Quality in Engineered Stone

Engineered stone like every other product has quality standards, although at the current moment the CE marking is not ready for engineered stone slabs. On this post I want to show you, common industrial problems with engineered stone, you will see things that should not arrive at your warehouse, let alone in someone's household.
Engineered stone being a man made stone or as some like to call it an artificial stone, it's rather complex to make a perfect piece of engineered stone, many little things may go wrong during production, warehousing and shipping.
Here is a list of the most common problems that may be visable on your engineered stone slab or tile:
  1. White superficial dust/veins: this superficial white dust is due to bad formulation or uneven distribution of the mixture, what happened was that the mixture was not done correctly, being that in the mixture some dry unmixed quartz dust was incorporated into the slab. In the photo you will see a vein effect, after the dust is cleaned the tile will not have a perfect surface.
  2. Cracking: you may receive pieces or even slabs with small tiny crack that you can barely see. These are due to an improper chemical reaction, normally the hardening process of resin is a very controlled chemical process, but many factors can either accelerate or slow down the reaction.
  3. Tiny pin holes: Unfortunately the photos I have can't give you a correct idea of this, as the definition is not as good as I need to actually show you it. But basically it characterized by small pin holes on the slab surface, it's really difficult to see, and sometimes you may need the right lighting angle to correctly visualize it. These little pin holes with time will accumulate dirt, and the engineered stone will quickly look very awful, although in dark colours this negative may be hidden. In theory a slab by slab production process should be less porous than a block production process, so if you deal with engineered marble it may be a good thing to look out for. Some manufacturers end up resining the surface to hide this defect, but many times the defect is so small that even resin will have problems solving it.
  4. Shade differences in the same slab: I had once a project where I learned a very painful lesson, we cut the counters from the same slab (dark blue with mirror chips), and so we did not worry about checking the shade, as we all did assume that the same slab would have an even mixture. Truth is that polishing also has an important effect on the surfaces shade. Applying those miraculous chemical products will improve the shade difference, but will not solve it.

  5. Slab length: I've learned through experience not to believe in everything people tell me, so I usually do a visual inspection of my cargo, a handy measuring tape is essential, and don't be surprised if you find what I found (in the photo you may see that the slab has 303 cm, and I was paying 307).
  6. Warped slabs: engineered quartz slabs is far from being plastic, as it has more than 90% natural stone, as everyone knows most materials warp if they are not warehoused properly. And engineered stone may warp slightly more than your common natural stones. So make sure to properly warehouse you engineered stone slab and tile.
  7. Slab thickness: as I mentioned the length, the thickness may be a more common defect, everyone who has done some engineered quartz countertops, know that an uneven thickness in the same slab or between slabs, will cause adjustment problems. To actually measure the thickness of a slab, besides the measuring equipment, you also need to take the measurement of the slab in several points, 6 are just enough to conclude if the thickness is according to your tolerances.
  8. Tile mitre is a common problem, a quick check can be made by facing two polished surfaces and trying to even out the sides, just by putting the tiles standing on a flat surface you will quickly figure out if the tiles are well cut. Avoid these problems before they get to difficult to handle, these types of controls are in some factories made automatically by machinery, but many factories use sampling methods to do such test. 
  9. Engineered stone tile cut imperfection: equipment and tooling age rather quickly, if you have automatic cutting lines you may have several tiles to handle per minute, which in some factories may leave quality inspection to the side to deal with the current problem.
  10. Engineered stone tile uneven bevelling: the correct way to bevel a tile and to guarantee a perfect bevel, is bevelling it with the polishes surface facing down. However most factories do bevel it with the polished surface facing up, which means any little deviation in thickness will be an imperfection in bevelling. It can be a possible problem in some cases where quality control is not taken seriously. 
  11. Grey smudges: these occur more frequently in engineered marble than in engineered quartz, and is mainly due to the production process.
  12. Surface scratches: you find several types of surface scratches, some due to bad packing others due to manufacturing. One thing for certain, it's easier to find scratched material on engineered marble, than engineered quartz, the hardness of marble is relatively low and can be scratched by many materials. Regarding packaging engineered marble and engineered quartz should be done with the polished surface facing each other. When dealing with engineered marble tiles, especially on long voyages, if their is not protection in between polished surface, micro scratches might appear on the end of the tiles. Packing has to be very well done to avoid these situations, the trepidation during transportation will gradually make friction between the tiles and any micro dust will become an abrasive. The other often situation, and common to engineered marble and engineered quartz are micro scratches on the polished surface, namely in dark colours. Very frequently small particles of sand/dust appear during the polishing process (in saturated water for example) and they create defects on the surface, which sometimes may not be effectiently detected by visual inspection.


      What is a CE marking and what does it mean?

      Many may question what is a CE marking and what does it stand for? CE is short form for Conformité Européenne, i.e., European Conformity, you may find many products in you household with this marking, it means that the product complies with European Directives for that product, these may refer to safety, health, consumer safety, and many other things that the product, manufacturer and other market agents have to comply with.
      Buying or selling building materials in Europe, requires that the given product is fit for its intended use, basically has to comply with requirements included in the Building Materials Regulation 89/106/CEE. These requirements are of several types, namely complies with consumer health and safety standards, therefore references are defined for:
      • Mechanical resistance and stability
      • Resistance to Fire
      • Hygiene, health and environment: which may include  noise, energy consumption and heat retention
      The CE marking is based on EC directives, and are used as European Standards, therefore every state member of the European Community will have to comply with these norms. These basically guarantee that the product is fit for use according to the defined product standards.
      Some products have to be marked with the CE symbol themselves, however it’s not obligatory for all products, each type of product has the marking needed in the standards. The standards themselves besides defining the testing and other issues, also may be specific regarding packing and product marking.

      To be able to buy and sell in the European Community, the product should comply with the CE marking, this insures that it complies with European law.

      Agglomerate stone as mentioned in a prior post has already some CE marking standards in application as of the 1st of January 2010, namely the UNI EN 15285 which refers to modular tiles for flooring and stairs (internal and external). This standard was published in July 2008, and defines the agglomerate stone requirements and testing methods for modular tiles used in flooring and stairs (internal and external).

      In truth these standards mean, that any product made or sold in Europe will have specific physical properties to be considered a agglomerate stone for modular tile use. If the stone doesn’t comply with the standard it may not be sold as CE complying, which may mean it be banned from the market, or not considered as a valid option for a construction project.
      A product that doesn’t comply with CE marking can’t be sold as being, in this particular case, an agglomerate stone modular tile. A certified product has to undergo several testing and manufacturing procedures to ensure compliance with the standards. So we have controls in factory and also by certified laboratories, these entities guarantee the product quality and therefore compliance with the CE marking standard. Traceability is one of the in factory controls, from raw materials to the end product, many in factory procedures are made to insure product quality.
      Unfortunately non CE marked material does appear in some work sites, not every European member has the correct inspection settled for these products. In many countries, the CE marking is not checked, and at many construction sites you may find un-marked material. In time most of these abnormal situations will slowly disappear and making the CE marking standard a good thing for consumers as it insures quality to the end buyer, who in many cases have in the past not received high quality products.