Critical for identification of commercial timbers

IS 4970: Scope Summary

IS 4970 provides a diagnostic key for identification of commercial timbers used by purchasing departments (railways, defense), timber trade, and industry.

Key Points:

• Covers 60 species of commercial timbers (40 original + 20 added in revision).
• Focuses on general and anatomical diagnostic features for timber identification.
• Intended for field use to verify timber species supplied.
• Requires users to have basic knowledge of wood structure and physical properties.
• Accompanied by illustrated handbook: Field identification of fifty important timbers of India (recommended study material).

Features included in the key:

• Porosity (Non-porous, ring-porous, size of pores)
• Growth rings prominence
• Colour (sapwood and heartwood distinction)
• Hardness and weight categories
• Anatomical features like radial canals, phloem, ripple marks

Typical classification table snippet:

This standard aids accurate timber species identification essential for quality control and procurement in commercial timber usage.

IS 4970: Tools & Equipment for Timber Identification

• Punched Cards:

  • Size: 145 x 115 mm
  • Diagnostic features (Table 1) are notched using scissors/clippers (Fig. 2).
  • Cards include trade & botanical timber names.

• Identification Method:

  • Use the punched cards to notch features like pore size, growth rings, color, hardness, and weight.
  • Features correspond to codes in Table 1 (e.g., pore size: non-porous (28), ring-porous (29), etc.).
  • This system helps identify timber species quickly in the field.

• Key Features in Table 1 (Excerpt):

• Tools:
  • Scissors or clippers for notching cards.
  • Reference handbook: Field Identification of Fifty Important Timbers of India by K.R. Rao & K.B.S. Juneja.

flowchart LR
    A[Timber Sample] --> B[Observe Diagnostic Features]
    B --> C[Match Features on Punched Card]
    C --> D[Notch Corresponding Features]
    D --> E[Identify Timber Species]

Summary: IS 4970 uses a punched card key system with specific diagnostic features notched for timber identification, supported by a handbook and simple tools like scissors.

IS 4970: Definitions of Diagnostic Features for Timber Identification

Key Points from IS 4970:

• Clause 3.0: Defines general and anatomical diagnostic features used in timber identification.
• Clause 4.1 & Table 1: Lists diagnostic features of 60 commercial timbers, indicating presence or variability of features.
• Clause 3.63: Example - Gum or Resin Streaks, Prominent: vertical canals visible as reddish-brown gummy streaks on longitudinal surfaces (e.g., chir, kail, pine).
• Diagnostic Features Categories:
  • Porosity: Non-porous, ring-porous, large to very small pores.
  • Pore Arrangement: Solitary, radial multiples, tangential clusters.
  • Growth Rings: Prominent or abrupt transition from early to latewood.
  • Color & Hardness: Sapwood/heartwood distinction, color shades, hardness levels.
  • Other Features: Included phloem, ripple marks, resin streaks.

Typical Diagnostic Feature Table Extract (Simplified):

Usage Tips:

• Identification cards (145x115 mm) are used for field identification.
• Basic knowledge of wood anatomy is essential.
• Recommended reading: Field Identification of Fifty Important Timbers of India by K. Ramesh Rao & K. B. S. Juneja.

flowchart TD
    A[Start: Timber Sample] --> B{Check Porosity}
    B -->|Non-Porous| C[Check Pore Size & Arrangement]
    B -->|Ring-Porous| C
    C --> D{Observe Growth Rings}
    D -->

IS 4970 - Diagnostic Features of Commercial Timbers

The standard provides diagnostic features for 60 common commercial timbers in Table 1. Each timber species is identified by a set of numbered features representing anatomical, physical, and visual characteristics.

Key Points:

• Features are coded by numbers (e.g., 1, 3, 4, 9, etc.) corresponding to specific diagnostic traits such as:
  • Pore size and distribution (non-porous, ring-porous)
  • Color (light, yellow, brown shades, red shades)
  • Hardness (soft to very hard)
  • Weight (light to very heavy)
  • Presence of anatomical features like radial canals, included phloem, ripple marks, growth rings
• Some timbers require multiple "cards" due to variability in features.
• Example:
  • Aini (Artocarpus hirsutus): Features 1,3,4,9,12,15,20,23,27,30,31,33,37,43,49,50
  • Chir (Pinus roxburghii): Features 1,4,5,9,12,14,19,24,26,28,55,56,61,63

Usage:

• The features help in field identification by matching observed wood characteristics.
• Users should be familiar with wood anatomy and properties.
• Recommended reference: Field identification of fifty important timbers of India by K. Ramesh Rao & K.B.S. Juneja.

Sample Diagnostic Feature Codes (from Table 1):

Summary Diagram (Identification Process):

flowchart TD
    A[Start: Sample Timber] --> B[Observe Anatomical Features]
    B

IS 4970: Preparation of Identification Cards for Timber

Key Points from IS 4970:

• Set of Punched Cards (Clause 2.6 & 5.1):

  • Cards represent diagnostic features of timbers.
  • Features are notched on cards using scissors/clippers (Fig. 2).
  • Each card is labeled with trade and botanical names in the center.

• Diagnostic Features (Clause 4.1):

  • Table 1 lists features for 60 common commercial timbers.
  • Features in brackets indicate variable presence; such timbers may have multiple cards.

• Method of Use (Clause 6.1):

  • Cards are used as a key by sequentially matching notches to timber features (6.1.1 to 6.1.7).

Summary Table (Conceptual)

Visual Concept (Mermaid.js)

flowchart TD
    A[Start: Identify Timber] --> B[Select Card(s) from Set]
    B --> C[Notch Diagnostic Features]
    C --> D[Label Card with Names]
    D --> E[Use Card Key to Identify Timber]
    E --> F{Match Features?}
    F -- Yes --> G[Timber Identified]
    F -- No --> B

Note: Refer to Table 1 in IS 4970 for detailed diagnostic features per timber species.

Method of Using the Identification Key (IS 4970)

IS 4970 provides a systematic key for identifying commercial timbers based on diagnostic features—both general and anatomical.

Key Points:

• Basic Knowledge Required: Users should understand wood structure and physical properties.
• Diagnostic Features: Include pore size/type, growth rings, color, hardness, weight, and anatomical details like radial canals, phloem, and pore arrangements.
• Stepwise Identification: The key uses a decision tree approach, starting from broad features (e.g., pore size: non-porous, ring-porous) narrowing down to specific species.
• Punched Cards: A physical tool (145 x 115 mm cards) is provided for quick reference.
• Reference Handbook: Recommended to study "Field Identification of Fifty Important Timbers of India" for detailed understanding.

Example Table Extract (Simplified)

Identification Flow (Simplified Mermaid.js Diagram)

graph TD
A[Start: Observe Timber] --> B{Pore Type?}
B -->|Non-porous| C{Pore Size?}
B -->|Ring-porous| D{Growth Rings?}
C --> E[Color]
D --> E
E --> F[Hardness]
F --> G[Weight]
G --> H[Identify Timber Species]

Summary: Use the key by observing timber features in sequence—pore characteristics, color, hardness, weight—consulting punched cards or tables to narrow down the species. Study the recommended handbook for detailed anatomical knowledge to improve accuracy.

IS 4970 - Notes on Timber Sample Examination: Key Points

1. Diagnostic Features (Clause 4.1 & Table 1)

• Diagnostic features of 60 common commercial timbers are tabulated.
• Features in brackets indicate partial or occasional presence.
• Features include:
  • Porosity (Non-porous, Ring-porous)
  • Pore size (Very large to scanty)
  • Growth ring prominence
  • Colour (Light, Yellow, Brown shades, Red shades, others)
  • Hardness (Soft to very hard)
  • Weight (Light to moderately heavy)
  • Anatomical features like radial canals, included phloem, ripple marks.

2. Preparation of Identification Cards (Clause 5.1)

• Cards (145 x 115 mm) are notched to represent diagnostic features.
• Each timber species has a set of cards with specific feature notches.
• Trade and botanical names are marked on cards.

3. Method of Use (Clause 6.1.2)

• Identify a distinctive feature in the unknown timber.
• Insert a needle through the corresponding hole in the card pack.
• Shake the pack; cards with the feature fall out, narrowing the species.

Summary Table (Excerpt of Diagnostic Features)

Visual Concept: Identification Process

flowchart TD
    A[Examine Timber Sample] --> B[Identify Distinctive Feature]
    B --> C[Insert Needle in Card Pack Hole]
    C --> D[Shake Card Pack]
    D --> E[Cards with Feature Fall Out]
    E --> F[Identify Timber Species]

References for deeper study:

• "Field Identification of Fifty Important Timbers of India" by K.R. Rao & K.B.S. Juneja
• Forest Research Institute & Colleges, Dehra

IS 4970 primarily provides a key for identification of commercial timbers rather than structural design formulas or direct precautions/limitations. However, based on timber engineering principles and typical IS code guidance, here are key precautions and limitations for timber use:

Precautions and Limitations for Timber (General IS Practice)

• Moisture Content: Ensure timber moisture content is controlled (usually 12-15%) to prevent shrinkage, swelling, or decay.
• Species Identification: Use correct species as per IS 4970 key to ensure expected mechanical properties.
• Defects: Avoid timber with knots, splits, or decay as these reduce strength.
• Load Limitations: Timber is anisotropic; design for bending, shear, and compression using IS 883 or IS 1734.
• Durability: Protect against termites, fungi, and weathering by treatment or design detailing.
• Fire Resistance: Timber is combustible; provide fire retardant treatment or protective cladding.

Common Design Formulas (from IS 883 / IS 1734)

• Bending Stress, ( \sigma_b ): [ \sigma_b = \frac{M}{Z} ] where (M) = bending moment, (Z) = section modulus.

• Shear Stress, ( \tau ): [ \tau = \frac{V}{A} ] where (V) = shear force, (A) = cross-sectional area.

Summary Table: Timber Properties (Typical)

flowchart LR
    A[Timber Selection] --> B[Species Identification (IS 4970)]
    B --> C[Moisture Control]
    C --> D[Defect Check]
    D --> E[Design Calculations (IS 883)]
    E --> F[Protection Measures]
    F --> G[Installation & Maintenance]

Note: For detailed mechanical