Beverly Hills swimming pool designer Paolo Benedetti discusses the importance of using white thinset

Paolo Benedetti, an internationally renown Beverly Hills swimming pool designer, builder of infinity, vanishing, and disappearing edge pools discusses the importance of creating installation mock-ups and of using the correct materials when setting tile & stone.

Backing Color
Since most glass tiles are somewhat translucent, it is imperative that the surface behind the tiles be white. This means that waterproofing systems, thinsets, mortar beds, basically anything in contact with the reverse of the tiles.

Membranes
Most membranes are colors other than white. Most are of colors that owners do not want to see: blue, red, black, green. Since tiles can vary slightly in their thickness, it is important that there be a layer of something white on top of the membrane. This can be as simple as placing a skim coat of a white thinset on the membrane before installing the actual setting bed of thinset.

Installers usually tap the surface of the tiles to ensure complete embediment into the setting bed. The thicker tiles will embed deeper than the thinner tiles. This will displace more thinset than the thinner tiles... resulting in a thinner layer of thinset below the thicker tiles. A colored membrane may show through this thinner layer a little more than the thicker layer below the thinner tiles.

Thinset - Gray or White??
I just explained why white behind lighter colored glass tile is so important. So the answer should be obvious... WHITE THINSET under light colored tiles, GRAY under dark colored tiles.

Glass tiles come in all formats, opaque, translucent, clear, integral color, and colored back coatings or any combination of the above. Light colored tiles will provide a true color rendition when white thinset is used.

When setting clear tiles, you should always create some mock-up sample boards. I know there is an additional expense and related time delays, but a few days spent here will save you a lot of agony in the future (and the expense of tearing out tile & starting over). You might not be satisfied with the color rendition when a gray background is used.

Grouts
Grouts will also change the color of the tile. Since the grout is worked in between the tiles, it will impart a hue within the glass. A dark grout will darken the color of the tiles, while a lighter will brighten it.

However, using a white grout with dark colored tiles will make the surface look like a giant crossword puzzle. So it is best to select a grout color that is close in color to the tiles. This is most important for clear or opaque tiles, that will "read" the color of the grout.

Be sure to soak the grouted sample board underwater for a period of time prior to making your selection. After being underwater for sometime, the grout will absorb water. This saturation will darken the color of the grout. grout underwater will be darker, while the grout above water will be lighter. So - be sure to wait for the grout to absorb some water before making your choice in grout color!


Paolo Benedetti - Aquatic Artist"Creating water as art."™Aquatic Technology Pool & Spa©www.aquatictechnology.com

Glass Tile Fracture & Failure - Glass Tile Mosaics, Cement and Alkali Silica Reaction

Paolo (Paul) Benedetti founder of Aquatic Technology Pool and Spa, an internationally recognized aquatic and water feature designer and builder discusses the failure of glass mosaic tiles... simply due to the installer's failure to read and follow the installation directions. His vanishing edge, infinity edge, knife edge, and perimeter overflow pools grace some of the most sophisticated estates in the world.

Read the Instructions BEFORE you have problems...

Failing to precisely follow the installation instructions for glass mosaic tiles can result in a catastrophic failure of the tiles or specialty coatings. Most men have an aversion to reading instructions or taking advice. Let's face it, it's a guy thing... whether it be a road map (before we get lost) or the assembly instructions for that new kid's bicycle on Christmas morning (before we curse and swear Santa and the Elves for not bringing it fully assembled!).

The Manufacturer's include Directions for a reason...

I recently reviewed an installation where the glass tiles seemed to be disintegrating right before the owner's eyes. The grout in some areas of the installation was intact & beautiful. In other areas of the installation (and coincidentally around the failing tiles), the grout appeared to be forming a white gel like coating on the surface. I immediately knew what was happening, but now had to determine WHY. Perfectly good tile was being destroyed by a shoddy installation.


The tiles in the above pictures were not subject to saturation from the fountain, and therefore the ASR had not formed (yet). Click on the image to see a larger view.

In the above image, you can clearly see the white gelatinous material forming between the tiles... almost like a white slime. Click on the image to see a larger view.

Alkali Silica Reactivity (ASR)

Alkali Silica Reactivity (ASR) is nothing new. The phenomenon has been around for centuries. It is based in science & chemistry. To explain it in simple terms, when high alkali cements are exposed to silica (a basic element in glass), the cement will turn gelatinous.

This gelatinous material expands as it forms, causing the cement to crack. Certain colors of glass can actually accelerate this reaction. The finer the particles of glass within the cement, the more severe the reaction. This is a real concern where ground glass is added to cement as an aggregate (recycling) or for decorative reasons (sparkles in the glass).

The ancient Romans used to add pozzolans (volcanic ash) to their cements to help prevent this from occurring. I doubt that they knew why it worked, but it did. Today, there are chemicals & other additives that can be incorporated into the cement to prevent this from occurring. Lithium, metakaolin (produced from kaolin clay), and fly ash are all used in different applications to control and prevent ASR.

Where the wheels fell off...

The tile in this case was from a quality source... Sicis. I have used Sicis in the past & continue to use their materials. I have found them to be first rate, and I do not intend to insinuate that the product is inferior in any way. The problem here, is that the installer created a chemical reaction that could be created with ANY brand of glass tile.

As with any material, you have to follow the installation directions. The installation instructions from the material manufacturer ALWAYS takes president over any other published standard or guidelines. After all, the manufacturer knows best, as to what works with their products.

After talking to the property owner & their installer, I quickly realized that the installer had relied upon what I have previously referred to as a set of the "daddy-dids" standards. He installed the tile the way his "daddy dids it," "the way I always have." However, had he bothered to read the instructions from the tile manufacturer, he would have clearly seen a large warning in the instructions. He had added calcium to the leveling bed, in order to accelerate the hardening, and therefore allow him to set the tile quicker (after all time is money, right??).

The instructions clearly state to avoid using high alkali cements & products where the tiles will be exposed to high levels of humidity (moisture). In a fountain or swimming pool, do you think that the humidity level is high??? Like maybe 100% !!!??? His addition of calcium to the mortar and failure to install a waterproof membrane accelerated the demise of this project.

Click on the above document to open a larger version for review. Under the left column "Laying & Sealing" heading, the second paragraph clearly states "adhesives containing alkaline-earthy hydrates (e.g.,. calcium carbonate) should not be used..."

Hiring quality installers

This is another example of the old adage... "You get what you pay for." Just because someone is a tile installer, does not mean that he is a glass tile installer. Glass tile installations take a special set of skills & knowledge. The installers that I know & use, have been installing glass tiles for decades. They have a intimate knowledge of the various standards that they must adhere to (TCNA, ANSI 108.5, etc.).

The best installers know what questions to ask, create mock-ups for testing & for the client to approve, and most importantly - they read the directions from the tile manufacturer. They use the recommended setting materials, and even read the directions of those products.

Documentation is also important in glass tile installations. Keeping track of when certain areas were floated, set, & grouted ensures that the proper curing times were adhered to.

Tracking & recording the production lots of the various setting materials used, also allows for "reverse engineering" and a linear accountability in the even of any issues of this sort. And of course, tons of pictures. Digital images are free, so there is no excuse to not take thousands of them!

The only means to correct this failing installation, is to strip the entire job and start over. Where's the money savings now??

In this close up image, not only is the ASR gelatinous growth visible, but the additional calcium (lime) is bleeding out of the grout joints. Click on the image to see a larger view.

Hire quality designers, craftsmen and specifiers and you'll actually save yourself a lot of heart aches and money in the long run!

Paolo Benedetti - Aquatic Artist"Creating water as art."™Aquatic Technology Pool & Spa©www.aquatictechnology.com