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Facts about Granite Slab Quality Variables

Posted by oldryder (My Page) on
Sun, Dec 9, 12 at 0:03

I am a fabricator with many years experience. I see a lot of mis-information about stone on the website so I wanted to offer some facts:

Note most of the following applies to any natural stone.

0. there are many different kinds of stone which are used in countertops. some are only slightly harder than jello and roughly as adsorbent as a sponge. Others are practically impervious to stains and only slightly softer than diamond. A good fabricator will make certain you understand the material properties of the stone you selected. (Note: Interior designers are notorious for specifying stone based on the "look" with no consideration for the stones material characteristics in the application.)

1. Slab suppliers are NOT all alike. At the quarry (in Brazil, Saudi Arabia, Russia, Denmark, or many, many other places) slabs are graded based on color, lack of fissures, lack of cracks, lack of (or presence of desirable) inclusions.
Some slab suppliers buy only 1 grade material, some buy cheaper.

2. Many stones are treated in the polishing process with a resin which is applied before polishing. This resin process fills the small pits (too small to feel with your fingertips but visible with the right lighting). This is done because the stone is more commercially valuable with the pits eliminated. The resin treatment process also makes the stone much more stain resistant.

3. the resin treatment does change the color of the slab slightly and on light colors this color difference will be evident on the edges. a quality fabricator treats the edge during the finishing process (before final polish) to make the edge color match the top.

4. Dyed stones are becoming more prevalent. The fabricator has to treat the edges during the finishing process so the edge color matches the top.

5. crappy stone is full of fissures and/or fill. fissures can be considered a natural feature of the stone but they do present challenges and limitations for the fabricator.
Fill is epoxy filler applied at the quarry to fill blowouts that occur during poliishing or sawing the slabs from the block. small fills (maybe the size of a quarter) can be tolerated in an otherwise beautiful stone. some slabs have much more fill. often the fabricator can work around fill. A good fabricator will make sure you know there is fill and where it will be in your countertops as it could easily be much more conspicious in your countertop than as part of the slab.

6. Many stones used in countertops are very stain resistant. Others, like the various limestones and marble colors, are very easily stained even when properly sealed. These stone are so porous and hydrophillic that when placed on a wet saw table the top of the stone will start showing wet spots from water wicked up thru the stone after only a few minutes.

7. some stones have material properties which preclude certain edge profiles. Others are so easily chipped that only a moderately rounded edge is advisable. Also, some stones can be rock pitched easily and on others it's almost impossible. If a fabricator calls you and says a particular edge isn't working on your stone it'snot because he doesn't want to do it; it's because the stone won't let him.


Follow-Up Postings:

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RE: Facts about Granite Slab Quality Variables

Thanks, very useful. Would you be willing to be more specific about which stones fall into which category (as you did in point 6)?
Also, what grade of stone is a cutoff point below which you wouldn't recommend? Can I ask the stoneyard the grade of the slab that I am looking at?

I have been considering using a local installer/fabricator whose quotes are much less than others; now I wonder if it is lower quality stone (even though from the same local stoneyard as other suppliers)

Raee


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RE: Facts about Granite Slab Quality Variables

oldryder, thank you for sharing your knowledge. Which granite stones are harder and less porous in general if they are quality?


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RE: Facts about Granite Slab Quality Variables

oldryder, thanks for the helpful information. It's so hard as a consumer to know if you are getting something that will work well for you in your kitchen. Can you speak a little about different kinds of sealers and how effective they are? I am buying a light colored granite with a lot of movement. I know going into it that stains are a possibility, though I have no idea how porous the stone I selected is.

My fabricator offers a "lifetime" sealer treatment for nearly $1,000. To me this seems like being offered the extended warranty on electronics - rarely worth the money for the consumer. What is your experience with different sealers? For a light colored granite, should I seal multiple times when I first get it? Seal yearly? Pay the premium for "lifetime" sealer? Thanks for any advice you can offer.


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RE: Facts about Granite Slab Quality Variables

raee: any stone can be 1st, 2nd, or lower grade. If it looks like what you want and the stone has acceptable material properties (correct thickness and not full of cracks, fill, or fissures) then I wouldn't worry about it.

lynn 2006: granites are assigned "classes". Class 5 granites are the hardest although most actual granites are planty hard enough to be durable.

Soibean; generally there are normal and "porous plus" type sealers. The porous plus type are designed to seal the larger pores in more porous stones. sealers can also be water based or solvent based. In my experience the solvent based sealers are more effective. sealer may also have "enhancer" which helps bring out the color in some stones and particularly in honed stones. We have had only a dozen or so staining incidents in a couple 1000 jobs. I would not pay $1000 premium. More often than not if a stone is stained the stain can be removed with a poultice application using the correct solvent for the stain.

hope this was helpful


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follow up question for old ryderRE: Facts about Granite Slab Qual

Oldryder

we have received our granite (snowflake granite). As a precaution we are thinking of using a sealer right away. the fabricator stated they would seal it of course but it looks to us like it could use another treatment - we noticed that when there is liquid or food on the granite there is a stain which eventually evaporates - but we are surpised to see the stain at all. Anyway, do you see anything wrong with us giving it another seal treatment now? also, what sealer would you recommend that we could purchase ourselves?
thanks in advance


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RE: Facts about Granite Slab Quality Variables

That was a great post Oldryder. The only thing I see to be different in my experience--and it might be a regional difference--is that stoneyards' "grading" of their slabs has to do with rarity and supply, not color\hardness\fissures\cracks etc. So, around here, when you go to a stoneyard and see a slab that has a sign that says "grade 1" or "class 1" (or sometimes they do it by A, B, C), it means it is the most expensive tier because the yard has very little of it, and will only be able to obtain very little of it in the future.

Frequently a slab in one stoneyard is "Grade 1", and that same stone in a stoneyard a mile away is "Grade 3" with the accompanying difference in price. That's because the yard classifying it as "Grade 3" has a good source for that particular stone, or got a big lot if it in, so has many slabs to sell. At least around here, the class or grade the stoneyard gives to a slab has nothing whatsoever to do with its quality or hardness\absorption rate.

This post was edited by akchicago on Sat, Feb 2, 13 at 18:52


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RE: Facts about Granite Slab Quality Variables

oldryder, thank you for the helpful information. What can be done after the fact? My granite is rough and sheds, it's a light stone and the tiny pits you speak of are what is bothering me. It may not have resin on it, I don't have any way to know. It has an ogee edge so I guess it was good enough to do that.

I have spoken with my fabricator who said he would try to hone the island as it is the worst. It's depressing. I did not think I bought lower grade stone but it appears something is not right with it. It has been a year now and it still sheds tiny pepper like dots and those tiny pits feel so rough. I'm tempted to polyurethane it so upsetting it is to me. I would like those little pits to go away. There are no fissures but there are some fill places that are about the size of a pencil eraser. Is there anything that can be done now to the stone? If I hone the island will it help? But then I'll only have a honed island and not the perimeter.

In summary, is there a product to smooth out a stone after the installation?

Will hone-ing help it at all, and is it possible to hone the perimeter on site?

Thanks so much in advance for any advice you might have.


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RE: Facts about Granite Slab Quality Variables

SaraKat: the honing will help but the problem you are having could easily resurface (no pun intended) even on the honed area.

you are right that your stone is almost certainly not resined as the problems you describe are exactly what it was designed to eliminate.

your best best is a resin surface treatment like "HydroShield" which provides a lifetime warranty against staining and actually coats the stone. The stone will be a little glossier when done but your shedding problem should be gone.


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RE: Facts about Granite Slab Quality Variables

Thanks very much oldryder, that's the information I've been needing. I thought this was the problem.

The supplier granite yard is out of business and the fabricator although it was one of their suppliers says there is nothing they can do about it.

The only reason we are looking at replacing is that we have the problem with shedding, the awful feel of this stone that feels dirty and like it is covered with tiny pepper grains no matter how many times I wipe it down. It snags my dish cloth and the sink recently cracked and has to be replaced. The sink is a mystery as to why that happened.

Thank you so very much I will check in to the Hydro Shield and hopefully it will make it more tolerable. The island is the worst thank goodness since we could just replace that to keep down the cost. I really wasn't planning on an expense like this coming up this soon! It hasn't even been a year yet. The granite fabricator gave me a replacement price for new granite of $4500 which is the same as we paid for the original granite and it was supposed to be their super discounted price ....sigh. Live and learn, thank you very much again.


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RE: Facts about Granite Slab Quality Variables

Oldryder

Is there a specific brand/type of solvent sealer your recommend and where could we purchase it from?
any issues on how often you apply the sealer?
thanks


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RE: Facts about Granite Slab Quality Variables

We have used several brands over the past decade but liked only 2. One is "Stone Tech" by Dupont. There are several different Stone Tech products so you need to read the specs to get the right one for your particular stone. Stone Tech "Bulletproof" sealer is the best sealer I've come across but it's expensive and overkill for most granites.

A 2nd alternative is "511" and "511 Porous Plus" (for more porous stones like marble and limestone)by Miracle Sealants.

In general I've found the solvent based sealers to be better than the water based ones.

Both brands are available on-line and most fab shops carry sealer in consumer size containers. Some sealers include an "enhancer" which helps bring out the color in honed stone.

We recommend sealing once per year. Most granites don't even need it that often but it will never hurt to do it too often. Easy to follow instructions are on the containers and it usually takes longer to clear the counters than it does to seal them.

If you have existing stone and don't know what sealer (if any) is on there you can strip it with acetone (which won't hurt the stone) and then reseal.


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RE: Facts about Granite Slab Quality Variables

Oldryder, thank you for starting this thread. I'm sure I'm not alone in feeling like a kid in the candy shop reading here.

If you don't mind, would you comment on minimizing fingerprints, watermarks and upkeep on Absolute Black from Zimbabwe? I recently read honed>satin>flamed>leathered is an order for decreasing fingerprints. I suspect it's rather difficult to find the last three processed AB, especially leathered, and still be in a medium price range. Thank you.


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RE: Facts about Granite Slab Quality Variables

Oldryder

do you have any experience with snowflakes granite Here is a link which shows the image http://www.marble.com/materials/granite/Snowflakes#1654

In particular, I am interested in understanding it's hardness or resistance to stain.

thanks


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RE: Facts about Granite Slab Quality Variables

Sparkling Water: you are correct that an unpolished finish will show less (or none) fingerprints compared to a polished finish. A flamed finish is very coarse used primarily for stair treads or other flooring applications.

HOned and satin are typically quite similar. "leather" typically has a little texture to it. Cold Spring Granite has a very attractive "Pacific" finish which combines a polished and textured look and they ship their stone all over the country so its at least possible your local fabricator could get it.

In many areas you can get a honed or other finish on a polished slab for an upcharge. Watch out here is that removing the polish "washes out" the color so you need to be certain you want the finish as it is a non-refundable special order when done as a treatment to a polished slab. Adding a finish is typically going to cost you $8 - 12 per sq. ft. in my area of the country.

Aarons123: your stone looks like what is called "Bianco Romano" locally. Pretty stuff. I have a vanity of it in my showroom. Some slab suppliers deliberately create their own name for stones to limit the ability of the consumer to compare pricing. Very hard stone. Somewhat chippy for the fabricator which imposes some limitations on suitable edge profiles. Typical resistance to staining (which means quite good)


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RE: Facts about Granite Slab Quality Variables

Hi, Oldryder,

It is not Bianco Romano; the supplier we purchased from sells Bianco Romano as well. I am linking to their picture of the Snowflakes granite. According to our fabricator, they used Stonetech BulletProof to seal it, but we still see water spots. I think we will reseal it ourselves - hopefully a second or third coat will do the trick.

Here is a link that might be useful: Snowflakes Granite


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RE: Facts about Granite Slab Quality Variables

Most of the names are puffery, and say nothing about the actual type of stone.


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RE: Facts about Granite Slab Quality Variables

Thank you olddryer. Good info to know.


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question for Oldryder

Oldryder
A question I have been meaning to ask. I have seen Snowflakes granite at two suppliers. Interestingly, the two suppliers list it as coming from different countries: one from Brazil and the other from India. I was surprised to see that a stone with a distinct look could be found in quarries from two different countries. Does this seem reasonable to you? Is it common?
thanks in advance


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RE: Facts about Granite Slab Quality Variables

aarons123: there are quite a few stones that originate in multiple countries. Some stones are quarried at the point of origin and then shipped as blocks to another country for processing into slabs. This could result in differeent "origins" for the same stone as one supplier might do the slab processing local to the quarry and another could be in a different country.


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RE: Facts about Granite Slab Quality Variables

Do you believe that ALL granite should be sealed, or are there some that don't need sealing? In doing some research online a while ago, I found some warnings about sealing really hard granites (which, according to them, are generally dark) because they are so hard that the sealer will not soak into the stone and becomes a problem. I'm considering Caledonia, which was identified as one of the harder stones, and I don't want to cause more problems by sealing something that shouldn't be sealed. Conversely, I don't wnat to fail to seal the granite and have diffiuclty because of that.


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RE: Facts about Granite Slab Quality Variables

sail-away: in my experience you can't hurt a granite by sealing it. some very dense granites are inherently resistant to staining because the pores in the stone are very small but I would still seal any granite that hasn't been resined. it doesn't cost much so it's essentially cheap insurance to seal it.


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RE: Facts about Granite Slab Quality Variables

I have to disagree with Oldryder regarding sealing "any granite that hasn't been resined". As Sail-away has noted in her research, a non-absorptive granite like Absolute Black, Uba Tuba, or Volga Blue, will not benefit from sealant. Sealant will actually mar those stones' appearance with streaks, hazing, and film until the sealer is removed.

I am going to quote Stonegirl, another member of the Kitchens Forum: "Not all stones need sealer. Stones like Blue Pearl, Ubatuba, Black Galaxy, Verde Peacock, Verde Butterfly, Platinum Pearl and many others are too dense to absorb any liquids - sealers included. Sealers only protect stone from staining through absorption, so in stones with low absorption co-efficients, sealing would be superfluous. Sealing dense stones could lead to nasty results, such as streaking and ghost etching, so DO NOT go by the motto of "seal it anyway, it could not hurt". Rather test your stone for absorption by dripping water on it to see if it darkens any. If the water has no effect on the stone, sealing it is unnecessary."

I would add to Stonegirl's advice that there is a list of granites and their absorption rates in the link below. To put in perspective, Absolute Black has about the lowest rate, at 0.05-.15%. My Piracema granite is quite low at 0.1-.3%, and has never needed sealing. By contrast, a granite that does need to be sealed is Imperial White with an absorption rate of 0.35-.45%. So, if you do not want to have to seal your granite, find one with a low absorption rate, which therefore won't need sealer.

Sail-away - the Caledonia stone you mentioned is on the linked list showing an absorption rate of 0.1-0.2% - pretty darn low! A similar rate to my Piracema, and I have not sealed it in 7 years, and it looks like the day it was installed.

Here is a link that might be useful: List with Granites' Absorption Rates

This post was edited by akchicago on Thu, Feb 7, 13 at 1:28


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RE: Facts about Granite Slab Quality Variables

Thanks, oldryder and akchicago, for your responses. Of course, I remain a bit confused, given the strong stance by people on each side of this issue. We did a trial run with granite in our master bath to see how we like it. We used a black granite and I don't remember for sure what it was called---maybe Blue Pearl---but it was definitely black, not blue. We did not seal it, and it has been doing fine. Of course, the kitchen will get harder use, with more potential for stains, and I want to be sure it will stand up to heavy use.

I really wanted the black granite in the kitchen, but having it in the master bath has shown me that a dark countertop might be too high maintenance. So I'm leaning toward a sample of New Caledonia that I picked up several years ago---but only if I can find a slab with the same mix of grey, black, and tan---some I've seen onlne seem to be mostly or all grey and black, and I need to tie in the tan a bit. Thanks for providing the chart about the absorption rates---I think I've seen it, but I couldn't find it again. I just wish that names were more standardized, so that you could be more sure of what you're getting when you go look at the stone yards.


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RE: Facts about Granite Slab Quality Variables

akchicago - thx for the link. some useful stuff there. I stand by my assertion that it's ok to seal any granite. we've sealed black absolute many times and never had problems like you describe. We did once have some black that had smeary streaks but it was traced to the stone itself which had been dyed inconsistently. we at first thought it was a sealer issue and stripped and resealed it to no effect. finally I thought to look at some of the remnants from the job and was able to prove the smears were in the stone itself as the remnants had never been sealed. we won't buy dyed black anymore for this reason.

in my experience on a stone that is only very slightly porous less sealer is absorbed but it does not result in smearing or streaks unless improperly applied.


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RE: Facts about Granite Slab Quality Variables

Oldryder- I have to agree with Akchicago. We recently had Absolute Black installed in our kitchen and we are dealing with a real problem with etching. We can't leave anything with any kind of acidity on it without a gray ring forming. The ring appears after as little as 15 minutes.

We are trying to resolve the issue with the fabricator, but their solution is to remove existing sealer and re-seal. I think it's the sealer that's etching, and we would be better off without one. They types of liquids that are producing the rings are white grape juice, ice tea with lemon, and of course, red wine. Any ideas on what might be going on?

One last thing, I did try to test for dyed stone with nail polish remover. Nothing came off on the cloth so I'm thinking the stone is good.


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RE: Facts about Granite Slab Quality Variables

jacrm57: the problem you describe is not etching. etching refers to chemical action which actually dissolves the stone. It's normally a problem limited to stones with calcium carbonate like marble and limestone although the acid in household rust remover products can etch many granites.

It does sound like a sealer issue to me. I would strip the tops with acetone and then use a different sealer. It's possible your fabricator got a bad batch of sealer (it happened to use once secveral years ago.)

your problem is unusual as we've done many many Absolute Black tops and never encountered the problem you describe. I did immediately suspect dyed stone. I'll make a few inquiries and if I learn something useful I'll post it here. If you or your fabricator figure it out I'd love to hear the solution.


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question for oldryder

oldryder

I was wondering what your thoughts were on daily granite cleaners such as AGM Granite and Marble cleaner? available at mrstone.com

thanks!


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RE: Facts about Granite Slab Quality Variables

Oldryder- Thanks for explaining the term "etching". We should know soon if the process of removing sealer and re-sealing does the trick. The company is scheduled to come over tomorrow. I'll report the results and what they used.


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Need opinion about granite for island can I find enough big piece

My Hubby is wanting me to take 12 inches off ofour 11 foot island that is at the cabinet shop being built. Because we can only find granite 124 inches not anything longer and really didn't want a seam. I don't have a sink or anything in it?? Got opinions....can they really make a seam look good in granite??


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RE: Facts about Granite Slab Quality Variables

Waterpondgal - I'm not one of the experts, but one way to make a seam look good in granite with veining is with bookmatching down the middle. The granite yard needs to have two slabs from the same batch that are bookmatched, i.e., mirror image. A bookmatched island can be gorgeous. If the granite has more of an all-over pattern, then a good, tight, neat seam isn't that visible anyway.


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RE: Facts about Granite Slab Quality Variables

I posted the question earlier about sealing or not sealing some granites. I mentioned that the Black Pearl in our bathroom was not sealed but it has worn well. However, the other day DH pointed out that there are some dull spots in couple spots close to the edge of his sink----one of them near the soap dispenser. I've cleaned with alcohol and water, but as soon as it is buffed dry you can see and feel that it is dull. I wouldn't say it's rough, as it's smooth, but it's just dull. They did not seal the granite when it was installed, but for our bathroom we bought a pre-fab counter to save money. Could it be that it was pre-sealed somehow? Any ideas what to do about the dull patches?

I am particularly concerned because we are supposed to have Black Pearl installed in our kitchen. We just went and looked at the slabs the other day. Now I don't know what to do---seal or don't seal? Also the fabricators offer a fifteen-year sealer. If I'm going to have it sealed, I think I'd like the fifteen-year sealer, because I worry about resealing and putting on another coat of sealer that isn't compatible with the first sealer. Another reason is that I have very bad asthma/reactive airway and have to be sure to be gone when the sealer is applied. The fewer times we need to do that the better. Nevertheless, I also wonder what makes one sealer good for a year or two and another for fifteen? Is there really something better about the fifteen-year sealer, or is it just hype?

I've been waiting and saving for years to get new countertops in my kitchen, and I'd like to get it right the first time.


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RE: Facts about Granite Slab Quality Variables

The 15 year sealer is a gimmick to provide an up charge and sell you piece of mind. Read the fine print and if you screw up on the registration process your warranty is null and void. The 15 year sealer isn't a bad product but it a load of bull in a pretty marketed package.


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RE: Facts about Granite Slab Quality Variables

Sail-away - if you are going to use alcohol to clean granite counters, it should just be a drop or two mixed with water. Alcohol is used on granite counters for people who want alcohol's antibacterial properties, not to remove spots. I read on a stone website that f you buy a commercial granite cleaner, it might contain alcohol at 5% at most. So, you may have made your counter worse if you used a lot of alcohol. Anyway, it could be that the spots on your bathroom counter are etching caused by toothpaste and/or mouthwash. I have some etching in my kids' bathroom caused by acne medications. I don't really notice it any more.

I agree with Coloradoroots that the 15-year sealer is a marketing ploy to make you pay many times more than you would if you went to Home Depot and bought sealer that would last you years, with one application per year.

And my final point is that sealer is to prevent staining. Nothing prevents etching, though I am surprised that a stone as dense as Black Pearl etched. So I looked at a couple of older threads - I am linking one below that is specific to Black Pearl. In particular go to SROSEN's post toward the end - he is a stone refinisher.

Here is a link that might be useful: Thread about Black Pearl Granite

This post was edited by shannonplus2 on Fri, Mar 15, 13 at 9:06


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RE: Facts about Granite Slab Quality Variables

Hi,
Since this is a very informative thread on granites, I'd like to attach my questions here. I'm looking for 2 granite types with low absorbency rate and even movements or crystal structures / pattern.

1. Granite in beige or golden color for the new kitchen countertop.
2. Granite in white or light grey for the new bathroom vanity countertops. By white, I don't mean overall white like ceramic as it's not possible with natural granites. I mean to find one that overall, with its Chrystal structure, appears white or light grey.

I have also received interesting information that some famous granites from Indian like cashmir white, ivory colors, Jumparana, Shivakashi, Ghibli, will become very rare on the market. This is due the plan by the Indian government to cut down the production and import of granites. I was given this information by a local dealer, and have no verification of this information other than what he told me. For the given reason, I'd rather avoid a granite from Indian to avoid availability issue later in case we need to obtain some more granite or need some amount for repair work in the future.

Any recommendations would be very much appreciated.

Thank you very much.
H-C


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