Engineered Quartz Worktops - Technical - Environmental Features
Technical and Environmental Features of Engineered Quartz Worktops Engineered Quartz Worktops - Technical & Environmental Features
In the last couple of decades engineered quartz worktops have taken over as a main choice among leading interior designers and kitchen designers. It used to be natural stone that ruled the industry, however, due to certain downsides, the use of marble and granite worktops has diminished.
Here we're looking at technical and physical properties of quartz through various scientific tests.
Quartz is a natural silicate material mainly consisting of SiO2 (crystalline silicon dioxide). Because it's so common and wide-spread, engineered quartz worktops come out cheaper than natural stone, despite quartz being rather labour-intensive. As quartz only occurs in small clusters, you can't make slabs out of it. That's why it's crushed in small pieces and mixed with polyester resin to form slabs.
The resulting material is superior to agglomerated marble in both abrasion resistance, acid resistance and hardness. Also, engineered quartz displays virtually no water absorption qualities which is something you can't say about marble and other natural stone kitchen worktops that often suffer with water ingress which leads to discolouration deterioration.
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To be used in residential applications, quartz has to fulfil both aesthetical and utilitarian expectations and sometimes overcome the kitchen designers' and interior designers' natural scepticism about a new material. It was recently proved that the material also meets more stringent non-residential building code requirements. More interestingly, designers can use quartz surfacing for both horizontal and vertical applications in other words - any interior where a smooth, strong, high-performance yet low-maintenance surface is required.
It's worth keeping in mind that engineered quartz worktops can degrade when exposed to strong ultraviolet light, however, in most indoor applications it should last at least 20 years.
What is Engineered Quartz
Quartz slabs are composite made of approximately 93% natural quartz aggregate chips, which is the most abundant mineral that is found in the earth’s crust. Much like concrete, it consists of a high percentage aggregate and binder - silica sand - held together by a thermoplastic polyester resin.
The aggregate and resin are blended with mineral oxide pigments and other fade-resistant colorants. The mixture is formed into a high-density slab through a combination of intense vibration, high pressure, and vacuum. It is then heated and vibrated until the resin fuses the aggregates. After cooling, the slab is either polished to a smooth surface or given a decorative finish.
Selection of pigmentation and the quartz's colour, size, and gradation, can produce an enormous range of visual effects. Some manufacturer models of quartz surfacing resemble granite, limestone, or other natural stones, whereas others emulate high-quality architectural portland cement concrete. Some types of quartz can even look like terrazzo due to the presence of polished stone chips in a coloured matrix. Certain brands have a distinctive appearance that is impossible to achieve with other materials.
Depending on the brand, the quartz aggregate chips range in diameter about 4 mm maximum to extremely fine grains of silica sand. The finest aggregate produces an aesthetic similar to grainless stone yet maintains the lustre and light-holding ability of quartz crystal. In contrast to most natural stones marked by veining and variations in coloration, quartz surfacing can be controlled to provide a uniform appearance across a slab and between slabs made within a manufacturer’s production run.
Quartz’s appearance varies widely, from familiar transparent crystals such as clear quartz, rose quartz, smoky quartz, and amethyst, to multi-coloured, translucent and semi-translucent agates. Quartz can also come in the opaque earth tones of jasper, or the yellows, reds, browns, and greens of citrines and prasiolites. Like most transparent and translucent crystalline materials, quartz reflects some light at the surface, but also transmits it to the interior where it reflects from internal crystal planes, for a sparkling and glowing effect. The translucent resin in quartz surfacing works well with these properties, and quartz surfacing often produces a sense of depth and light.
Kitchen worktop slabs can be made to meet requirements of local or regional stone fabricators equipped with diamond cutting and polishing tools, as well as wet cutting equipment. However, quartz surfacing is much easier to handle than natural stone, because its inherent strength reduces the likelihood of a slab cracking under its own weight when lifted.
Engineered Quartz Videos
Watch this short video to see how much effort goes into your quartz worktops:
Testing Engineered Quartz Worktops
Quartz is harder than natural building stones, as measured by the Mohs scale of mineral hardness. As quartz has a Mohs hardness of 7, only a few materials-such as topaz (Mohs 8) and diamond (Mohs 10) are hard enough to scratch it. In comparison, most other materials are not hard enough to do so. For example, the average Mohs values for other materials are:
Most typical household or workplace items cannot scratch quartz in daily use unless your utensils are made of diamond.
The composite retains much of the toughness of quartz, due to the high proportion of stone and the nature of the manufacturing process. Vibration, temperature and pressure cause the stone’s crystal facets to align, and subsequent grinding and polishing tend to reveal more aggregate on the surface. Scratches in the interstitial resin are short, and generally not visible. The resin‘s ductility also contributes to the material's impact resistance.
Wear and Tear
Quartz worktops tested passed Section 5.3, “Wear and Cleanability,” of American National Standards Institute (ANSI) Z 124.6
This test involves 10,000 cycles of scrubbing with abrasive suspension followed by 25 cycles of rubbing with dirt. After ensuant cleaning, light reflectance was reduced by 3% at most - a result well within the 5% reduction acceptable under the standard.
Quartz is highly stain-resistant due to the intrinsic impermeability of the quartz aggregate and polymer resin, as well as the manufacturing process that forms the ingredients into a dense slab practically free of gaps and pores.
In accordance with Section 5.2, “Stain Resistance,” under ANSI Z 124.6, the tests exposed quartz surfacing for 16 hours to typical products that end up ruining kitchen worktops in real life application:
- beet juice
- hair dye
Only ink and lipstick produced any staining at all and occurred only in certain extremely light - coloured brands. Regardless, these slight stains still met ANSI requirements because they could be cleaned with standard cleaning liquids.
To verify resistance to chemical exposure, quartz slabs were tested in accordance with Section 5.5, “Chemical Resistance,” under ANSI Z 124.6. The material was unaffected when exposed to solutions such as:
naphtha; ethyl alcohol; ammonia; citric acid; urea; acetone; vinegar, hydrogen peroxide; lye; bleach pine oil.
This performance data may not apply to products by all manufacturers. For example, at least two USA-based manufacturers of quartz surfacing warn against any exposure to bleach.
Even more stringent is ASTM International C 650, Resistance of Ceramic Tile to Chemical Substances, which involves 24-hour exposure to chemicals. In this testing, quartz surfacing remained unaffected by solutions of:
- acetic acid
- ammonium chloride
- citric acid
- lactic acid
- phosphoric acid
- sulfamic acid
- sodium hypochlorite
- hydrochloric acid
- 3% potassium hydroxide solution
Although some quartz worktop brands were moderately etched or discoloured by 24-hour exposure to 10% potassium hydroxide solution, it is highly unlikely quartz slab or any decorative quartz surfacing would be considered in industrial situations where such prolonged contact could occur.
Quartz kitchen worktops don't need to be maintained with sealers, waxes, or polishes. The way other natural kitchen worktop materials do. Granite and marble are relatively porous and require frequent sealing to resist staining by common substances like cooking oil and wine.
Sustainable quartz kitchen worktops and their certification credentials
Quartz worktops can be considered a sustainable material. Extraction processes have relatively minimal environmental impact, as quartz’s raw material is rarely mined expressly for use as a surfacing product. Instead, crushed chips and chunks of quartz are generally reclaimed waste products of other mining operations-for example, gold is found in quartz veins. Fine aggregate is produced naturally-silica sand is an abundant resource.
It is also a low-volatile organic compound (VOC)-emitting material, with several manufacturers qualifying for both Greenguard’s Indoor Air Quality Certification and its more stringent Children & Schools Certification, which tests performance against the standards set forth in the California Department of Health Services Standard Practice CA 01350-Special Environmental Requirements.
These indoor air quality (IAQ) certifications qualify quartz surfacing products to contribute to earning credits in U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design Commercial Interiors (LEEDiCI) program, such as Indoor Environmental Quality (EQ) Credit 4.5, Low-emitting Materials-Systems Furniture and Seating, the Collaborative for High Performance Schools (CHPS) Best Practices Manual for K-12 Schools, and other green building programs.
Quartz kitchen worktops do not require application of sealants, helping maintain air quality. Other surfaces, such as natural stone and concrete, need to be resealed frequently; the VOC-emitting sealants used have negative environmental impacts over the materials’ service lives. Unless misused or subjected to abuse, quartz surfacing can be expected to retain its good looks indefinitely; lifetime limited warranties are available from some manufacturers.
In most applications, close examination of quartz surfacing test data is unnecessary-the product‘s performance in common applications is well-documented and many of its salient characteristics can be easily established.‘ Yet whenever a designer uses a material in a creative new way, professional standards require critical assessment of claims published by various manufacturers.
Quartz worktops satisfy the strict hygienic requirements of foodservice and healthcare facilities. Moreover, quartz surfacing offers an aesthetic that complements contemporary architectural styles. This engineered stone consists of crushed quartz particles in a thermoplastic binder. In the two decades since its invention, millions of square feet have been installed worldwide.
Quartz was introduced to North America and Western Europe in the late 1990s, concurrent with the onset of the fashion for granite worktops. While its wide palette of colours and patterns secured a place in the design professional’s repertoire, quartz surfacing’s continuing popularity stems from physical performance that rivals, if not exceeds, other common surface materials. Moreover, its installed cost is competitive with natural stone and other high quality finishes. The material’s sustainability further adds to its appeal.
Additionally, it complies with the EU construction material regulations in terms of fire resistance classes. It was tested by AFITILICOF Centre of Fire Testing and Research (Association for the Promotion of Research and Fire Safety Technology) regulation 653 IMO FTPC Code Resolution MSC 61.
It is allowed to prepare food directly on a quartz surface because it is approved by both National Health and Safety Foundation – a non-profit consumer organisation based in the USA. Also, all quartz worktops are marked with the familiar glass and fork mark – the European Regulation food certificate according to CE 1935/2004.
This point was evident when you compare results of their testing to published product performance data. As mentioned, the flexural strength of quartz surfacing was found to lie between 44,800 and 74,250 kPa (6500 and 10,770 psi), a significantly broad range. On examination, it can be determined this spread could he explained by the quartz aggregate’s size in the model tested. The flexural strength of quartz surfacing varies inversely with aggregate size smaller-aggregate materials have higher flexural strength.
Strength and versatility
Marble and granite have little flexural strength. For example, granite‘s flexural strength is generally between 6900 and 13,800 kPa (1000 and 2000 psi)-this low strength makes natural stone highly vulnerable to breakage during handling and fabrication. In comparison, quartz material tested according to ASTM C 880, Flexural Strength of Dimension Stone, ranges from 44,800 to 74,250 kPa (6500 to 10,770 psi). This strength may enable use of thinner materials for reduced weight.
Natural materials are also inconsistent in strength, even across the breadth of an individual sample. No two pieces of granite are the same; any piece may have flaws and weak points. As a manufactured material, quartz surfacing has uniform strength within each piece; its strength is consistent between samples of the same type or model of material. Thin natural stone worktops must be installed atop full underlayment support due to the stone’s strength limitations. In contrast, quartz surfacing of the same thickness can be installed with only partial underlayment support, such as a wood frame around the top of base cabinets.
Quartz worktop is also strong enough to permit cantilevered worktop installations-with full perimeter support at the cabinet edge, 20-mm thickness quartz surfacing can sustain a 300mm unsupported overhang with ordinary residential loads, and a 30-mm thickness can support an overhang of 400 mm.
With corbels or brackets every 600 mm, this overhang can increase to 500 mm for 20-mm material, and 600 mm for thicknesses of 30 mm at typical residential loads.
As the material contains a thermoplastic, heat resistance is a concern. Tests prove quartz surfacing can resist 20 minutes of exposure to a 177 C vessel, or to boiling water, without changing colour or surface finish. Nevertheless, most manufacturers caution against placing hot cookware directly on quartz worktops and recommend using insulated hot pads or trivets.
Quartz Worktops Safety Factors
Material safety is an important issue, especially in institutional applications. On the basis of surface burning characteristics, we found quartz qualifies as Class 1 by the International Code Council (ICC) and Class A per the National Fire Protection Association (NFPA), permitting its use in buildings with stringent life safety requirements. Moreover, quartz surfacing resists damage from burning cigarettes. Its emissions under fire conditions are only one- seventh as toxic as those of burning wood, easily passing New York City code requirements.
The material is naturally resistant to fungal growth and its dense, non-porous surface offers little room for bacteria to flourish. Consequently, many quartz surfacing products are accepted under NSF International 51, Food Equipment Materials, as ‘splash zone’-approved for areas subject to food spattering and spills (e.g. backsplashes and other vertical surfaces). Certain models are also ‘food zone’- approved for direct food contact, such as worktops and serving lines. In commercial food venues, only NSF-listed products should be selected.
Concerns about radioactive radon emissions have induced some quartz surfacing manufacturers to test their materials. Testing conducted by Israel’s Soreq Nuclear Research Centre (NRC) using the procedure set forth in ANSI/Institute of Electrical and Electronics Engineers (IEEE) N 4214-1999, American National Standard for Calibration and Use of Germanium Spectrometers for the Measurement of Gamma ray Emission Rates of Radionuclides, found the product fulfils the European Commission’s standard "Radiation Protection No. 112, Radiological Protection Principles Concerning the Natural Radioactivity of Building Materials."
Although it now seems obvious, this characteristic of quartz surfacing was not acknowledged in most manufacturers' literature. For example, one producer says its product has a Flexural strength greater than 36,542 kPa (5300 psi), whereas another states its product has one of 40.265 kPa (5840) psi-without regard for grain size.
The engineered quartz industry has not yet developed uniform levels of disclosure about its products properties. As it is impractical to review test data for all characteristics of products, specifiers must decide when to request test reports and how to interpret their findings. In applications where performance is critical, model-specific proprietary specifications or detailed performance specifications should be used as the basis for construction documents.
In addition to being durable, quartz is also recyclable at the end of its service. One manufacturer has recently started a program to collect and recycle scraps produced during local fabrication of quartz surfacing or following building decommissioning. Neither the quartz mineral nor the thermoplastic resin suffers any degradation during recycling, and the energy needed to crush and reuse the materials is minimal. The number of recycling programs in effect is expected to increase rapidly in the coming years.
Quartz constantly tops the Consumer Reports kitchen guides. It's basically, the American equivalent of Which? consumer guide. They carry out surveys evaluating materials by submitting them to rigorous testing. They test and score kitchen worktops in five disciplines: resistance to stains, cuts, heat, abrasion and blunt impact. Quartz always comes on top. Most recently, it scored 84 out of 100.
Where quartz slabs can be used is largely a matter of vision. The material itself is versatile and suitable for various applications. As a kitchen worktop, it is a good choice for the hospitality industry - it can endure hard wear with little maintenance, cutting costs both in hotel rooms and public areas. It is also suitable for food handling areas. Furthermore, easy cleaning and resistance to fungal and bacterial infestation make it a strong possibility in medical and educational environments.
In vertical applications, the lighter-weight, thinner material has strong potential. As wall cladding, wainscoting, baseboard, or doorframe trim, quartz surfacing can provide a unique contemporary touch or traditional stone-like look. It can even be used in fireplace surrounds with proper attention to sufficient isolation from heat, as defined in NFPA 211, Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-burning Appliances.
In restrooms, quartz surfacing is an excellent choice for shower and bath enclosures. It also provides a distinctive option for toilet compartment partitions that can coordinate with quartz surfacing on walls and worktops to create an integrated suite of finishes.
Decorative applications are as wide as your imagination. The material can be finished on one or both sides and perforated, offering an intriguing look for railings and balusters. Indoor water features can be constructed or decorated with one or more varieties of quartz surfacing, creating an optical interaction of water and crystal. Wall surfaces can be etched with custom designs. Undoubtedly, the various characteristics of quartz surfacing offer endless possibilities in the design/construction sector.