Code of practice for maintenance and preservation of stones in building

IS 8759: Scope Summary & Key Points

Scope (Clause 0.3):

• Applies to maintenance and preservation of stones in buildings, focusing on sedimentary and porous stones (especially unplastered).
• Covers principal factors causing stone decay and preventive measures.
• Preventive measures are based on Indian practice.
• Includes recommendations on cleaning methods (Clause 3.7): water/steam washing, sand blasting, chemical cleaning.
• References Indian Standards for preservatives (Appendix A), e.g., linseed oil, coal tar, sodium silicate.

Important Specifications:

Preventive Measures Overview:

flowchart TD
    A[Stone Decay Factors] --> B[Physical & Chemical Changes]
    B --> C[Preventive Measures]
    C --> D[Cleaning]
    C --> E[Preservatives Application]
    D --> F[Water/Steam Wash]
    D --> G[Sand Blasting]
    D --> H[Chemical Cleaning]
    E --> I[Linseed Oil]
    E --> J[Coal Tar]
    E --> K[Sodium Silicate]

Note: Use durable stones initially to minimize decay. Follow IS 2-1960 for rounding off test values.

Causes of Deterioration of Stones (IS 8759, Clause 2.0 - 2.9):

• Atmospheric Agencies: Physical and chemical changes due to weathering.
• Rain (2.1): Causes alternate wetting/drying, temperature stresses, and chemical attack from acidic rainwater.
• Sunlight: Leads to thermal expansion and contraction, causing cracks.
• Pollution: Gases like SO2, CO2 react chemically, causing stone decay.
• Frost Action: Water freezing in pores expands, causing disintegration.
• Salt Crystallization: Salts crystallize in pores, exerting pressure and causing flaking.
• Biological Growth: Algae, fungi, and lichens produce acids that degrade stone.
• Iron Fixtures (2.9): Rusting clamps/dowels expand and fracture stone; use anti-corrosive coatings.

Key Preventive Measures:

• Use durable stones with low porosity.
• Apply protective coatings.
• Avoid direct contact with iron fixtures or protect them.
• Control moisture ingress and pollution exposure.

Summary Table: Common Deterioration Mechanisms

flowchart LR
    A[Atmospheric Agencies] --> B[Physical Changes]
    A --> C[Chemical Changes]
    B --> D[Temperature Stresses]
    B --> E[Frost Action]
    C --> F[Acid Rain]
    C --> G[Pollution Gases]
    E --> H[Cracking & Spalling]
    F --> I[Surface Erosion]
    G --> I
    J[Iron Fixtures] --> K[Rust Expansion]
    K --> H

Reference: IS

IS 8759:1977 - Rain Effects on Stone: Key Points & Specifications

1. Rain Effects (Clause 2.1)

• Alternate wetting and drying causes temperature stresses and weathering.
• Rainwater contains gases and acids that chemically disintegrate stone.
• This leads to surface erosion, loss of strength, and aesthetic damage.

2. Protective Measures (Clause 3.3.2)

• Silicone water-repellent treatments:
  • Solutions of silicone in organic solvents or metallic siliconates (e.g., sodium siliconate) in water.
  • On exposure, siliconate decomposes releasing silicone, forming sodium carbonate/sulfate.
  • These treatments reduce water penetration and control staining.

3. Design Considerations

• Account for alternate wetting/drying cycles in durability design.
• Use water-repellent coatings to minimize moisture ingress.
• Provide adequate drainage and overhangs to reduce direct rain impact.

Typical Water Repellency Treatment Application (Conceptual Flow):

flowchart LR
    A[Stone Surface] --> B[Apply Silicone Solution]
    B --> C[Silicone Penetrates Stone]
    C --> D[Formation of Protective Layer]
    D --> E[Reduced Water Absorption & Staining]

No direct formulas or tables are specified in IS 8759 for rain effects, but design must consider:

• Moisture diffusion coefficients
• Thermal expansion stresses due to wetting/drying
• Chemical durability of stone types

For detailed durability design, refer to IS 1121 and IS 1387 for stone properties and weathering resistance.

IS 8759: Temperature Variation in Stones

• Effect: Temperature changes cause alternate heating and cooling, inducing stresses that may crack or disintegrate stones, especially in thicker walls.
• Thin walls: Single stone thin walls experience less temperature variation and thus lower thermal stress.

Key Points (from IS 8759 Clause 2.2)

• Stones subjected to ambient temperature fluctuations develop thermal stresses.
• These stresses can cause cracking and disintegration.
• Thinner stone walls reduce temperature-induced stresses.

Engineering Insight (General Practice)

• Thermal Stress Formula:

[ \sigma_t = E \cdot \alpha \cdot \Delta T ]

Where:

• (\sigma_t) = Thermal stress (Pa)

• (E) = Modulus of elasticity of stone (Pa)

• (\alpha) = Coefficient of linear thermal expansion (per °C)

• (\Delta T) = Temperature variation (°C)

• Typical values for stones:

  • (E) ≈ 5 to 50 GPa (varies by stone type)
  • (\alpha) ≈ 5 to 12 × 10⁻⁶ /°C

Recommendations:

• Use stones with low (\alpha) and high tensile strength for climates with large (\Delta T).
• Provide expansion joints or use thinner stone sections where possible.
• Surface treatments or protective coatings can reduce temperature fluctuations.

flowchart LR
    A[Temperature Variation] --> B[Heating and Cooling Cycles]
    B --> C[Thermal Stresses in Stone]
    C --> D[Cracking / Disintegration]
    D --> E[Maintenance & Preservation Measures]

Summary: IS 8759 highlights the importance of considering temperature variation-induced stresses in stone preservation. Use the thermal stress formula to estimate stresses and design accordingly.

IS 8759: Wind Effects on Stones - Key Points

• Wind Impact: Clause 2.3 highlights that strong winds cause:

  • Abrasion due to grit and dust particles.
  • Accelerated weathering by moisture variation, leading to stone disintegration.

• Durability Consideration:

  • Use stones with good physical structure and chemical composition for better resistance.
  • Porous sedimentary stones are more vulnerable to wind-driven erosion.

• Preventive Measures (from code practice):

  • Regular maintenance to remove abrasive grit.
  • Protective coatings or preservatives (refer to Appendix A of IS 8759).
  • Design consideration to minimize direct wind exposure.

No explicit formulas/tables for wind effects are provided in IS 8759.

Engineering Notes (Supplementary):

• Abrasion Rate Estimation (general concept):

  [ \text{Abrasion Rate} \propto V^n \times C ]

  Where:

  • (V) = wind velocity
  • (n) ≈ 2 to 3 (depends on particle size)
  • (C) = concentration of grit/dust

• Wind Pressure (for structural design reference, IS 8759 does not specify):

  [ p = 0.6 \times V^2 \quad \text{(kN/m}^2) ]

  Where (V) is wind speed in m/s (from IS 8753 or IS 875 Part 3).

Summary Table: Wind Effects on Stone

flowchart LR
    Wind[Strong Wind] -->|Carries grit/dust| Abrasion[Abrasion on Stone]
    Wind -->|Causes moisture variation| Weathering[Accelerated Weathering]
    Abrasion --> Disintegration[Stone Disintegration]
    Weathering --> Disintegration
    Disintegration -->|Leads to| Maintenance[Need for Maintenance & Preservation]

**In brief

Frost Damage - IS 8759 Key Points & Specifications

Clause 2.4 Summary:

• Frost damage occurs when moisture in stone pores freezes.
• Freezing water expands (~9% volume increase), causing internal stresses.
• This leads to cracking, spalling, and disruption of stone.

Key Considerations for Frost Damage:

• Porosity & Absorption: Stones with high porosity absorb more moisture → higher frost damage risk.
• Freezing Expansion: Water expands by about 9% upon freezing.
• Preventive Measures:
  • Use dense, low-porosity stones in cold climates.
  • Ensure good drainage to avoid moisture accumulation.
  • Apply water repellents or sealants to reduce moisture ingress.
  • Avoid iron fixtures that may rust and exacerbate damage (Clause 2.9).

Typical Formula for Frost Pressure:

[ P_f = K \times E \times \alpha \times \Delta T ]

Where:

• (P_f) = Frost pressure causing damage
• (K) = Porosity factor (depends on stone)
• (E) = Modulus of elasticity of stone
• (\alpha) = Coefficient of volumetric expansion of water (~9%)
• (\Delta T) = Temperature drop below freezing

Recommended Stone Properties to Resist Frost:

Summary Diagram:

flowchart LR
    Moisture_in_Pores --> Freezing_Temperature
    Freezing_Temperature --> Water_Expansion[Water Expands ~9%]
    Water_Expansion --> Internal_Stress[Internal Stress in Stone]
    Internal_Stress --> Stone_Damage[Cracking & Spalling]
    Stone_Damage --> Maintenance[Preventive Measures]

In brief: Use dense, low-porosity stones, ensure good drainage, apply protective coatings, and avoid rust-prone fixtures to minimize frost damage as per IS 8759.

IS 8759: Atmospheric Impurities and Stone Deterioration

Key Points from IS 8759:

• Atmospheric Impurities (Clause 2.5):

  • Industrial towns have polluted atmospheres with smoke and acid gases.
  • Stones rich in carbonate of lime (limestones, calcareous sandstones) are highly susceptible to deterioration in such environments.

• Cleaning of Stones (Clause 3.7):

  • Essential for maintenance to restore appearance and remove harmful deposits.
  • Methods include:
    • Washing with water or steam
    • Sand blasting
    • Use of suitable chemicals

• Preservatives (Appendix A):

  • IS standards exist for various preservatives like:
    • Linseed oil (IS 212-1961)
    • Crude coal tar (IS 381-1972)
    • Industrial bitumen (IS 1083-1975)
    • Paraffin wax (IS 6015-1970)
  • These can be used for stone preservation against atmospheric damage.

Summary Table: Effect of Atmospheric Impurities on Stone Types

Practical Notes:

• Chemical deterioration: Acid gases react with carbonate in stones → surface erosion and loss of strength.
• Physical deterioration: Deposition of dust and soot → clogging pores, moisture retention → promotes decay.
• Preservation: Use protective coatings as per IS standards to reduce permeability and chemical attack.

flowchart LR
    A[Atmospheric Impurities] --> B[Acid Gases & Smoke]
    B --> C[Chemical Attack on Carbonate Stones]
    B --> D[Physical Deposition on Stone Surface]
    C --> E[Surface Erosion & Weakening]
    D --> F[Moisture Retention & Decay]
    E & F --> G[Stone Deterioration]
    G --> H[

IS 8759: Chemical Movement Between Stones – Key Points

1. Chemical Interaction (Clause 2.6)

• When limestone and sandstone are placed adjacent, chemicals formed by atmospheric reactions with limestone (mainly calcium carbonate reacting with CO₂ and moisture) penetrate sandstone, causing its disintegration.
• This is a critical durability concern in masonry.

2. Preservatives Acting Chemically (Clause 3.3)

• Common preservatives include:
  • Barium hydroxide
  • Magnesium fluosilicate
• These chemicals react with the stone to enhance durability and reduce chemical degradation.

3. Cleaning Methods (Clause 3.7)

• Cleaning is essential to remove deposits that accelerate deterioration.
• Methods:
  • Washing with water or steam
  • Sand blasting
  • Use of suitable chemicals

4. Binding Materials (Clause 2.7)

• Some binders may chemically attack stones; selection must consider compatibility.

5. Relevant IS Standards on Preservatives (Appendix A)

Summary Diagram: Chemical Movement Effect

flowchart LR
    Limestone -->|Atmospheric gases + moisture| Chemical_Formation
    Chemical_Formation -->|Penetrates| Sandstone
    Sandstone -->|Disintegration| Deterioration
    Preservatives -->|Protect| Stone

Use caution when placing limestone next to sandstone; apply preservatives and cleaning regimes per IS 8759 to mitigate chemical damage.

IS 8759: Effects of Binding Materials on Stones - Key Points

1. Nature of Binding Materials (Clause 2.7)

• Certain binding materials can adversely affect stones by chemical reaction or physical incompatibility.
• Selection must ensure compatibility to avoid deterioration.

2. Cleaning of Stones (Clause 3.7)

• Essential for maintenance to restore appearance and remove harmful deposits.
• Methods include:
  • Washing with water or steam
  • Sandblasting
  • Use of suitable chemicals (avoid aggressive agents that damage stone)

3. Preservation Measures (Clause 3.0)

• Prevent decay by:
  • Filling stone pores with preservatives
  • Providing a protective coating to block moisture ingress
  • Reacting chemically to form a hard, durable surface

4. Recommended Preservatives (Appendix A)

Summary Table: Effects & Prevention

flowchart LR
    A[Binding Material] --> B{Effect on Stone?}
    B -->|Adverse| C[Select Compatible Material]
    B -->|Neutral| D[Proceed]
    C --> E[Use Preservatives]
    E --> F[Fill Pores]
    E --> G[Apply Coating]
    E --> H[Form

IS 8759:1977 - Vegetation Growth on Stone Structures

Key Points from Clause 2.8:

• Certain trees and creepers penetrate stone joints with roots seeking food and stability.
• This root penetration causes physical damage and accelerates stone decay.

Preventive Measures (General Guidance):

• Regular inspection to detect early root growth.
• Removal of vegetation carefully without damaging stone.
• Use of chemical preservatives to inhibit root growth (refer to Appendix A of IS 8759 for recommended preservatives).
• Ensure tight joints and proper pointing to prevent root ingress.

Important Specifications:

Summary Formula (Conceptual):

• Damage ∝ Root Penetration Force × Time
• Minimize Damage by reducing root ingress and exposure time.

flowchart LR
    Vegetation_Growth --> Root_Penetration
    Root_Penetration --> Stone_Joint_Damage
    Stone_Joint_Damage --> Accelerated_Deterioration
    Preventive_Measures --> Vegetation_Removal
    Preventive_Measures --> Chemical_Treatment
    Preventive_Measures --> Joint_Repair
    Vegetation_Growth -.-> Preventive_Measures

Note: IS 8759 focuses on maintenance; detailed mechanical or chemical formulas for root force are not provided but can be supplemented by general structural preservation practices.

Damage Due to Iron Fixtures (IS 8759 - Clause 2.9)

• Issue: Iron or steel clamps and dowels embedded in stone can rust.
• Effect: Rust causes expansion, leading to fracturing and damage of stone.
• Prevention:
  • Apply anti-corrosive paint or suitable coatings on iron fixtures.
  • Use non-corrosive materials or stainless steel where possible.
  • Ensure proper maintenance to avoid moisture ingress.

Key Specifications & Recommendations

Additional Notes (from IS Code of Practice for Maintenance of Stones)

• Use durable stones with good physical and chemical stability.
• Regular maintenance and preservation are crucial to prevent decay.
• Avoid porous stones in damp environments or protect them adequately.

flowchart LR
    A[Iron Fixture] --> B{Rust Formation?}
    B -- Yes --> C[Expansion]
    C --> D[Stone Fracture]
    B -- No --> E[No Damage]
    F[Apply Anti-corrosive Coating] --> B
    G[Use Stainless Steel] --> B

Summary: To prevent damage due to iron fixtures in stone structures, always protect iron components with anti-corrosive coatings or use corrosion-resistant materials, and maintain regularly to avoid rust-induced expansion and stone damage.

IS 8759: Maintenance & Preservation of Stones in Buildings

Key Points & Practices

• Cleaning Methods (Clause 3.7):

  • Washing with water or steam to remove surface dirt.
  • Sand blasting for tough deposits.
  • Use of suitable chemicals for stains or biological growth.

• Preservatives (Appendix A):

  • Linseed oil (raw/refined)
  • Crude coal tar
  • Sodium silicate
  • Industrial bitumen
  • White oil (light technical)
  • Paraffin wax
  • Barium hydroxide

General Maintenance Guidelines

• Remove deposits that cause stone deterioration.
• Avoid harsh chemicals that damage stone texture.
• Use preservatives to enhance stone durability and water resistance.

Typical Cleaning & Preservation Workflow

flowchart LR
    A[Inspection] --> B[Cleaning]
    B --> C{Type of Dirt}
    C -->|Surface dirt| D[Water/Steam Wash]
    C -->|Hard deposits| E[Sand Blasting]
    C -->|Stains/Bio growth| F[Chemical Cleaning]
    D & E & F --> G[Drying]
    G --> H[Application of Preservatives]
    H --> I[Regular Monitoring]

Notes

• No specific numerical formulas or tables are provided in IS 8759.
• Follow manufacturer instructions for preservative application rates.
• Regular maintenance intervals depend on environmental exposure.

Summary: IS 8759 emphasizes cleaning by water/steam, sand blasting, and chemicals, followed by preservative application to maintain stone integrity and appearance.

IS 8759 - Surface Coating Preservatives: Key Points

Purpose (Clause 3.0)

• Prevent stone decay by denying moisture and atmospheric agents access.
• Methods:
  • Fill stone pores.
  • Provide moisture barrier coating.
  • Chemically harden stone surface.

Types of Surface Coating Preservatives (Clause 3.1)

• Coal tar, bitumen, paraffin oil, linseed oil (mixed or unmixed with paint)
  • Pros: Protective.
  • Cons: Affect stone appearance; need frequent maintenance.
• Silicate solutions (potash or soda)
  • Hardens stone surface chemically.

Impregnating Preservatives (Clause 3.2)

• Silicone-based products:
  • Water repellent.
  • Penetrate pores.
  • Applied by brushing, dipping, or spraying.
• Others: Polyvinyl acetate, polymethyl methacrylate.

Application Guidelines

• Apply preservatives after sun drying and before sunset.
• Cleaning stones before preservation is essential (Clause 3.7).

Relevant IS Standards (Appendix A)

Summary Table: Preservation Methods

flowchart TD
  A[Stone Surface] --> B[Sun Drying

IS 8759: Non-Chemical Impregnating Preservatives for Stone

Key Points from IS 8759:

• Type: Silicone-based products are primary non-chemical impregnating preservatives.
• Action: They penetrate capillary pores, creating a water-repellent film inside and on the surface without chemical reaction.
• Application: Diluted in toluene or white spirit; applied by brushing, dipping, or spraying.
• Other Materials: Polyvinyl acetate and polymethyl methacrylate also used similarly.
• Effectiveness: Best for indoor, dry conditions (e.g., museum exhibits).

Specifications & Application:

Preservation Mechanism:

• Fills pores → blocks moisture ingress.
• Forms film → repels water on surface and depth.
• No chemical reaction → preserves natural stone appearance.

Summary Diagram:

flowchart LR
    A[Stone Surface] --> B[Capillary Pores]
    B --> C[Silicone-based Preservative]
    C --> D[Water-repellent Film]
    D --> E[Prevents Moisture Penetration]
    E --> F[Protects Stone from Decay]

Additional Notes:

• Surface Coating Preservatives (Clause 3.1): Coal tar, bitumen, linseed oil; may alter appearance.
• Cleaning (Clause 3.7): Essential before preservation; methods include water washing, steam, sand blasting.

Use non-chemical impregnating preservatives where maintaining stone aesthetics and indoor dry conditions are priorities.

IS 8759: Chemical Action Preservatives for Stone

Key Points from IS 8759:

• Chemical Action Preservatives (Clause 3.3):

  • Examples: Barium hydroxide, Magnesium fluosilicate.
  • They chemically react with stone constituents to form a hard, durable surface.

• Purpose of Preservatives (Clause 3.0):

  • Fill pores of stone.
  • Provide a surface coating to prevent moisture ingress.
  • React chemically to enhance surface hardness and durability.

• Application Methods:

  • Brushing, dipping, or spraying.

Specifications & Standards (Appendix A):

Summary Table for Chemical Preservatives:

Typical Chemical Reaction (Conceptual):

Stone constituents + Barium hydroxide → Insoluble compounds → Hard, protective surface

Diagram: Preservation Mechanism

flowchart LR
    A[Atmospheric Agents] -->|Attack| B(Stone Surface)
    C[Preservative Chemical] -->|Fills pores & reacts| B
    B -->|Prevents| D[Moisture ingress & decay]
    D -->|Protects| E[Stone durability]

Note: For detailed mix proportions and application methods, refer to the specific IS codes listed above.

IS 8759: Use of Paints & Surface Coatings on Stones

Key Points from IS 8759:

• Clause 3.4:

  • Painting is a protective measure but not recommended for monumental/historical buildings as it masks natural stone color and texture.

• Clause 3.1 (Surface Coating Preservatives):

  • Apply after sun-drying the stone surface, preferably before sunset.
  • Common preservatives:
    • Coal tar, bitumen, paraffin oil, linseed oil (pure or mixed with paint).
    • Silicate of potash/soda solutions to harden the stone surface.
  • These coatings may alter stone appearance and need regular maintenance.

• Clause 3.7 (Cleaning):

  • Essential for maintenance to remove deposits causing deterioration.
  • Methods: washing with water/steam, sandblasting, or chemical cleaning.

Recommended Preservatives (Appendix A):

Summary of Application:

• Preparation: Dry stone surface thoroughly in sunlight.
• Application time: Before sunset to avoid rapid drying/cracking.
• Maintenance: Regular inspection and reapplication needed due to weathering.

flowchart TD
    A[Stone Surface] --> B[Sun Drying]
    B --> C[Apply Preservative]
    C --> D{Type of Preservative}
    D --> E[Coal Tar/Bitumen/Oils]
    D --> F[Silicate Solution]
    E --> G[Protects but alters appearance]
    F --> H[Hardens surface

IS 8759 on Limewash & Stone Preservation: Key Points

• Limewash (Clause 3.5):

  • Not recommended for old buildings as it spoils their appearance.
  • Though traditionally used, it does not preserve stone effectively.

• Surface Coating Preservatives (Clause 3.1):

  • Applied after sun-drying the stone surface, preferably before sunset.
  • Types include:
    • Coal tar, bitumen, paraffin oil, linseed oil (alone or mixed with paint).
    • Silicate solutions (potash/soda) that harden stone surfaces.
  • Most oils and tars affect stone aesthetics and need frequent maintenance.

• Cleaning of Stones (Clause 3.7):

  • Essential to restore natural look and prevent deterioration.
  • Methods: water/steam washing, sand blasting, or chemical cleaning.

• Relevant IS Standards on Preservatives (Appendix A):

  • Linseed oil: IS 212-1961, IS 381-1972
  • Coal tar: IS 1083-1975
  • Sodium silicate: IS (first revision)
  • Industrial bitumen: IS 1083-1975
  • Paraffin wax: IS 6015-1970

Summary Table: Surface Preservatives & Effects

flowchart LR
    A[Stone Surface] --> B[Sun-drying]
    B --> C[Apply Preservative Before Sunset]
    C --> D{Type of Preservative}
    D -->|Coal tar/Bitumen| E[Masks appearance, needs maintenance]
    D -->|Linseed oil| E
    D -->|Sodium Silicate| F[Hardens surface,

IS 8759: Cleaning of Stones - Key Points

Clause 3.7 Summary:

• Cleaning is vital for maintenance to restore stone’s natural appearance and prevent deterioration.
• Methods include:
  • Washing with water or steam
  • Sand blasting
  • Use of suitable chemicals

Important Specifications:

• Use gentle cleaning to avoid damaging stone surface.
• Chemicals must be compatible with stone type to prevent chemical attack.
• Avoid high-pressure washing on soft or porous stones.

Related Preservatives (Appendix A):

Recommendations:

• Select cleaning method based on stone type and level of soiling.
• Test chemicals on small areas before full application.
• Follow IS 2-1960 for rounding off test values.

flowchart TD
    A[Stone Surface] --> B{Cleaning Method?}
    B -->|Water/Steam| C[Gentle washing]
    B -->|Sand Blasting| D[Use on hard stones only]
    B -->|Chemicals| E[Compatibility check]
    C --> F[Restored appearance]
    D --> F
    E --> F

This ensures effective cleaning while preserving stone integrity.

IS 8759: Code of Practice for Maintenance and Preservation of Stones in Buildings

Key Points on Preservatives (Appendix A, Clause 0.3)

• The code lists relevant Indian Standards for common preservatives used in stone maintenance:

  Preservative	IS Code	Year
  Linseed oil (raw/refined)	IS 212 / 381	1961/72
  Crude coal tar	IS 1083	1975
  Sodium silicate	IS (1st rev.)	-
  Industrial bitumen	IS (revised)	-
  White oil (light technical)	IS 4654	1968
  Paraffin wax	IS 6015	1970
  Barium hydroxide	IS (not specified)	-

Preservation Practices (Clause 3.7)

• Cleaning of stones is essential to remove deposits causing deterioration.
• Methods include:
  • Washing with water or steam
  • Sand blasting
  • Use of suitable chemicals (refer preservatives above)

Additional Notes

• Durability depends on stone's physical and chemical properties.
• Use durable stones initially to minimize decay.
• Preservation is especially critical for porous sedimentary stones.
• Follow IS 2-1960 for rounding off test values.

Summary Diagram of Preservation Process

flowchart TD
    A[Stone Deterioration] --> B[Cleaning]
    B --> C{Method}
    C -->|Water/Steam| D[Wash]
    C -->|Sand Blasting| E[Blast]
    C -->|Chemical| F[Apply Preservatives]
    F --> G[Linseed Oil / Coal Tar / Bitumen etc.]
    G --> H[Restored Stone Durability]

This code provides a framework for selecting preservatives per IS standards and cleaning methods to maintain stone in buildings effectively.