Why freezing damages tile
Freeze-thaw damage needs water inside the material. Water that soaks into a porous tile expands about 9 percent as it freezes, and over a winter of freezing and thawing that expansion cracks and spalls the tile. A material that takes in no water has nothing to expand.
The standards, in plain English
ASTM C373, water absorption. Tile that absorbs 0.5 percent of its weight or less is classed as impervious, the lowest category.
ASTM C1026, freeze-thaw. Saturated tile is frozen and thawed repeatedly, then inspected for cracking and spalling.
ASTM C484, thermal shock. Tile is moved between hot and cold to check that sudden temperature changes do not crack it.
ANSI A137.2. The American standard for glass tile.
How our glass tests
Our smalto absorbs 0.02 percent water under ASTM C373, well under the 0.5 percent limit for impervious tile, and showed no failure in thermal shock under ASTM C484. The full results are on our specification sheet.
Smalti is also solid glass. We do not hold separate lab figures for it, so the numbers above apply to smalto only.
Both are cast glass, made from molten glass. The Ceramic Tile Institute of America describes cast glass tile as having “high breaking strength, chemical and freeze-thaw resistance” and being “impervious,” with a long record in “exterior applications, pools and domes.” (CTIOA Glass Tile Report, 2008)
Where cold-climate mosaics fail
CTIOA’s pool committee singles out tile above the waterline — “raised bond beams, feature walls and infinity edge spillways” — as the areas exposed to “extreme temperature variations, freeze/thaw conditions, or daily wet and dry cycles.” Raised spa faces and fountain walls are in this group. The failures come from the installation, not the glass:
Substrate and waterproofing. Water that gets behind the tile freezes there and pushes it off.
Movement joints. Structural joints must continue through the tile work, as ANSI A108.01 and TCNA EJ171 require.
Setting materials. Adhesive and grout must be rated for exterior and submerged use.
Installation temperature. Mortars and grouts installed in the cold do not cure properly.
Setting materials for glass outdoors
The installer chooses the setting materials and follows the manufacturer’s instructions. One system suited to glass mosaic outdoors:
Litokol Litoelastic EVO — a two-component reactive adhesive, class R2T under ISO 13007, rated for exteriors, pools, fountains and spas, in service from -40°F to 212°F. Its white color keeps glass colors true.
Litokol Starlike EVO — a two-component epoxy grout to ANSI A118.3, rated for pools, spas and tile exposed to extreme temperature changes, in service from -4°F to 212°F.
Both must be applied between 50°F and about 86°F, so in cold climates plan installation outside the winter months. CTIOA notes that epoxy grout suits small glass mosaics rather than large glass tiles, which fits mosaic-size glass.
What we supply
We fabricate; setting is a separate trade. Custom work arrives paper-faced in numbered sections, which lets the mortar reach the full back of every piece. When you send dimensions, tell us where the mosaic is going and whether it is exterior or submerged.
More on outdoor work: Can smalti be used for exterior mosaics? Specifying for a client? See the designers and architects page.
Begin your commission
Send the details of your project, or call (323) 389-5347. Studio hours are Monday to Friday, 9am to 5pm, and Saturday, 9am to 1pm, Pacific.