When it comes to determining material “scratch-ability,” experts often reference something called the Mohs scale (see the infographic in the middle of this article).
While glass is a relatively hard material, it’s actually only about middle-of-the-road on the Mohs hardness scale. Minerals like quartz, hardened steel, diamond, ceramics, and carbide-tipped tools have a higher Mohs ranking. In other words, they are molecularly “harder” than glass and able to scratch a glass surface.
What Is Glass? And What Is It Made Of?
It might surprise you to know that any material that is a “transparent amorphous solid” can be called a glass. Contrary to popular belief, glass is NOT a liquid. It also doesn’t have a fixed crystal structure like quartz, rubies, or even metals do.
Glass is basically silica sand (an extremely pure sand) that has been melted and allowed to cool. As it cools down, instead of forming crystals like most materials do, it hardens while keeping its liquid-like atomic structure frozen in place.
That’s what it means to be an amorphous solid.
Glass is solid, but its atoms are arranged randomly like a liquid, rather than in neat, organized patterns you find in crystals.
What Gets Added to Sand to Make Glass?
While sand is the star of the show, glassmakers often add other ingredients to make it more useful:
- Soda ash (sodium carbonate): Lowers the melting temperature so it’s easier to work with
- Limestone: Makes the glass more durable and weather-resistant
- Boron: Creates stronger glass that can handle temperature changes (like Pyrex cookware)
- Lead oxide: Makes crystal glass that’s extra clear and sparkly
- Iron oxide: Can tint glass green (which is why some bottles look greenish)
Different Types of Glass
About 90% of all glass is “soda-lime glass.” This includes your basic windows, bottles, and drinking glasses. But there are a few specialty types:
- Tempered glass: Heated and rapidly cooled to make it stronger (e.g. car windows, shower doors)
- Borosilicate glass: Contains boron for heat resistance (e.g. laboratory equipment, some cookware)
- Laminated glass: Multiple layers with plastic in between (e.g. car windshields)
What Materials Can Scratch Glass?
To scratch glass, a material must have a Mohs hardness greater than 5.5 (the level of glass). You’ll need something harder than copper, made of steel or titanium, and a little bit of a sharp edge. If an item is technically “harder” than glass but has a smooth surface, it’s less likely to leave a scratch (but it’s not impossible).
On the flip side, if a material has a Mohs hardness level lower than glass but is especially sharp or abrasive, it can still scratch glass with enough force.
Common materials that scratch glass include:
- Quartz (Mohs 7): Often present in sand and dust.
- Topaz (Mohs 8) and Rubies (Mohs 9): Generally only used for jewelry and special adornments.
- Corundum (Mohs 9): Common in jewelry, nail files, sandpaper, & whetstones.
- Diamond (Mohs 10): Used specifically to cut glass.
- Hardened Steel (Mohs 6-8): Present in screwdrivers, knives, keys, or razors,
- Ceramics (Mohs 5-9): Used in dishes, tiles, toilets, sinks, & decorations.
- Tungsten Carbide (Mohs 9): Leveraged for high-power carbide-tipped tools.
- Granite Dust (Mohs 6-7): Side effect of granite construction & general wear and tear of granite features.
- Silicon Carbide Dust (Mohs 9.5): Created when using certain abrasive tools for grinding, polishing, & cutting.
- Aluminum Oxide (Mohs 9): Often used in abrasives.
Here’s a thinker for you…
If glass is made of quartz sand (a.k.a. silicon dioxide), how is it that quartz (at Mohs 7) can scratch glass? And why is glass only at a 5.5 on the Mohs scale?
It all comes down to the molecular structure.
Both materials are formed with the same “building blocks.” However, while quartz is arranged in a highly ordered, repeating, three-dimensional lattice structure (i.e. it is crystalline), glass molecules are a bit more haphazard, lacking that uniform, repeating pattern that gives quartz its hardness.
Common Questions About Glass “Scratch-ability”
What makes glass susceptible to scratches?
Glass has an amorphous (disordered) atomic structure, lacking the strong, repeating bonds found in crystalline materials. This, combined with additives used in manufacturing, makes it inherently less hard and more vulnerable to scratches than harder substances.
Can all types of glass be scratched?
Yes, all types of glass can be scratched, but their scratch resistance varies significantly. Regular annealed glass is easily scratched, while chemically strengthened glasses (like Gorilla Glass) and especially sapphire glass offer much higher resistance.
What are the most common culprits of glass scratches?
While any material with a Mohs hardness greater than glass (typically 5.5-6.5) can scratch it, the most common culprits are sand and dirt (containing quartz), various ceramics, and harder metals.
How can I prevent scratches on glass?
Always clean glass surfaces thoroughly with soft, clean microfiber cloths to remove abrasive particles. Avoid dry wiping or harsh chemical cleaners. Use protective covers (like placemats or coasters on glass-topped furniture), and be mindful of direct contact with harsh materials.
Read More: Protecting Your Glass Surfaces: Scratch-Prevention Tips for Homeowners
Can I remove a scratch from a glass surface?
In some cases, very minor or hairline scratches can be polished out using specialized compounds and tools. Deep scratches are generally permanent (and may even develop into cracks). At this point, they cannot be effectively removed without causing significant optical distortion or further damage to the glass.
Is “scratch-proof” glass a real thing?
No, “scratch-proof” glass is a misnomer. While some advanced glasses and coatings offer significantly higher scratch resistance, no glass is truly immune to all forms of scratching, especially from extremely hard materials like diamond.
How to Deal With Scratched Glass
DIY solutions for scratched glass (like toothpaste, baking soda, or steel wool) rarely make things better. If you attempt to remove a scratch without the proper tools and expertise, you’re more likely to distort the glass or use a harmful treatment.
This will undoubtedly make it worse.
Instead, let a glass replacement and repair professional handle it. When you call Atlantic Glass, we’ll send over a technician to conduct an initial scratch assessment. After our assessment, we’ll replace (or possibly repair) the impacted glass panel(s).
Want to upgrade your glass to increase its scratch resistance? Ask one of our technicians about possible protective coatings or “scratch-resistant” glass types.
Get in touch with us today to see how Atlantic Glass can excel for you!
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