Optical Hazing in Polished Tiles

This effect is not a new phenomenon.  So what is Optical Hazing?  How does it present itself and what causes it?

 Firstly, it will present as a smoky, hazy, smudgy type of finish in the surface of polished porcelain tiles, it will only be visible when a direct light source reflects at a certain angle across the surface of the tile. 

It is caused by light.  If you could observe a ray of light approaching a mirror you would see it also bouncing or reflecting from the mirror.  Where and how it bounces or reflects is referred to as the “behaviour of lights as it reflects” and is known as the “law of reflection”.

Reflection off a smooth surface such as a mirror is known as specula reflection.

Reflection off a rough surface such as ceramic tiles is known as diffuse reflection.

​Many consumers have expectations that their polished porcelain floor is going to have a mirror like finish.  A polished porcelain tile is not a mirror. When the surface of a polished porcelain tile is examined under a microscope, small micro facets are found.  Light that strikes these micro facets reflects in a diffused manner giving a “Halo” or “Haze” effect.

The amount of haze visible depends on several factors:

• Number of light sources ie. a single source of light would limit the number of positions available to observe any haze.  The same surface when lit by a number of light sources will increase the amount of haze visible as there are more opportunities to see the reflected light.
• Bulk sunlight shining through large windows and doors will increase the amount of haze visible.
• The size of clay particles and other ingredients of the tile can also have an effect on the amount of haze visible.

 
​Optical Haze on polished porcelain tiles is not related to cleaning or wax residue problems.  It is an inherent characteristic of the tiles, stemming mainly from the mineral content and manufacture of the polished porcelain tile.  It has no effect on the technical performance of the tile.

Optical Hazing is not a defect

To date it is not something the Australian Standards require to be tested.  It is generally only visible in low angles of reflected light and is primarily an aesthetic issue.

It is worth restating: “Polished porcelain tiles are not mirrors and such an expectation should not be created during the selling process.   It is paramount that the consultants advise the end user of Optical Haze Characteristics that may occur.”

Credit: Australian Tile Council