Aquatic Technology Pool & Spa, "Creating Water as Art."™

Aquatic Technology Pool & Spa, "Creating Water as Art."™
Pools as an art form - the way it should be!

Thursday, April 24, 2014

Swimming Pool Glass Tile Mosaic Cracking - Tile Edge Quality

Poor Edge Tolerances

There are many reasons why glass tiles crack.  The most common is damage to the tile - a chip, scratch or impact.  These traumatic events occur during the manufacturing, handling, shipping or installation process.

Manufacturing Processes

Glass tiles are made into small squares by a number of various processes.  Cast or pressed, individually cut or snapped are the three most widely used methods.

Cast Tiles
Cast tiles are created when molten glass is poured into molds, individually forming each tile.  The process may be inverted, when a cookie cutter style press stamps out individual and distinct tiles.

Cut Tiles
Cut tiles are formed by cutting the tiles from a larger sheet of glass.  The tiles are usually then re-fired in a kiln to relieve stresses imparted during the cutting process.

Snapped Tiles
Snapped tiles are a more rudimentary method of forming tiles.  These are made by one of two processes: 
  • a cookie cutter style mold presses the tile shapes into molten glass.  The cutter does not separate the tiles into individual pieces, leaving them connected by a thin layer of glass.
  • molten glass is placed onto a mold tray and allowed to cover the mold.  It is then pressed or allowed to fill the cavities.  The tiles are connected by the layer of glass that remained across the dividers.
After annealing, they are later "snapped" apart, creating the separate pieces.  The process of snapping imparts chips and stress along the edges of the tiles.  Unless the tiles are re-fired in the kiln, these stressed tiles are handed off to the consumer.

Hard to Detect

These chips and stresses are hard to detect.  Since the tiles are usually mounted on an opaque paper, inspections are difficult for the end user, if not impossible.

Resulting Cracks

The stress that concentrates around these imperfections from thermal expansion will cause the tiles to crack.  Because not every tile has these imperceivable flaws, the cracking will occur randomly and the manufacturer will blame the installation practices.

Paolo Benedetti - Aquatic Artist "Creating water as art."™ 
Aquatic Technology Pool and Spa © 
You may contact Paolo Benedetti at: or at 408-776-8220

Saturday, April 19, 2014

Random Cracking Glass Tile Mosaics Swimming Pool

Most of the time, cracking in swimming pool glass tile mosaics can be explained by poor installation practices or shoddy workmanship.  Other times the cracking occurs without rhyme or reason in random tiles.
Random Cracking

Random cracking of glass tile mosaics is rarely the fault of the installer.  It is usually the symptom of inherent stresses within the glass tiles.
(Click on an image to enlarge it)
Random cracks in Oceanside Glass Tile Mosaics

But, without a "before and after" inspection of those same exact cracked tiles, there is no way to say with absolute certainty that the glass is to blame.  So it will become a case of finger pointing and blaming each other.

(Click on an image to enlarge it)
Random cracks in Oceanside Glass Tile Mosaics
Pre-Existing Stresses

A consumer or installer cannot be certain that any individual piece of glass tile does not possess a preexisting stress or flaw from the manufacturing process.

The only way to be absolutely sure, is to inspect each tile prior to installation... Time consuming and costly for sure.

Failure to Inspect
I do not know of any manufacturers of glass tile mosaics that perform a visual inspection of every single glass tile, prior to shipment.  Again, it would be too costly and time consuming.  

I'm sure that there are computerized optical inspection systems that could be employed, but after all it is "only glass tile."  The cost simply does not outweigh their liability for a few cracked glass tiles.

Protecting Yourself

The best way to protect yourself prior to an after installing glass tile mosaics, is to closely follow the installation instructions.

Unmounted sheets from each lot, color and pattern should be stored in a safe, cool & dry location.  Should there ever be a suspected failure, these samples can be tested at a materials testing laboratory for thermal shock resistance and inspected for preexisting stresses.

Paolo Benedetti - Aquatic Artist 
"Creating water as art."™ 
Aquatic Technology Pool and Spa © 
You may contact Paolo Benedetti at: or at 408-776-8220