The most frequent common denominator seen by expert witnesses when inspecting cracked mosaic glass tiles in swimming pools, has been the use of recycled glass as a raw material.
Beyond their control
Recycled glass is supplied to the tile manufacturers already ground up. This ground glass is know as cullet. The standards established by the recycling industry permit cullet to contain impurities.
The Glass Packaging Institute standards state: "Some recycled glass containers are not able to be used in the manufacture of new glass bottles and jars or to make fiberglass. This may be because there is too much contamination or the recycled glass pieces are too small to meet manufacturing specifications.... This recovered glass is then used for non-container glass products. These "secondary" uses for recycled container glass can include tile, filtration, sand blasting, concrete pavements and parking lots."
They are saying that contaminated cullet should be sent to glass tile manufacturers!
The processing of cullet attempts to remove impurities. By their own admission, sifting, electromagnets and optical inspection does not remove the tiniest of impurities. Small metallic particles are the most difficult to identify and remove. Non-ferrous metals (stainless steel, nickle, copper, aluminum, magnesium, maganese) cannot be removed with magnets. These very contaminates can be the very cause of cracking in finished tiles.
It is possible for tile manufacturers to chemically counteract the negative effects of some impurities, but not all - especially metals.
Metal particles are referred to as "stones." Over time, these stones change in structure. These changes cause internal stresses within the tiles. Eventually the stresses grow to the point where the glass cracks. Microscopic in nature, they are virtually invisible to the naked eye and beyond the ability (or manufacturer's desire) to be detected.
Refractory brick commonly errodes from the walls of the kiln, and becomes a contaminate within the molten glass. These are also called stones. Future thermal changes to the tiles will cause cracking, due to the differential expansion of materials.
Recycled Glass - Warm Fuzzies and Headaches
Using recycled glass as a component of glass tile production lowers raw material costs and provides consumers warm fuzzies.
The probability of contaminates is too high and potential for failures too great, to justify the installation of recycled glass tile mosaics in a swimming pool.
There are many first quality glass tile mosaics on the market to select from, to even risk considering tiles utilizing recycled glass content.
Once tiles begin to crack, water will infiltrate and soften the thinset. Sharp shards of loose cracked pieces of tile in a pool or spa pose a threat to bathers.
The cost to remove glass tile, repair the substrate and membrane and reinstall new tile is double the cost of a new fresh installation.
Roll the dice or make a sure bet... the choice is yours.
Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool and Spa ©www.aquatictechnology.com
You may contact Paolo Benedetti at: firstname.lastname@example.org or at 408-776-8220