Granite Material Problems, Page 2

So many issues with granite can be found easily online at stone sites, kitchen
and bath sites, or just Googling keywords.

Stone shops used to be just that, only stone, but now many shops, mine
included, are doing granite as well as most other materials.  What better way to
learn the strengths and weaknesses of products than to work with them?  The
old stone shops, as well as the stone only shops, tend to gloss over problems.  
One stone fabricator went so far as to say on an open kitchen forum that
consumers were too ignorant or unsophisticated to understand the scientific
studies that I used to support my advice on countertop materials.

Many of the issues are kept hidden by stone fabricators and stone associations
so as not to hurt sales, but behind the scenes, they are working on solutions to
the issues.  The criticism of stones weaknesses have made the producers work
on improving the product, better sealers, resining, rodding, top polishing, repair
processes and under mount sinks are some of the improvements brought about
by competition.  That said, some of the improvements bring other problems to

Sealers cause controversy, even among stone fabricators.  Some say that if
you recommend sealing, you make stone look bad.  Others say if you don't
seal, you have staining.  Sealing products are controversial themselves.  Some
will slow down water stains, others only oil stains, and a few slow down both.  
Some can cause
spalling of the surface, due to blocking the stones ability to
breath, or expel moisture.  Also, notice that some sealers can yellow as it ages,
due to not being UV resistant.

So since a sealer can not completely block out water, thus moisture will be
available, which is all bacteria need to thrive.  Even deep underground, with no
sunlight or nutrients, bacteria thrive.  One type of bacteria turns minerals into
food, while another type uses the waste products left over and so on.

However, in a counter top, there is food available, grease, crumbs, all manner
of proteins, sugars,  and carbohydrates smeared around and ground down into
a paste by use and cleaning, then forced into crevices and pores.

Do a google search on shopping carts and bacteria, see how long they last with
only moisture from hands and nutrients from skin oils.  Countertops are a haven
for bacteria, which is why sanitation is so important.

Denying scientific proof that granite is unsanitary is just trying to justify a
purchase or trying to sell more stone tops.

This is a sore point with stone shops, the bacterial aspects of granite.  Studies
have proven the susceptibility of granite to bacterial colonization and other
studies have show the rapid increase in food borne illness, yet no one has done
a study to find any correlation between the two.  That will be done in the near
future, first a paper study to bring together what has been done already, then
food borne illness records will be checked to see what percentage has granite
countertops in the home.

Here is a short version of what NASA found and why a homeowner would want
to know:

 NASA's findings of over 100,000 bacteria per gram of granite, plus
many, many bacteria spore.  Here is the math, stone averages about 16 pounds
per square foot (3 cm) x 453.6 grams per pound = 7257.6 grams per square

7257.6 x 100,000 bacteria per gram (NASA's figure)= 725,760,000 bacteria per
square foot of countertop.  Average top is around 75 square foot, so
725,760,000 bacteria per square foot x 75 average square foot top =
54,432,000,000 bacteria per countertop.

Over 54 Billion bacteria, just in the cracks and crevices alone, not counting what
is on the surface.  If a 5 log reduction could be done reliably, there would still be
over a half million bacteria left in the cracks and crevices after disinfection.
Twenty minutes after disinfection, the bacteria would have doubled to one
million, forty minutes, two million, an hour later four million, and so on.  In about
four hours, the bacteria have multiplied to 2,229,534,720.  In seven hours, the
bacteria will have multiplied to 150 billion bacteria.

Keep in mind that these NASA figures were for rock taken from a desert
environment, with little food and water available for the bacteria.  Imagine the
average stone top, soaking in moisture from cleaning the top surface, and
humidity from the bottom and edges.

The Marble Institute is a great resource, they have some very good info, with
three exceptions which are the discredited Snyder studies of 1999 and 2006,
and their stance on Radon and radiation in granite.

Some stone shops will say that the Marble Institute's cleaning warnings are
directed toward calcareous stones, ie., marble/limestone, read this warning
copied directly from their website

"Caution: The reader is cautioned that although vinegar was used as a
disinfectant for the purpose of this test, there are some granite species that
contain trace mineral groups which could be attacked by exposure to acidic
solutions. Some sealers, impregnators, or other agents applied to the stone
may also be subject to attack or discoloration from mild acids. Do not use
vinegar as a cleaning agent without consulting your stone supplier as to the
mineralogy of your particular granite as well as the compatibility of any sealer or
impregnator that may have been applied to the stone. Vinegar should never be
used on calcareous stones such as marble, limestone, or travertine."

It seems you must be an expert on cleaning products as well as knowing the
exact composition of your stone and sealer to be able to clean it properly.  How
many granite owners are privy to this?  Most just move into the home after the
top was installed and don't have a clue what type of stone, whether or not that
particular block in that particular quarry had calcite or not, nor do they know
what type or brand of sealer was used.

While on that subject, read the
question about Absolute Blacks chemical
composition on page two.  You will see that knowing the exact composition of
your granite is almost impossible unless that particular block was tested.  (
 It appears the MIA has deleted this information from their website in
reaction to us linking to it.   How strange, usually when one publishes
info online, you try like mad to get people to read it, not prevent them
from reading it.)

See what the fuss is all  about?  Still wonder why so many stone shops don't
want to read this stuff online, or rather they would prefer that their customers
don't read this stuff online.
For the latest information on these issues, including the latest
science being done, please visit our forum at