STONE SEALING
• Should natural stone be sealed?
In some cases it makes perfect sense to seal the stone. Once properly sealed, the stone will be
protected against everyday dirt and spills. In other cases, it is best to leave the stone untreated.
Topical sealers can alter the surface texture and finish, as well as build up on the surface
creating a layer that is less durable than the stone.
• Marble Institute of America Statement of Position On Sealing Natural Stone Countertops
Most granite countertops do not need to be sealed. Before 1995 there were very few quality
penetrating sealers on the market and there were very few cases of staining. Both prior to and
after the availability of penetrating sealers, no cases of food poisoning, radon, or food
preparation issues associated with treated or untreated granites have been reported. If a
homeowner cleans their countertops after each meal, they will rarely, if ever, have staining or
cleanability issues with granite. All this being said, many granite countertops receive additional
benefit from being sealed. That benefit is the further reduction of moisture migration into an
already moisture resistant surface.
Should natural stone counters be sealed? In many cases it makes sense to seal marble and
granite countertops with a quality sealer. The product should have a life expectancy of ten to
fifteen years and be of an oliophobic (resistant to water and oil based stains) nature. Once
properly sealed, the stone will be more resistant against everyday dirt and spills.
In today’s natural stone industry, many species of granite receive a resin treatment at the factory
where the blocks of granite are cut into slabs and then polished. The treatment is used to fill
microfissures, indentations and other minor characteristics that are found in many natural
stones. The reason for the resin treatment is to address what most consumers consider as
imperfections, but in reality are “birth marks”. The consuming public gravitates to perfection,
defined as no “birth marks,” and so the marble and granite industry tries to fulfill the desire. Both
resined as well as unresined slabs will outlast most of our lifetimes. Granite should, and in most
cases will, be the last countertop surface a person will buy, providing a strong return on
investment. The bottom line: Sealing resin treated countertops may increase the resistance of
the already resistant nature of stone (adopted 11/8/06).
Dimension Stone Design Manual, Version VII, page 3-5, 3-6
Factors to consider prior to determining if the stone should be protected:
• What is the hardness, density, and durability of the stone?
• How porous is the stone and how fast will it absorb a liquid (also referred to as the
absorption coefficient)?
• Is the stone expected to be in frequent contact with a staining agent?
• What type of finish was applied to the surface? For example, a polished surface is more
resistant to staining than a honed surface.
• Will the sealant affect the color or other aesthetics of the stone?
• If a resin was applied to the stone, how will the sealant react with the resin?
• Where is the stone located (e.g. countertop, floor, wall, foyer, bathroom, etc)? Residential
or Commercial?
• What type of maintenance program has or will the stone been subjected to?
The type of stone, its finish, its location, and how it is maintained all need to be considered
when determining how to protect the stone. The MIA recommends that these factors be reviewed
with the end-user during the decision making process.
• Should natural stone be sealed?
In some cases it makes perfect sense to seal the stone. Once properly sealed, the stone will be
protected against everyday dirt and spills. In other cases, it is best to leave the stone untreated.
Topical sealers can alter the surface texture and finish, as well as build up on the surface
creating a layer that is less durable than the stone.
• Marble Institute of America Statement of Position On Sealing Natural Stone Countertops
Most granite countertops do not need to be sealed. Before 1995 there were very few quality
penetrating sealers on the market and there were very few cases of staining. Both prior to and
after the availability of penetrating sealers, no cases of food poisoning, radon, or food
preparation issues associated with treated or untreated granites have been reported. If a
homeowner cleans their countertops after each meal, they will rarely, if ever, have staining or
cleanability issues with granite. All this being said, many granite countertops receive additional
benefit from being sealed. That benefit is the further reduction of moisture migration into an
already moisture resistant surface.
Should natural stone counters be sealed? In many cases it makes sense to seal marble and
granite countertops with a quality sealer. The product should have a life expectancy of ten to
fifteen years and be of an oliophobic (resistant to water and oil based stains) nature. Once
properly sealed, the stone will be more resistant against everyday dirt and spills.
In today’s natural stone industry, many species of granite receive a resin treatment at the factory
where the blocks of granite are cut into slabs and then polished. The treatment is used to fill
microfissures, indentations and other minor characteristics that are found in many natural
stones. The reason for the resin treatment is to address what most consumers consider as
imperfections, but in reality are “birth marks”. The consuming public gravitates to perfection,
defined as no “birth marks,” and so the marble and granite industry tries to fulfill the desire. Both
resined as well as unresined slabs will outlast most of our lifetimes. Granite should, and in most
cases will, be the last countertop surface a person will buy, providing a strong return on
investment. The bottom line: Sealing resin treated countertops may increase the resistance of
the already resistant nature of stone (adopted 11/8/06).
Dimension Stone Design Manual, Version VII, page 3-5, 3-6
Factors to consider prior to determining if the stone should be protected:
• What is the hardness, density, and durability of the stone?
• How porous is the stone and how fast will it absorb a liquid (also referred to as the
absorption coefficient)?
• Is the stone expected to be in frequent contact with a staining agent?
• What type of finish was applied to the surface? For example, a polished surface is more
resistant to staining than a honed surface.
• Will the sealant affect the color or other aesthetics of the stone?
• If a resin was applied to the stone, how will the sealant react with the resin?
• Where is the stone located (e.g. countertop, floor, wall, foyer, bathroom, etc)? Residential
or Commercial?
• What type of maintenance program has or will the stone been subjected to?
The type of stone, its finish, its location, and how it is maintained all need to be considered
when determining how to protect the stone. The MIA recommends that these factors be reviewed
with the end-user during the decision making process.
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