Engineered Stone: What is it?
Engineered Stone is not a popular term among its manufacturers. They prefer the term “Quartz” which sounds much more natural. Ceaserstone, Stone Italiana, Smart Stone, Quantum Quartz, are a few of the more popular engineered quartz surfaces offered here in Australia.
Engineered quartz slabs are all, for the most part, manufactured the same. They are all produced using the same production line equipment, either the Breton system which was created in 1977, or another system closely modelled after the Breton system. The ingredients are blended dry; approximately 93% crushed dry stone material and 7% dry polyester epoxy resin and dyes. Then it goes through the steps; mixing, blending, homogenising, and moulding. The slabs are then compressed with 100 tonnes of pressure and cured at a temperature of 90C for 30 minutes. Finally, there is a stringent regime of quality control to ensure the consistency in finish and colour, which is vitally important as consistency is the main selling point with engineered stone.
If you would like to learn more about manufacturing you can watch the entire process here: http://www.youtube.com/watch?v=Tv6bhy4WT8g
The engineered quartz finished product has some very attractive qualities for the tradesman, with a very high Flexural Strength (ASTM C-880), it will not easily break under stress or if it is mishandled, and a high Abrasion Resistance (ASTM C-241) means it is difficult to accidentally scratch. It also has a very low Absorption Rate (ASTM C-97), which means it will not easily stain and does not require sealing.
There are many colours and textures to chose from, and the colour consistency is an attractive quality for designers, providing a low degree of risk…the client will get a bench top that looks exactly like the sample square they were shown. This cannot always be said for natural stone.
Problems with Engineered Stone
Because the matrix is polyester resin engineered stone is not suitable for external applications, which will break down the resin due to UV exposure. Therefore, granite is recommended for external applications, and epoxy resin glue ups for all edgework.
Engineered stone can also burn if hot objects are placed on them, like a frying pan from a hot stove, this is due to the resin binders which are not heat resistant.
Engineered stone will not etch because both the quartz matrix and the resin binders are not reactive to common acids. Even though limestone and marble is acid sensitive, the marble/limestone based engineered stone is not acid sensitive because it is so saturated with the resin binders, it actually changes the structure of the material- it’s not a natural stone.Engineered stones can also develop “resin scratches” which appear to be small scratches in the stone, but are actually just in the resin binder, which is much softer. Tip: This is can be repaired by buffing with fine steel wool and acetone.
Engineered stones can also develop “resin scratches” which appear to be small scratches in the stone, but are actually just in the resin binder, which is much softer. Tip: This is can be repaired by buffing with fine steel wool and acetone. In comparison, a true granite will not burn or etch and is almost impossible to scratch (depending on the type), but does require sealing in many varieties (all Juperanas, Kashmere, Ubatuba).
Seams are easily disguised with engineered stone as the cuts can be very smooth and joined together nicely. Epoxy seams appear to look better because the colours are easy to match and are already part of the material. Flat polishing seams can be a problem because the 3000 grit diamond polished finish will not match the factory finish, which has a freckled look. There is a three part kit one can purchase from the US to perform this, but it is $300 and a bit of a drama to do. This is also what makes scratch repairs such a problem on engineered stone. There is a way to return the diamond polished finish to a factory look, but that is a trade secret I will hang on to.
All in all the appearance does have a manufactured look which is easily recognised to a discerning eye when compared to natural stone. It lacks the unique look of granite, that each granite piece is an original work of art from nature, and each bench will not look exactly like the house next door. The manufacturing, however, provides a great deal of control- you will know exactly what the bench will look like, and this offers security.
The difference in regards to design is simply this: engineered stone is safe and natural stone is art, and art is objective. But you can love art to a greater degree.
From a practical standpoint; both are similar in regards to durability, and engineered stone is much better for the fabricator due to the much lower breakage rate. Engineered stone will however burn, and it can discolour (I have restored some very badly stained engineered stone surfaces). Granite is superior in regards to longevity, will not scratch as easily, will not burn, and is not UV sensitive. But it also can stain and must be sealed with a high quality impregnating sealer.
So there is a lot to consider. The choice will ultimately come from the client, and being properly educated will help them get what they’re after. I hope this will help.