Engineered stone is a composite material made of crushed stone bound together by an adhesive, (most commonly polymer resin)
Engineered stone is also commonly referred to as agglomerate or agglomerated stone, the last term being that recognized by European Standards (EN 14618), although to add to the terminological confusion, this standard also includes materials manufactured with a cementitious binder. The quartz version (which end consumers are much more likely to directly deal with) is commonly known as 'quartz surface' or just 'quartz'.
Breton S.P.A., a privately held company of Treviso, Italy, that developed large-scale Breton method in 1960s, is the dominant supplier of equipment for making engineered stone.
In 1987 the Israeli company CaesarStone bought the first Breton plant using new technology for the production of large 125 by 308 cm slabs (about 49 by 121 in.). At first the plant was designed to use granulated marble, but it was very quickly converted to produce slabs made of silica sand and then ground quartz, in consideration of the fantastic results obtained in the Welsh plant. It was a great success for the company, which now has four plants with plans to install two more.
In Spain, Cosentino, who had bought a plant to use waste from their Macael white marble quarry in 1989, later switched production to quartz with its Silestone product, and this (along with effective marketing in North America) resulted in exponential growth. Cosentino’s first plant was soon followed by a second, a third, a forth, and the company now owns 11 and is the largest producer of quartz surfacing in the world.
Although Breton was the original manufacturer of moulding equipment and still holds multiple international patents on the process, there are now several other companies producing similar machinery.
Stone aggregates is the major filler, although other material like colored glass, shells, metals, or mirrors might be added. A typical resin based material will consist of 93% stone aggregates by weight and 7% resin (66% quartz and 34% resin by volume) . Different types of resins are used by different manufacturers. Epoxy and polyester resin are the most common types. Chemicals such as UV absorbers and stabilizers are added. To aid curing, hydrogen peroxide is added.
Compaction by vi-bro compression vacuum process uses elastomeric molds in which a crushed stone/resin mix is cast on a moving belt. The mixture of approximately 93% stone aggregates and 7% polyester resin by weight (66% quartz and 34% resin by volume) is heated and compressed under vacuum in a large press. The vibration helps compact the mixture and results in an isotropic slab with virtually no porosity Engineered stone is then processed in basically the same manner as its natural counterpart.
Some companies import boulders themselves to crush into agglomerates (stone powders) of various grain size for their products, others simply buy already-crushed stone powders.
Engineered stone is typically worked in the same way as natural stone using a water jet cutter or a diamond blade. This is in contrast with solid surface materials which can be cut with regular saws.
The material can be produced in either 12 mm, 20 mm or 30 mm thicknesses. The most common slab format is 3040 mm x 1440 mm for Quartz and 3050 mm x 1240 mm for Breton-based marbles, but other sizes like 3040 mm x 1650 mm are produced according to market demand.
Engineered stone is non porous, more flexible, and harder than many types of natural stone. Since it has a uniform internal structure, it does not have hidden cracks or flaws that may exist in natural stone and also has a color/pattern consistency from slab to slab. Polyester resin binding agents allow some flexibility, preventing cracking under flexural pressure. But, the binding agents often continue to harden, leading to a loss of flexural strength over time. The polyester resins are not completely UV stable and engineered stone should not be used in outdoor applications. Continuous exposure to UV can cause discoloration of the stone, and breakdown of the resin binder.
The material is sometimes damaged by direct application of heat. Quartz engineered stone is less heat resistant than other stone surfaces including most granite, marble and limestone; but is not affected by temperatures lower than 150 °C (300 °F). Quartz engineered stone can be damaged by sudden temperature changes. Manufacturers recommend that hot pots and pans never be placed directly on the surface, and that a hot pad or trivet is used under portable cooking units.