Stone Maintenance Guide
Marble - Limestone - Granite - Slate
This
report 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.
