In the Stone Business, You Get What You Pay For!!

In the March 2010 issue of "Stone Business" magazine, there was an interesting article titled "Hard Lessons" by Tom McNall.  In summary, a stone company had won the low bid for a high end condo kitchen by using inferior material.  Once installed the customer was having problems with the tops.  Every time water was applied to the tops they turned gray.  The stone company said the tops needed to be sealed, there was to much wax on the tops or the water treatment facility was using to much chlorine.  So the company sent out a specialist (the author of this article).  As he suspected, none of the above was true.  The stone company had masqueraded Gray Absolute granite, a cheaper and lower quality stone, as Black Absolute.  There was nothing to fix the color except replace the tops.  One of the most important points the author wanted the reader to take with them is "in the stone business, you get what you pay for!  I can't count the number of stories on installation failures that all begin with the same phrase:  I got a really good deal on this stone." 

This article made us want to take a moment and explain the Stone Soundness Classifications.  So next time the deal looks to good to be true, you'll have the knowledge to know if it is.

Group A consists of stone with uniform and favorable working qualities.  They contain no geological flaws or voids.  This group does not require surface work, filling, or patching.  These stones work well in exterior and interior applications.

Group B is similar to group A but all the impurities, such as clay or silt, have not changed into other minerals.  Small holes and voids are to be expected and are a characteristic of this group.  These holes and voids are usually filled with Epoxy or polyester resin.  The filling should be undetectable and "glass" smooth.  Group B can be used for interior or exterior applications.

Group C have some variations in working qualities.  Geological flaws, voids, veins, and lines of separation are common.  This group consists of some of the most colorful stones.  The holes and structural flaws are usually so significant that is standard practice to repair them with using reinforcing, liners, filling with resin or cement, fabricating corners or missing parts with terrazzo and resin, and all other work to hold the stone together to yield a finished product.  On completion most of the repairs are visible and apparent.  These stone are not suitable for exterior use.

Group D is similar to group C but containing a larger portion of natural faults.  The same finishing as group C is required.  Only a few stone carry this designation.  It is reserved for very laborious Group C stones.