Guest Blog: Tile Tech Notes
April 14, 2010
The Fine Print
When you go to the showroom to pick out your new tile, the salesperson hands you a glossy brochure and shows you how this tile looks great with that doodad. You give the brochure a cursory glance and then stick it in your purse or pocket. WAIT! Skip to the end of that brochure and look at the fine print, because there are some important technical considerations to picking out a tile.
The Tile Council of North America does a good job of publishing and maintaining the American National Standard Specifications for Ceramic Tile. Collectively, these are known as ANSI 137.1, and the most current version as of this writing is from 2008. The specs themselves are 37 pages of fairly dense type and refer to many other documents, so I can’t give you a complete overview in this column, but I will hit on some of the specifications that manufacturers tend to list and why they matter. If you deal with tile regularly and haven’t looked through the specifications, I encourage you to do so.
Why do we need specifications in the first place? Mostly, because tile isn’t perfect. It varies in size, color, flatness, and sometimes has spots or chips or other imperfections. It also varies in the way it’s made. Glossy tile is more slippery, and rough tile is better for high traffic areas. Quarry tile isn’t glazed at all, mosaic tile is less than 3 in. on a side, and trim tile has its own unique shapes and sizes. Specifications help manufacturers, distributors, and end users know what is acceptable and expected.
First up: Aesthetic Classes, which is a fancy name for shade variation. Once upon a time, tile was all white (or that ugly pink color that was in the bathroom of your first house), and they were all supposed to look the same. The newest products on the market, however, are designed to look very natural and have a high level of variation. So how do consumers know if the variation they are seeing is on purpose or on accident? The answer is a table in the specs that ranges from V0 (no variation expected) to V4 (substantial variation expected). We manufacturers usually list our products using these V numbers so consumers know what to expect when they open up the carton.
Next comes the Visible Abrasion Classification, which details how prone the tile is to scratching. (Please note, this only applies to glazed tile.) This table ranges from 0 (don’t use this on floors) to V (you can roll a tank over this). Visible abrasion is determined by intentionally scrubbing the tile with very abrasive sand and seeing how long it takes before any obvious scratching can be seen. The longer the tile goes without scratching, the higher the classification.
Water Absorption is usually listed as well. When tile is fired, a certain amount of microscopic holes (pores) are left. If a tile is very porous, it will absorb a lot of water. This is important because, in an environment where the tile can be exposed to below-freezing temperatures, the water in the pores can expand and break the tile apart. By definition, porcelain tile has an absorption of < 0.5%. If the tile is “Certified Porcelain” (and it should be!), an independent lab has verified that the tile reaches this extremely low threshold. A Vitreous Tile ranges from 0.5 to 3.0% absorption and is generally considered safe to install outdoors. Semi-Vitreous tile absorbs from 3.0 to 7.0%, and Non-Vitreous tile absorbs from 7.0% on up. These types of tile should only be used indoors.
The last characteristic we’ll look at this month is Breaking Strength. This one is pretty straightforward-the manufacturer breaks 10 tiles and then lists the average amount of force it took to break them. This is important because it gives a rough idea of how well the tile will stand up to cracking and breaking. ANSI does have some minimum requirements: 125 lbs for a wall tile and 250 lbs for a porcelain floor tile, for instance.
One last note for now, specifications continue to evolve to meet the ever-changing world of tile. As tile gets larger, graphics get more complex and installations get more demanding, it is important for the industry to keep up to date. Committees meet regularly to make sure the specifications reflect reality. It’s always important to read the fine print!