Mohs Hardness Explained

Mohs hardness is a scale used to measure how resistant a material is to scratching. In the tile industry, it helps indicate how easily the surface of a tile may be scratched by another material.

Although Mohs hardness is often included in technical specifications, it is frequently misunderstood. It does not measure a tile's strength, durability or resistance to breaking. Instead, it simply measures scratch resistance.

Understanding Mohs hardness can help you choose tiles that are suitable for the demands of your home or commercial project.

What Is the Mohs Hardness Scale?

The Mohs scale was developed in 1812 by the German mineralogist Friedrich Mohs. It ranks minerals according to their ability to scratch one another.

The scale runs from 1 to 10, with each mineral able to scratch those below it. The higher the number, the greater the material's resistance to scratching.

The Mohs Hardness Scale

Because the scale is comparative rather than linear, the difference between each number is not equal. For example, diamond is vastly harder than corundum, even though they are only one point apart on the scale.

How Is Mohs Hardness Used for Tiles?

Manufacturers may quote a Mohs hardness rating to indicate the scratch resistance of the tile surface.

Generally, higher Mohs ratings indicate better resistance to everyday scratching, while lower ratings may be more susceptible to scratches from abrasive materials.

Scratch resistance can be particularly important in:

• Hallways.
• Kitchens.
• Commercial entrances.
• Retail environments.
• Areas where grit or sand may be walked indoors.

Typical Mohs Ratings for Tiles

The exact rating varies between manufacturers and tile collections, but as a general guide:

• Decorative glazed ceramic wall tiles often have lower surface hardness.
• Glazed porcelain tiles typically offer good scratch resistance.
• Unglazed porcelain and through-body porcelain often have higher scratch resistance because of their dense composition.
• Natural stone varies considerably depending on the type of stone.

Always refer to the manufacturer's technical data for the specific product.

Why Does Scratch Resistance Matter?

Over time, tiny particles of sand and dirt carried on footwear can act like abrasives.

In heavily used areas, these particles may gradually scratch softer surfaces.

A tile with good scratch resistance is more likely to retain its appearance over many years, particularly in busy households or commercial buildings.

Mohs Hardness Is Not the Same as Strength

This is one of the most common misunderstandings.

Mohs hardness measures scratch resistance only.

It does not measure:

• Impact resistance.
• Breaking strength.
• Flexural strength.
• Load-bearing capacity.
• Slip resistance.

For example, a tile may have excellent scratch resistance but still crack if a heavy object is dropped onto it or if it is installed over an unsuitable substrate.

Mohs Hardness and PEI Ratings

Mohs hardness and PEI ratings are often confused, but they measure different properties.

• Mohs hardness measures how resistant the tile surface is to scratching.
• PEI ratings measure how well the glazed surface resists wear from foot traffic.

A glazed floor tile may have a high PEI rating while also having a different Mohs hardness than another tile.

Together, these ratings help describe different aspects of a tile's performance.

Common Misunderstandings

Why Should Homeowners Care?

Understanding Mohs hardness helps you choose tiles that are suitable for the level of use they will receive. For example:

• Busy hallways and entrances benefit from good scratch resistance.
• Kitchen floors are exposed to frequent foot traffic and grit.
• Utility rooms and commercial areas may require particularly durable surfaces.
• Decorative bathroom wall tiles are less likely to experience scratching than heavily used floors.

Considering scratch resistance alongside other technical properties can help ensure your tiles continue to look their best for many years.

Conclusion

Mohs hardness is a useful measure of a tile's resistance to scratching, helping homeowners and professionals choose products that are suitable for different environments. While it provides valuable information about surface durability, it should not be confused with overall strength or impact resistance.

When selecting tiles, Mohs hardness is best considered alongside other technical characteristics such as PEI rating, slip resistance, water absorption and the suitability of the tile for its intended application. Looking at the complete specification rather than a single figure will help you choose a tile that is both attractive and durable.