Definition: The PEI rating is essentially a measurement of the surface glaze's resistance to abrasion. This measurement only applies to glazed tiles.

Importance: It's important to pay close attention to the PEI class when choosing a tile for a particular application.

PEI Classes:

Class 0 - Light duty walls only, never underfoot

Class 1 - Walls of all applications, never under foot

Class 2 - Walls and light duty floors such as residential bathrooms

Class 3 - Residential floors and walls

Class 4 -  Residential floors and walls, Medium traffic commercial

Class 5 -  Any area residential or commercial

Definition: The range of shade variation to expect on the tile. It ranges from no shade range detectable by the average eye (V0) to the potentially extremely varied color and tone of a (V4).

Importance: To recognize how much variation to expect on the tiles so that you don't get surprized and say either of the following:

• “That is not the tile that I picked!”
• “My newly tiled floor doesn’t look anything like the sample board.” 

V0 - Pieces of the same shade value are very uniform and smooth in texture. They can be measured for small color differences and are in compliance with color uniformity requirements.

V1 - Differences among pieces from the same production run are minimal.

V2 - You'll notice clearly distinguishable differences in texture and/or pattern within similar colors.

V3 - While the colors and/or texture present on a single piece of tile will be indicative of the colors and/or texture to be expected on the other tiles, the amount of colors and/or texture on each piece may vary significantly.

V4 -Random color and/or texture differ from tile to tile, so that one tile may have totally different colors and/or texture from that on other tiles. Thus, the final installation will be unique.

Definition: Ability of the tile to withstand temperatures below zero degrees celcius.

Importance: This is great for installing tile for outdoor use otherwise the tile might crack or easily wear out it's colour after a cold season.

Definition: One of the most important tests for identifying mineral specimens is the Mohs Hardness Test. This test compares the resistance of a mineral to being scratched by ten reference minerals known as the Mohs Hardness Scale. The test is useful because most specimens of a given mineral are very close to the same hardness. This makes hardness a reliable diagnostic property for most minerals.

Importance: If you are planning to put a tile in a high traffic area or an area that is pronote to abrasion, then it's important to consider the Mohs Hardness Scale of the tile in the selection process.

Mohs Hardness Scale:

Definition: Water absorption rates are a measurement of how much moisture a specific type of porcelain tile is likely to absorb on an ongoing basis. 

Importance: Some types of tiles may crack if the moisture penetration is too high.

The four different ratings for tile moisture absorption are:

• Non-vitreous (Low density) – Tile with water absorption of more than 7.0 percent
• Semi-vitreous (Medium density) – Tile with water absorption of more than 3.0 percent, but not more than 7.0 percent
• Vitreous (High Density) – Tile with water absorption of more than 0.5 percent, but not more than 3.0 percent
• Impervious (Extremely dense) – Tile with water absorption of 0.5 percent or less. This is where porcelain tile is generally categorized

Note: Porcelain tile is defined by ANSI A137.1 as an impervious tile with a water absorption of 0.5% or less as measured by the ASTM C373 test method.

Definition: People generally slip on wet surfaces or wet shoes, not clean dry surfaces. This  is a test that measures the amount of force required to keep an object in motion as it slides over a tile and reflects real life situations where a person might slip on wet tiles.

Importance: This is important to consider when selecting tiles if you are putting tiles in a location that is subject to traffic and exposed to water such as bathrooms or even front foyers.

North American Standard - DCOF (Dynamic Coefficient of Friction)

The measurements require that for level floor tiles, wet with water.

Interior Floors: Minimum slip resistance is 0.42 DCOF

Exterior floors: Minimum slip resistance is 0.60 DCOF

Other situations, such as slope, standing water, oil, grease, or other slippery substances, may require higher DCOF numbers.

The European (ISO) Standard - R rating (ramp test)

This test requires an operator who is protected by a fall restraint harness, and wearing standard footwear, walk backwards and forwards over a sample of a flooring material that has been evenly coated with oil. Beginning with the ramp in a horizontal position, they gradually increases the angle of inclination until the limit of safe walking is reached and the test person slips. The acceptance angle obtained is used to express the degree of slip resistance. The ratings scale goes low to high, R9 – R13.

Definition: Based on various characterists of the tile, some tiles are rated for walls and some are rated for both walls and floors.

Importance: This is great for knowing if a tile is suited for walls and not for floors.

Definition: The country in which the tile was manufactured in.

Importance: This is important becuase different countries set different standards for tile. For example, the tile industry in Italy has a high standards for tile produced (which is governed by Certifications that the tile must pass) than a country like China.