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Thursday, March 25, 2010

Things and Myth's About Granite

A few things to know about common myths and misconceptions about granite countertops. Some of these myths are spread by people trying to sell granite, and some by people trying to sell competing products and trying to put down things about granite.

The following are some of the most common myths about granite:

“Granite is heat resistant, so it is perfectly okay to place hot pots on a granite countertop.” While this is true that granite is pretty much resistant to hot temperatures you would have in the kitchen, excessive heat can damage or discolor some types of granite sealers. Constant heating can also generate internal stresses that could cause a crack at a weak spot, such as a natural flaw or calcium in the stone. An easy way to eliminate problems is by using a trivet with feet.

“Granite countertops should be resealed once or twice a year.”
This is a generalization. Many different types of stone sold commercially as “granite.” Some are inherently resistant to staining without applying any sealer, and applying sealers to these stones can actually cause other problems i.e high-quality black stones usually do not need sealers. On the other hand, some stones sold as “granite” are so porous that their shortcomings can’t be solved by even the best sealers. There is no single recommendation that can be made about use of sealers on granite. The answer is specific to each individual type of stone.

“Granite countertops won’t chip, crack or stain.”
High-quality types of granite are very resistant to such damage, but any stone will chip if a hard, heavy object hits a square outside corner. Cracking may result from natural flaws in the stone or errors in fabrication or installation. Some stones sold as “granite” will absorb cooking oils, which darkens those areas significantly. These stains can be very difficult to remove as the only way to do so is by using a poultice. Other stones containing calcium can be etched and whitened by acidic liquids such as citrus juices or vinegar, and these stones are sometimes marketed as “granite,” although true granites are not subject to acid etching. Some sealers themselves can also be damaged by exposure to acidic liquids.

“Granite is second only to diamonds in hardness, so nothing but a diamond can scratch granite.” Granite is very scratch resistant, but it’s not scratch proof. There are many substances harder than granite. Mineral hardness is rated by the Mohs scale, with soft minerals like talc rated as 1 and diamond rated at 10. Due to their high quartz content, most commercial granites are rated about 7 on the Mohs scale. Abrasive substances sometimes found in cleaning products can cause dull spots or tiny scratches on granite if misused. Some stones sold as granite are significantly softer than true granites and are therefore more prone to scratching. Natural stone should be cleaned only with pH neutral, non-abrasive stone cleaning products.

“Granite countertops emit cancer-causing radon and therefore are dangerous” and “Granite countertops are not radioactive, and therefore are perfectly safe.” Both statements are exaggerated. Much of the information found online about radon and granite is not neutral, and has been put out by companies that profit either from selling granite or from selling products that compete with granite.
Radon exposure is a genuine public health problem, as it is considered the second most common cause of lung cancer after smoking cigarettes.
Here is what the EPA says about radon and granite countertops: “Some types of granite may emit gamma radiation above typical background levels. However, at this time, EPA believes that the existing data is insufficient to conclude that the types of granite commonly used in countertops are significantly increasing indoor radon levels. While radiation levels are not typically high, measurement of specific samples may reveal higher than expected levels on a case-by-case basis.”

There are many other potential sources of radon gas within the home. By far the most significant source of radon is the soil beneath the home itself. Foundations and basements can be properly ventilated to disperse excessive levels of radon gas, and this would be preferable in most cases to removing granite countertops. No one should be concerned unless radon testing identifies a problem in a specific home. Despite the relatively low risk from granite, it’s our opinion that the granite industry should screen for high radon emitting stones, and eliminate them from the marketplace.

“Absolute Black granite is the best countertop money can buy.”
Better quality stones sold as Absolute Black granite are outstanding performers. But caution is in order. Stones sold as Absolute Black are quarried in many countries. Originally, the label was applied to a very high quality diabase quarried in Sweden, and later to stones from South Africa. Now stones from many other countries are sold as Absolute Black, including Zimbabwe, Angola, Canada, India and China. Many of the Indian and Chinese stones are of excellent quality, but some unscrupulous companies sell lower-quality stones that may be dyed from grey to black, have excessive flaws, or not be able to be polished to a consistently glossy finish. Knowing that a stone is marketed under the trade name Absolute Black granite is not enough to make an informed decision.

Testing the Granite before you buy.

It would be nice if everyone who sold granite was ethical, truthful and fully informed about types of stone they sell. Unfortunately, thousands of different types of stones are on the market today, and obtaining reliable information about each is difficult.
There is a simple test procedure that can give an accurate picture of a stone’s performance as a countertop. Take a sample of the stone home and before applying any sealer, put teaspoon of water on the stone and observe for darkening and absorption. If the stone starts to darken immediately, it’s very porous, and not a good candidate for a kitchen countertop. If it takes several minutes to darken, the stone will be an adequate performer if properly sealed. If the stone does not darken after 30 minutes, it’s an excellent performer and may not need sealing at all.

Next, take half a lemon, squeeze out some juice and leave the cut lemon and juice on the stone for 30 minutes. Drip vegetable oil onto the stone as well, and let it sit for half an hour. Any signs of acidic etching or oil staining will indicate that this particular stone is not an outstanding performer as a kitchen countertop.

The final test is specially for black granites. Pour a puddle of acetone onto the stone, and wipe the surface thoroughly with a clean rag. If the rag shows black or grey coloration, then the stone has been doctored with an applied dye or wax, and should not be used for a kitchen countertop.

Good luck

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