Why are the Shadows on my Porcelain Tile

By Frederick M. Hueston, StoneForensics.com

 Over the past few months, I have been receiving calls about shadows that are on several porcelain tile installations. I looked at several of them and they were all installed within industry standards. So why are the edges of the tile appearing darker than the rest of the tile. Some have described it as shadowing. The following is a description of this condition and some possible causes.

In scientific terms this shadowing is known as Optical Hazing.

Optical hazing is a discoloration that appears on polished porcelain tiles.

Unless light is shone on the tiles from an angle rather than directly, these flaws are normally undetectable.

What can Cause Optical Hazing?

Imperfections caused by the tile manufacturing process.

The materials that are used in the manufacture of porcelain tiles.

The location or region where the tiles are made. China is particularly well-known for producing optically hazy tiles.

Raw materials or manufacturing of poor quality.

Stains or discoloration caused by the polishing process.

Water staining can leave marks on the tiles.

Uneven tile, known as lippage. The higher tile can cast a shadow on the adjacent tile.

One of the most common causes is nano sealers that are placed on the tile at the factory.

Hazing can appear in a variety of ways, including cloudy imperfections, shadows, and even veins running through the tiles.

Despite the fact that this is a widespread issue, there are ways to treat optical hazing and mitigate its effects.

Not all tile imperfections are caused by optical hazing, and it is critical to correctly diagnose the problem before determining the best solution.

A white haze on the surface, for example, could be caused by grouting affecting the tiles during installation. This is known as grout haze, and it is treated differently than optical haze.

If there is any doubt about whether the imperfections are caused by optical hazing, it is best to consult with experts.

Repolishing porcelain tiles can frequently remove optical hazing.

However, not all polishing processes are effective on all types of hazing, particularly hazing with veins running through the tiles. To completely remove the appearance of optical hazing, stone restoration techniques may be required before the tiles can be re-polished.

To determine if the tiles are defective, it is best to have an expert perform and inspection. Optical hazing maybe just a matter of improper lighting and simply changing the lighting type may solve the problem.