MAINTENANCE SKILLS OF FOUR KINDS OF STONE

　　This text is a short summary and general guide of maintenance recommendations and processes which have proved practical for many stone surfaces over the years. It should not be assumed that any particular process description or recommendation is suitable for any particular project or situation without qualification. There are many variables which must be considered when designing a maintenance program including: physical properties of the stone, abrasion risk, hostile factors in the environment, the maintenance budget and the skill of the maintenance personnel. It is highly recommended that a maintenance professional be consulted if there is any doubt about whether or not a specific method or product is safe and effective.
 

　　Marble
　　Composition: Calcite, Calcium Carbonate
　　Hardness: Soft
　　Absorption: Oil, Water
　　Limitations: Absorbs oils and other liquids, easily scratched, acid sensitive
　　Sealer: Penetrating type siloxane or fluoropolymer
　　Cleaner: Natural Soap or Neutral pH detergent
　　Finish: Polished - liquid Paste wax ; others: none

　　Notes: Polished marble is ideal for vertical application but requires a high level of maintenance when used as flooring especially in high traffic situations. Non-reflective finishes perform well as flooring with minimal maintenance once treated with recommended sealers. Kitchen use should be carefully evaluated due to oil absorption.

　　Limestone
　　Composition: Calcite, Calcium Carbonate
　　Hardness : Soft
　　Absorption : Oil, Water
　　Limitations : Absorbs oils and other liquids, easily scratched, acid sensitive, polished-interior use only
　　Sealer : Penetrating type siloxane/fluoropolymer
　　Cleaner: Natural Soap or Neutral pH detergent
　　Finish: Polished - liquid Paste wax ; others: none

　　Notes: Most true limestone types are porous and absorbent. Some limestone is semi-metamorphic and will have physical properties similar to metamorphic marble. If the limestone is metamorphic it is "Marble". For our purposes here, LIMESTONE is the chalky porous type typical of most French and Spanish limestone. Non-reflective finishes are practical as flooring but require sealing to minimize stains. Dense, low absorbent varieties of limestone can be suitable in shower areas but beware of using too soft a limestone in high stress areas. Sealing is normally recommended for both interior and exterior locations.
 

　　Granite
　　Composition: Quartz, Feldspar (varies)
　　Hardness : Hard
　　Absorption : Varies - Oil, Water
　　Limitations : Absorbs oils and other liquids, brittle
　　Sealer : Sub-surface repellents - oil repellent type recommended
　　Cleaner: Neutral pH detergent or pure soap
　　Finish: None Normally - Wax OK

　　Notes: Granite is typical for kitchen counter use. Sealing is recommended for most stones. Granite is the hardest of the polished stones commercially available and is used in high stress situations. Polished granite usually is more absorbent to liquids than many people suppose. Flamed granite surfaces are very absorbent due to the stress fractures in the stone caused by the flaming process and should be sealed if it is desired to maintain the original color and appearance of the stone over time.

　　Slate
　　Composition: Muscovite Chlorite (wide variation in composition)
　　Hardness : Soft - easily scratched
　　Absorption : Low - medium oil, water other liquids
　　Limitations : Absorbs oils/ liquids, cleft planes can spall
　　Sealer : Sub-surface repellents oil repellent type recommended
　　Cleaner: Neutral pH detergent or pure soap
　　Finish: Acrylic OK - wax OK

　　Notes: Cleft slate is very durable in most situations but quality varies. Slate is typically rustic in appearance but some milled or smooth products are available in some varieties. Wear is typically taken on the peaks or high spots of the textured surface. Acrylics are used when a highly reflective finish is desired. Excellent exterior paving stone. Higher absorbency varieties may not be suitable for exterior areas in freezing climates.

　　Slate characteristics vary with source. Domestic is typically black, green or mottled (Pennsylvania) and is relatively dense. Many imported slates are available today with wide ranging physical characteristics and overall suitability. Evaluate your stone for density, tensile strength, absorbency and abrasion resistance. Make sure your slate characteristics are compatible with the intended function.