smooth surface for finishing.

Application Method (Clause 5.3)

• Apply filler using a rag pad in circular motions with pressure to force filler into pores.
• Alternatively, spray application followed by a mechanical mop to embed filler and remove excess.
• Number of coats depends on wood porosity.

Post-Application Handling (Clause 5.4)

• Wipe off excess filler within 5 to 10 minutes using a dry rag.

Overcoating (Clause 9.2)

• Filler can be applied over sealer or directly over filler.
• Application is usually by spray.
• Number of coats depends on the nonvolatile content of the filler material.

Summary Table: Application Steps

Visual Concept (Mermaid.js):

flowchart LR
    A[Wood Surface] --> B[Filler Application]
    B --> C{Method}
    C --> D[Rag Pad (Circular Pressure)]
    C --> E[Spray + Mechanical Mop]
    D & E --> F[Excess Filler Removal (5-10 mins)]
    F --> G[Sealer Application or Additional Filler Coats]
    G --> H[Final Finish]

This ensures a smooth, sealed wood surface ready for high-quality finishing.

IS 4597 - Sealing: Key Points & Specifications

• Primary Function (Clause 6.1):
  Prevents swelling/lifting of wood grains and bleeding of wood filler when finish is applied.
  Sealer coat(s) can be omitted if not essential, replaced by finish coat(s).

• Material & Application (Clause 6.2 & 9.2):

  • Sealer is nitrocellulose-based if final finish is nitrocellulose.
  • Applied by spray.
  • Number of coats depends on nonvolatile content of sealer or finishing material.
  • Can be applied directly over filler or over sealer.

• Nonvolatile Content & Coats:
  The number of coats is adjusted according to the nonvolatile content (%) of the sealer or finish. Higher nonvolatile content → fewer coats needed.

Typical Application Guidance (General Engineering Practice)

Summary Flow (Sealing Process)

flowchart TD
    A[Wood Surface Preparation] --> B[Apply Wood Filler]
    B --> C{Sealer Required?}
    C -- Yes --> D[Apply Nitrocellulose Sealer by Spray]
    C -- No --> E[Apply Finish Coat Directly]
    D --> E
    E --> F[Apply Finish Coats as per Nonvolatile Content]

References:

• IS 4597: Sealing and finishing of wood
• IS 1303: Definitions of finishing materials
• IS 707: Definitions related to wood and related materials

Key Specifications & Process for Levelling with Nitrocellulose Woodfiller (IS 4597)

1. Application:

• Use a transparent nitrocellulose-based woodfiller.
• Apply with a putty knife in straight strokes to ensure even coverage.

2. Drying:

• Air dry the woodfiller for 1 hour before sanding.

3. Sanding:

• Use '0' grade emery or flint paper for dry sanding.
• Take care not to cut through edges or corners.
• Remove dust by blowing off and wiping with a rag.

4. Additional Notes:

• If the sealer is uneven, levelling is done at this stage with the woodfiller.
• Pull over solution can be used to level nitrocellulose finish but may be skipped if burnishing/polishing is planned.
• Filler drying overnight and sanding with '0' grade paper is also recommended for final levelling.

Summary Table

flowchart TD
    A[Sealer Application] --> B{Uneven Surface?}
    B -- Yes --> C[Apply Nitrocellulose Woodfiller]
    C --> D[Air Dry 1 Hour]
    D --> E[Dry Sand with '0' Grade Paper]
    E --> F[Apply Nitrocellulose Finish]
    F --> G{Burnishing/Polishing?}
    G -- Yes --> H[Skip Pull Over Solution]
    G -- No --> I[Use Pull Over Solution to Level]

This ensures a smooth, level finish as per IS 4597 guidelines.

IS 4597 - Staining of Wood: Key Points & Specifications

1. Types of Stains (Clause 8.3)

• Water, Spirit, Naphtha, Acid resistant stains depending on requirements.
• Application methods: brushing, sponging, wiping, spraying.
• Stain should be thinned for liberal but even application without over-staining.

2. Application Guidelines

• Apply on flat surfaces first, then mouldings and edges to avoid double staining.
• On absorbent softwoods, apply evenly without overlapping.
• Spirit stains dry very quickly; apply swiftly and skillfully.
• Avoid staining damp wood with spirit stains to prevent dye precipitation.

3. Effects on Wood (Clause 8.2)

• Staining accentuates grain variations:
  • Hardwoods: Emphasizes porous springwood vs. dense summerwood.
  • Softwoods: Springwood absorbs more stain, reversing normal color sequence.

4. Spirit Stains (Clause 8.3.2)

• Composed of dyes dissolved in industrial methylated spirit.
• Penetrate softer wood parts without swelling fibers or raising grain.
• Dry quickly; suitable for finishing like water stains.

Summary Table

flowchart TD
    A[Start: Wood Surface Preparation] --> B{Type of Stain?}
    B -->|Water| C[Thin & Apply evenly]
    B -->|Spirit| D[Apply quickly on dry wood]
    B -->|Naphtha/Acid| E[Use as per resistance needs]
    C --> F[Flat surfaces first]
    D --> F
    E --> F
    F --> G[Edges and mouldings last]
    G --> H[Allow to dry]
    H --> I[Finish with clear coat]

Note: No explicit formulas or numeric tables for staining are given in IS 459

IS 4597: Application of Finish – Key Points

1. Necessary Information (Clause 3.2)

Efficient wood finishing requires knowledge of:

• Wood type & pretreatment (preservation, seasoning)
• Location of use (indoor/outdoor)
• Atmospheric conditions (temperature, humidity)
• Type of finish (e.g., nitrocellulose, two-pack lacquer)

2. Preparation of Wood (Clause 3.1)

• Surface texture influences finish quality.
• Wood species vary: hard/soft, resinous/porous.
• Proper surface preparation is essential for adhesion and durability.

3. Finish Function & Type (Clause 9.1)

• Finishes decorate and protect wood.
• Common finishes: nitrocellulose-based or two-pack materials (lacquer + activator).
• Two-pack finishes have limited pot life; mix only required quantity and use promptly.

Additional Notes (Engineering Practice)

• Moisture content of wood should be within permissible limits (refer IS: 1303 and IS: 707).
• Surface sanding grit size typically ranges from 180 to 220 for smooth finish.
• Application methods: brushing, spraying, or wiping depending on finish type.

flowchart TD
    A[Wood Type & Pretreatment] --> B[Surface Preparation]
    B --> C[Selection of Finish Type]
    C --> D[Application Method]
    D --> E[Finish Function: Decorate & Protect]

This summarizes the essentials for applying finishes per IS 4597.

IS 4597 – Pulling Over (Clauses 9 & 10) Key Points

• Purpose: Pulling over is used to level off the nitrocellulose finish for a smooth surface.

• Applicability:

  • Only for nitrocellulose finishes (Clause 10.1).
  • Can be skipped if burnishing/polishing follows.

• Process & Drying Times:

  • After final coat application, allow at least 24 hours aging (Clause 9.3).
  • Apply pull over solution, which leaves solvent in the finish.
  • Allow minimum 12 hours air drying before handling or packing (Clause 10.3).
  • Fixing fittings can be done during this drying period.

• Finishing: For best results, follow pulling over with polishing (Clause 10.4).

Summary Table

This ensures a smooth, durable finish with proper solvent evaporation and surface leveling.

IS 4597: Burnishing and Polishing Key Points

• Levelling (Clause 11.1):

  • Wet sand the film with 400 grade abrasive paper and soap water.
  • Sand along the grain, avoiding edges/corners cut-through.

• Burnishing (Clause 11.2):

  • Use a suitable burnishing compound applied by a pad for further surface leveling.

• Polishing (Clause 11.3 & 11.4):

  • Clean surface with a polishing compound applied along the grain using a pad.
  • Final rub with a soft lamb's wool mop on a flexible shaft polishing machine.
  • Small items can be polished on a stationary machine.
  • Avoid local overheating to prevent finish burning.

Summary Table

flowchart LR
    A[Levelling] --> B[Burnishing]
    B --> C[Polishing]
    C --> D[Final Gloss & Finish]

This sequence ensures a smooth, glossy, and defect-free surface as per IS 4597.