Museum plywood -Specification

IS 15791 - Scope Summary

IS 15791 covers specifications and test methods for plywood and wood-based panel products, including formaldehyde emission measurement.

Key Points on Scope:

• Rounding Off Values: Final test or analysis results must be rounded per IS 2:1960, retaining the same significant figures as specified.
• Certification Marking: Use of the BIS Standard Mark follows the BIS Act, 1986 and related rules (Clause 11.2.1).
• Referenced Standards: Includes standards on plywood types, test methods, and terminology, e.g.:
  • IS 303: Plywood for general purposes
  • IS 1734 (Part 1): Density and moisture content tests
  • IS 707: Timber technology glossary
  • IS 5509: Fire retardant plywood
  • IS 710: Marine plywood
  • IS 5539: Preservative treated plywood

Formaldehyde Emission Measurement (Annex B):

• Desiccator Method: Formaldehyde emitted is absorbed in distilled water.
• Detection: Reacts with chromotropic acid-sulphuric acid to form a purple chromogen.
• Quantification: Absorbance measured by spectrophotometer; concentration derived from a calibration curve.

Rounding Off Rule (per IS 2:1960):

flowchart LR
    A[Sample] --> B[Formaldehyde Emission]
    B --> C[Absorbed in Distilled Water]
    C --> D[React with Chromotropic Acid + H2SO4]
    D --> E[Purple Chromogen Formation]
    E --> F[Spectrophotometer Absorbance]
    F --> G[Calculate Formaldehyde Concentration]

This scope ensures quality control for plywood products, emphasizing test accuracy and formaldehyde safety.

IS 15791 - References: Key Points & Tables

1. Referenced Standards (Clause 2):
   IS 15791 incorporates provisions from these key Indian Standards (IS):

   IS No.	Title
   303:1989	Plywood for general purposes - Specification
   707:1976	Glossary of timber technology terms
   710:1976	Specification for marine plywood
   1734 (Part 1):1983	Test methods for plywood: density & moisture content
   5509:2000	Fire retardant plywood - Specification
   5539:1969	Preservative treated plywood - Specification

2. Rounding Off Values:
   Follow IS 2:1960 for rounding test/analysis results, retaining significant figures as per the specified value.

3. Formaldehyde Emission - Desiccator Method (Annex B):

   • Formaldehyde emitted is absorbed in distilled water.
   • Reacted with chromotropic acid-sulphuric acid forming purple chromogen.
   • Absorbance measured by spectrophotometer.
   • Concentration determined from calibration curve of standard formaldehyde solutions.

4. Certification Marking (Clause 11.2.1):
   Use of BIS Standard Mark governed by BIS Act 1986; licensing details available from BIS.

Summary Diagram of Formaldehyde Measurement (Desiccator Method)

flowchart LR
    A[Product Sample] --> B[Placed in Desiccator]
    B --> C[Formaldehyde Emission]
    C --> D[Absorbed in Distilled Water]
    D --> E[React with Chromotropic Acid + H2SO4]
    E --> F[Purple Chromogen Formation]
    F --> G[Measure Absorbance (Spectrophotometer)]
    G --> H[Determine Concentration via Calibration Curve]

This concise overview helps in navigating IS 15791 references and related test methods effectively.

IS 15791 - Definitions Summary

• Reference for Definitions:
  All definitions in IS 15791 refer to IS 707: Glossary of terms applicable to timber technology and utilization (1976).

• Rounding Off Values:
  Final test or analysis values must be rounded off as per IS 2: 1960 rules, keeping the same significant digits as the specified values.

• Key Related Standards:

  IS No.	Title
  707 : 1976	Glossary of terms for timber technology
  303 : 1989	Plywood for general purposes - Specification
  1734 (Part 1) : 1983	Methods of test for plywood - Density & moisture content

• BIS Certification Marking:
  Governed by the Bureau of Indian Standards Act, 1986 (Clause 11.2.1).

Important Note on Formaldehyde Emission (Annex B)

• Desiccator Method Formula:

  [ \text{Formaldehyde emitted (mg)} = x \times 0.15 ]

  where (x) = volume (ml) of sodium thiosulphate solution used in titration.

Summary Diagram: Definition Reference Flow

flowchart TD
    A[IS 15791 Definitions] --> B[Refer IS 707 Glossary]
    A --> C[Follow IS 2 for rounding off]
    A --> D[Related Standards: IS 303, IS 1734]
    A --> E[BIS Certification per BIS Act 1986]

For detailed definitions, consult IS 707 directly.

IS 15791: Key Specifications & Formulas for Materials (Plywood)

1. Material Standards Referenced

• IS 303:1989 – Plywood for general purposes
• IS 710:1976 – Marine plywood specification
• IS 5509:2000 – Fire retardant plywood
• IS 5539:1969 – Preservative treated plywood
• IS 1734 (Part 1):1983 – Test methods for density and moisture content

2. Dimensional Tolerances (Clause 7.3)

3. Formaldehyde Emission Measurement (Annex B)

• Desiccator Method: Sample plywood emits formaldehyde absorbed in 100 ml distilled water over 3 days.
• Calculation formula:

[ \text{Formaldehyde (mg)} = x \times 0.15 ]

Where ( x ) = volume (ml) of 0.01 mol/l sodium thiosulphate used in titration.

4. Workmanship and Finish

• As per IS 303 requirements for surface finish and quality.

flowchart TD
    A[Plywood Sample] --> B[Placed in Desiccator]
    B --> C[Distilled Water Absorbs Formaldehyde]
    C --> D[Titration with Sodium Thiosulphate]
    D --> E[Calculate Formaldehyde Emission]

Summary: IS 15791 mandates adherence to referenced IS standards for plywood materials, dimensional tolerances, and formaldehyde emission testing via the desiccator method for quality and safety assurance.

Key Specifications & Formulas for Manufacture (IS 15791)

1. Dimensional Tolerances (Clause 7.3)

2. Formaldehyde Emission Measurement (Annex B, Clause 9.4)

• Desiccator method: Plywood sample kept in airtight desiccator with 100 ml distilled water for 3 days.

• Formaldehyde absorbed in water is titrated with sodium thiosulphate.

• Formula:

  [ \text{Formaldehyde (mg)} = x \times 0.15 ]

  where (x) = volume (ml) of 0.01 mol/l sodium thiosulphate used in titration.

3. Workmanship and Finish

• As per IS 303 (Plywood for general purposes).

Summary Diagram: Manufacture Quality Control Flow

flowchart TD
    A[Raw Material Inspection] --> B[Dimension Checking]
    B --> C[Thickness, Length, Width Tolerances]
    C --> D[Formaldehyde Emission Test]
    D --> E[Workmanship & Finish Check (IS 303)]
    E --> F[Final Product Certification]

Note: For detailed testing procedures and certification, refer to BIS guidelines and IS 303.

IS 15791: Preservative & Fire Retardant Treatment for Plywood

1. Preservative Treatment (Clause 6.1)

• Treatment as per IS 5539.
• Method: Vacuum and pressure impregnation ensuring adequate penetration.
• Preservative loading: 6 to 8 kg/m³ of plywood.

2. Fire Retardant Treatment (Clause 6.2 & 9.3)

• Treatment as per IS 5509.
• Plywood must comply with fire retardant specifications of IS 5509:2000.
• Fire retardant chemicals are impregnated to enhance fire resistance.

3. Referenced Standards

4. Formaldehyde Emission (Annex B)

• Measured by Desiccator Method.
• Formaldehyde absorbed in distilled water reacts with chromotropic acid-sulfuric acid forming a purple chromogen.
• Absorbance measured spectrophotometrically and concentration determined from calibration curve.

Summary Table: Preservative Loading and Fire Retardant Compliance

flowchart LR
    A[Plywood Boards] --> B[Preservative Treatment]
    B -->|Vacuum & Pressure| C[Preservative Loading 6-8 kg/m³]
    A --> D[Fire Retardant Treatment]
    D -->|Chemical Impregnation| E[Compliance with IS 5509]
    E --> F[Fire Resistance Improved]

Note: For detailed chemical formulations and test methods, refer to IS 5509 and IS 5539 documents.

IS 15791: Dimensions and Tolerances for Plywood Boards

1. Standard Thicknesses (Clause 7.2)

Thickness measured to 1 decimal place.

2. Permissible Tolerances on Nominal Sizes (Clause 7.3)

3. Notes

• Squareness and edge straightness tolerances ensure board edges are sufficiently perpendicular and straight.
• Thickness tolerance is relative (%) to nominal thickness.
• Length and width tolerances are absolute values.
• Final values for tests must be rounded per IS 2:1960.

flowchart LR
    A[Nominal Size] --> B[Apply Tolerance]
    B --> C{Dimension}
    C -->|Length| D[+6 mm / -0 mm]
    C -->|Width| E[+3 mm / -0 mm]
    C -->|Thickness <6mm| F[±10%]
    C -->|Thickness ≥6mm| G[±5%]
    C -->|Squareness| H[0.2% or 2 mm/1000 mm]
    C -->|Edge Straightness| I[0.2% or 2 mm/1000 mm]

This summary covers key dimensional specifications and tolerances for plywood as per IS 15791.

IS 15791: Workmanship and Finish - Key Specifications

1. Tolerances on Finished Boards (Clause 7.3)

2. Workmanship and Finish (Clause 8)

• Shall comply with IS 303 (Plywood for general purposes).
• Veneer thickness, joints, grain direction, and permissible defects per IS 303 Clause 7.2.
• Fire retardant treatment as per IS 5509 (Clause 6.2).

3. Additional Notes

• Boards must be free from visible defects affecting performance.
• Edges should be straight and square within specified tolerances.
• Surface finish should be smooth, uniform, and free from delamination.

flowchart TD
    A[Raw Veneers] --> B[Cut & Joint as per IS 303]
    B --> C[Assembly & Bonding]
    C --> D[Finishing & Sanding]
    D --> E[Thickness & Dimension Check]
    E --> F{Within Tolerances?}
    F -- Yes --> G[Final Inspection]
    F -- No --> H[Rework or Reject]

Summary: Ensure dimensional tolerances per Table 7.3, follow IS 303 for workmanship, and apply fire retardant treatment as per IS 5509 for compliance.

IS 15791: Performance Requirements - Key Points

The standard focuses on plywood and related products, emphasizing formaldehyde emission limits and test methods.

1. Formaldehyde Emission Measurement (Annex B)

• Method: Desiccator method (Clause 9.4)

• Procedure:

  • Sample in closed desiccator with 100 ml distilled water for 3 days.
  • Formaldehyde absorbed in water is reacted with iodine and sodium hydroxide.
  • Excess iodine is back-titrated with sodium thiosulphate.

• Calculation:

  [ \text{Formaldehyde (mg)} = x \times 0.15 ]

  where (x) = volume (ml) of 0.01 mol/l sodium thiosulphate used.

2. Rounding Off Results

• Follow IS 2:1960 for rounding numerical values.
• Retain significant places equal to those in the specified values.

3. References for Testing & Specifications

Summary Diagram: Formaldehyde Emission Test

flowchart TD
    A[Sample in Desiccator] --> B[100 ml Distilled Water]
    B --> C[3 days Airtight]
    C --> D[Add Iodine + NaOH]
    D --> E[Keep in Dark 15 min]
    E --> F[Add Sulphuric Acid]
    F --> G[Back-titrate with Sodium Thiosulphate]
    G --> H[Calculate Formaldehyde Emission]

For detailed performance criteria, refer to the specific IS standards listed and the formaldehyde emission limits in IS 15791 Annex B.

IS 15791: Sampling and Testing - Key Specifications and Formulas

Formaldehyde Emission by Desiccator Method (Clause 2.2 & Annex B)

• Sample Preparation: Place plywood sample in closed desiccator with 100 ml distilled water.
• Exposure Time: 3 days airtight for formaldehyde absorption.
• Chemical Treatment:
  • Add 20 ml of 0.01 mol/l iodine solution + 2 ml sodium hydroxide.
  • Keep in dark for 15 min.
  • Add 4 ml 1:1 sulphuric acid.
• Back Titration:
  • Titrate excess iodine with 0.1 mol/l sodium thiosulphate using starch indicator.
• Calculation:

[ \text{Formaldehyde (mg)} = x \times 0.15 ]

Where x = volume (ml) of sodium thiosulphate used.

Rounding Off (IS 2:1960)

• Round test results to the same decimal places as specified values in IS 15791.

Additional References for Sampling & Testing

• IS 1734 (Part 1): Density & Moisture content test methods.
• IS 707: Timber technology glossary.
• IS 303, IS 710: Plywood specifications.

flowchart TD
    A[Plywood Sample] --> B[Closed Desiccator]
    B --> C[100 ml Distilled Water]
    C --> D[3 Days Airtight]
    D --> E[Add Iodine + NaOH]
    E --> F[Dark, 15 min]
    F --> G[Add Sulphuric Acid]
    G --> H[Back Titrate with Na2S2O3]
    H --> I[Calculate Formaldehyde = x * 0.15 mg]

This method quantifies formaldehyde emission critical for plywood quality control.

IS 15791: Marking and Certification Key Points

1. Marking Requirements (Clause 11.1)

Each plywood product must be legibly and indelibly marked with:

• Manufacturer's name or trademark
• Year of manufacture
• Thickness of plywood
• Type of fire retardant treatment (if any)

2. BIS Certification Mark (Clause 11.2 & 11.2.1)

• Use of the Standard Mark is governed by the Bureau of Indian Standards Act, 1986.
• Licence conditions for using the Standard Mark are provided by BIS.
• Manufacturers must comply with BIS rules to use the mark on products.

3. Rounding Off (Clause None)

• Results of tests/analysis should be rounded off as per IS 2:1960 rules.
• Maintain the same number of significant digits as specified in the standard.

Related Standards for Reference:

Summary Diagram: Marking Flow

flowchart LR
    A[Plywood Product] --> B{Marking Required?}
    B -- Yes --> C[Mark Manufacturer Name/Trademark]
    C --> D[Mark Year of Manufacture]
    D --> E[Mark Thickness]
    E --> F[Mark Fire Retardant Type]
    F --> G[Apply BIS Standard Mark (if licensed)]

This ensures traceability, quality assurance, and compliance with BIS regulations for plywood products.

IS 15791 - List of Referenced Indian Standards

Key Specification: Formaldehyde Emission by Desiccator Method (Annex B)

• Sample: Plywood in closed desiccator with 100 ml distilled water.
• Duration: 3 days airtight.
• Analysis:
  • Add 20 ml 0.01 mol/l iodine + 2 ml NaOH.
  • Keep in dark for 15 min.
  • Add 4 ml 1:1 H2SO4.
  • Back titrate excess iodine with 0.1 mol/l sodium thiosulphate using starch indicator.

Formaldehyde Calculation:

[ \text{Formaldehyde (mg)} = x \times 0.15 ]

where x = ml of 0.01 mol/l sodium thiosulphate used.

Notes:

• IS 707 provides definitions for timber terms.
• BIS certification and marking governed by BIS Act, 1986.
• For detailed procedures and specifications, refer to the respective IS documents.

flowchart LR
  A[Plywood Sample] --> B[Closed Desiccator with 100 ml Distilled Water]
  B --> C[3 Days Airtight]
  C --> D[Extract Water for Test]
  D --> E[Add Iodine + NaOH]
  E --> F[Dark for 15 min]
  F --> G[Add Sulphuric Acid]
  G --> H[Back Titrate with Sodium Thiosulphate]
  H --> I[Calculate Formaldehyde Emission]

IS 15791 — Formaldehyde Emission Measurement by Desiccator Method

Key Steps & Setup (Clause 2.1)

• Use a clean desiccator, grease lightly for airtightness.
• Place 8 plywood samples around an inverted 200 ml beaker in a petridish.
• Over the beaker, place a petridish with 1N neutral sodium sulphite solution + thymolphalein indicator.
• Cover the entire setup with a bigger beaker (inverted) and close the desiccator.
• Keep for 3 days at room temperature.

Measurement & Calculation

• Weigh sodium sulphite solution before and after 3 days.
• The mass difference = formaldehyde absorbed.
• Titrate with 1N HCl using thymolphalein indicator.
• Note volume of acid used (V ml).

Calculation formula:

[ \text{Formaldehyde emitted (mg)} = \frac{(V \times N \times 30)}{\text{Sample weight (g)}} ]

Where:

• (V) = volume of HCl used (ml)
• (N) = normality of HCl (1N)
• 30 = molar mass of formaldehyde (g/mol)

Alternative Method (Clause 2.2)

• Place sample in desiccator with 100 ml distilled water.
• After 3 days, add 20 ml 0.01 mol/l iodine + 2 ml NaOH, keep in dark 15 min.
• Add 4 ml 1:1 H2SO4, brown color develops.
• Back titrate with 0.1 mol/l sodium thiosulphate + starch indicator.
• Calculate formaldehyde:

[ \text{Formaldehyde (mg)} = x \times 0.15 ]

Where (x) = ml of sodium thiosulphate used.

Limits (Clause 9.4)

• Formaldehyde emission shall not exceed 0.5 mg/100 g of plywood.

Diagram: Desiccator Setup (Fig. 1)

graph TD
  A[Desiccator Lid] --> B[Inverted Big Beaker]
  B --> C[Petridish with Na2SO3 + Indicator]