The installer it telling you that it's normal or from airborne mold spores during installation. But you have doubts... and you are correct in your suspicions.
Source of Discolorations
Most discolorations are the result of installation errors. They can be from any of the following installation mistakes:
- using gray cements or setting materials
- not keeping the tiles shaded until the pool is filled
- not protecting the work from rain or irrigation water
- allowing the bond coat to skin over (poor bond, voids)
- too thin of a bondcoat
- excess water in the bondcoat
- incorrectly using the direct set (two step) installation method
- leaving trowel marks
- grouting too soon (not allowing the bondcoat to fully cure)
- filling the pool too soon after grouting
- fielding mixing setting materials (results in unknown sheer and compression strengths, density and permeability)
- not using a waterproof membrane
- too thin of a bondcoat (allowing the membrane to shadow through)
- allowing ground water to soak through the pool shell
Regardless of what the installation method your installer or the tile manufacturer recommends, there are acceptable industry standards.
Many foreign manufacturers are not aware that the tile industry in North America has performed significant testing and analysis if glass tile mosaic installation practices. They have established acceptable methods of installing glass tile mosaics that apply to EVERY INSTALLATION in North America. They are the GOSPEL for glass tile installations.
These practices are published under the ANSI A108.14, A108.15 and A108.16: Standards for the Installation of Glass Tile Mosaics. They also make direct reference to the quality and performance standards for the required mortar beds, waterproof membranes, bondcoats (thinsets) and grouts.
The field mixing of mortar beds and setting materials cannot guarantee that they meet the ANSI performance standards.
Paolo Benedetti, SWD Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management
Contact the author at:
email@example.com or 408-776-8220
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