To begin, let me say that I am not biased for or against Quartz Stone. I’ve been in the natural stone industry for over 20 years, but I also own www.QuartzStone.com because I believe in marketing and supporting Quartz Stone and its design quality uses.

Quartz Stone is a manmade product composed of an epoxy resin (usually polyester-based) and fine quartz aggregate. The unwritten industry standard for suppliers is to combine approximately 93% natural quartz aggregate with 7% epoxy resin (by weight). These percentages are by weight, not volume, so don’t think that you’ve got a slab of quartz there! It does not much resin to hold the quartz together and the weight/volume ratio is much higher for quartz than resin. I have personally made many mix variations of Quartz Stone and found that the 7% resin is sufficient when the aggregate is not too small. More resin is needed for smaller aggregate (again, by weight, not volume). The composition is simple, but the process and equipment to produce it is complex and expensive. Since there are hundreds of quality manufacturers of the aggregate and the resins, I would say the ‘composition’ of quartz stone represents about 20% of a supplier’s quality rating. The other 80% comes from its own methods and procedures to produce slabs or blocks of the resin.

There are many patents that surround the manufacturing of this product, and most of them are owned by one company in Italy. Nonetheless, after inspecting many factories in China, I believe that a quality quartz stone product can be produced without the patented machinery and technology developed in Italy.

China has some good suppliers and many poor ones. None of them open their factory to inspection without developing a business friendship first. Patent infringement speculation and concerns to maintain their assumed competitive advantage will prevent most from passing by the manufacturing line. I have seen the production in three large factories and the serious plants use variations of vibrating molds and vacuums. This is no surprise since removing the trapped air in the product is the primary concern, in front of removing impurities and accurate mixing of the resin according to adjusted atmospheric conditions. The main protest from competitors in Italy, Spain, Israel, and the USA is that the Chinese technology is so inferior that an additional set of surface applied resin is required. I have seen this being done, and when done the right way, I find it comparable to the resin coating now put on Grade D exotic granites, worldwide.

I don’t find this to be a problem but it is not uncommon to have micro holes appear at the edges once the slabs are cut, so a fabricator should be prepared to fill the edges before finishing, just as done with Class D granites. The resin should match the type used in the Quartz Stone.

For individual kitchen countertops projects, I might say stay with the name brands such as Silestone, Caesarstone, Zodiac, and Cambria because their customer service is more end-user friendly. For the sophisticated fabricator with a large Quartz Stone project, you can probably save about 25% on your material costs, plus the big money is saved when a Chinese supplier is combined with a reputable Chinese fabricator. Best to hire a consultant to handle that transaction or be prepared to get on a plane to China several times during your project.

Another consideration is sunlight. All polyester based Quartz Stone fades from sunlight. Some of the name brands have made significant improvement over the past few years to include UV inhibitors in their products, which reduce the affect substantially. However, they are still not recommended for exterior installations.

I will try to update this article as questions come in.

Tom Cordova
4/20/2010