The primary difference between Swimming Pool Mosaic tile and wall or floor tile is there resistance to Freezing, amount of Water Absorption and resistance to Chemicals. Now unless you would like to dig through the ASTM standards for various applications of ceramic tile, just know that the major manufacturers of Swimming Pool Mosaics use porcelain type clay and a glass glaze to cover the surface of the tile.
Resistance to Freezing
The amount of water that is absorbed is important especially for outdoor use. As you know, when water freezes it expands. If your tile were to absorb too much water and it freezes, then your tile will crack…not good. The way tiles are tested, using the ASTM C1026 testing procedure, is to freeze the tile to negative 0.4 F and then quickly heat to 50 – 60 F. This procedure is repeated 15 times. This criteria is especially important if you are putting your mosaics in an area which may freeze, such as steps, swim out, pool seats, on waterfall features above the pool’s water surface, outdoor table tops, outdoor kitchen backsplashes or on the pool deck. In climates where the temperature drops below freezing for any period of time, the pool water will most likely freeze. As long as your mosaics are well below the freeze depth of your pool, they will be fine, but I still would put only mosaics that are specified as “Frost Proof”. Be sure you review the product’s specification to determine if it is described as “Frost Proof”. If you are seriously concerned about your mosaics freezing, then I would suggest getting ones that are specified as Frost Proof Porcelain.
Water absorption rates are determined by using the ASTM C373 testing procedure. Standard wall tiles will absorb about 7% water, while ceramic Swimming Pool Tiles absorb about 3%. Porcelain tiles absorb around 0.5%. Why the wide differences in absorption rates? Cost and application. Tiles that are used on a wall in your home do not see much in the way of water, if any at all. It makes sense to not use the more expensive clays which has lower absorption rates for an application that does not require low absorption rates. On the other hand, tiles that are going to be immersed in water 24 hours a day, 365 days per year, would require tiles made from materials that has the lowest absorption rate. Besides the low absorption rate of the clay used, to further improve the resistance to water absorption of Swimming Pool Tiles, the top surface of all mosaics are made vitreous by covering them with a glass glaze which has a color pigment in the glass. This colored glass glaze is what gives the Swimming Pool Mosaics their brilliant color which will last a life time. The sides and bottom of each mosaic piece are not glazed. This is done on purpose. Your mosaic is attached to the pool surface, gunite, using a material referred to as thinset. Both the mosaic bottom surface and the pool surface must be porous enough to absorb the thinset thereby making a strong bond between the two surfaces. During the application of the finish coat, every mosaic is covered with the finish coat material. This material will seep into the space between each mosaic piece thereby further bonding the mosaic to the pool’s surface. Done properly, your mosaic will then be completely sealed.
The Swimming Pool Mosaics that live in your swimming pool live in a very harsh environment…for them, not you. Besides the water, your pool contains chlorine, acid and a few other chemicals which help prevent algae and fungus from growing. If you think about it, every time your children or yourself are finished with swimming one of the first things you do is rinse off the chlorine and other chemicals so they will not remain on your body after drying. Unfortunately, the Swimming Pool Mosaics do not get that treatment, so the Swimming Pool Mosaics must be completely impervious to the pool’s chemicals. Tiles are tested using the ASTM C650 testing procedure. In this procedure, tiles are soaked in a test solution for 24 hours at 74 F. The tiles are then inspected to see if there is any visible damage. As with water absorption, the glass glaze on the top surface of the mosaic helps prevent damage to the mosaics caused by chemicals. To insure that your mosaics stay bright and beautiful for the life of your pool, it is important to make sure your pool’s chemistry is always “in balance”. Keeping your pool in balance will also help prevent the calcium in your pool’s finish from being absorbed into the water.
In this article I have given you a lot of technical information which you may find interesting, but the bottom line is that the major manufacturers of mosaics for swimming pools, such as Artistry in Mosaics and Custom Mosaics make their products specifically to be used in a swimming pool. Both manufacturers guarantee their products for the life of your pool. I can say, from my personal experience of having been working in this industry for the past 20+ years, that I have never had an experience where a mosaic was damaged by freezing or chemical abuse. Remember, when installed properly, the only surface exposed to the water is covered with a glass glaze, making it completely impervious. So go ahead and focus on your design concept and the mosaics that will work best in your pool.