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Talking about tiles: PEI and Mohs

PEI and Mohs

The technical specifications for tiles include reference to the Porcelain Enamel Institute (PEI) and Mohs ratings, but what are they and what do they reflect? Understanding these two measures can help determine the best choice of tiles for a particular application, particularly for commercial projects. 

What is the PEI rating? 

The PEI wear abrasion test is used to classify tiles according to the field of use, and the expected type of traffic and abuse the tile is likely to experience. It is a wear rating specifically for glazed ceramic tile surfaces.  

Mohs rating versus PEI rating 

While PEI measures the wear rating of a tile, the Mohs rating is used to identify a tile’s resistance to scratching. A tile sample is tested by pulling minerals with predetermined hardness ratings across the tile face. The mineral that succeeds in scratching the tile determines its rating. This test is commonly performed on glazed tiles, but it can also be used to determine how easily polished porcelains or other specially finished tiles will scratch. 

The higher the rating, the more scratch-resistant the tile. A rating of 7 or more is preferable as this is quartz, a primary raw material in ceramic tiles. 

Bright glossy glazes do not usually offer particularly good surface hardness (5 to 5,5), while matt products or products with surface crystallisation may reach and exceed a Mohs value of 7. Much like cars, lighter colours generally hide scratch marks better than darker colours. 

Knowing the PEI and Mohs ratings of a tile helps to determine the best fit-for-purpose choice for different areas within a project. 

 Full acknowledgement and thanks go to for the information in this article. 


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