Do glass cutting boards blunt knives?

Do you use a glass cutting board, and if so are you worried about it blunting your knife or otherwise affecting your food?

Let’s find out the truth about glass cutting boards. Post your answers below and enter our competition

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I think that glass cutting boards do blunt knives, since the blade will hit something solid like glass. Unlike wooden or plastic cutting boards, they have give for the blades which in turn doesn’t blunt them so quickly.,


Good question. I only use wooden or the nylon cutting boards. I don’t cut on any hard surfaces, including glass, stainless steel, etc.


Yes they do. Hell has a special place for those who mistreat their tools.


Yes. In a very general sense, accepting there is a variation in the quality and hardness of both glass and knives, they share a similar ‘hardness’ value on various hardness scales, Mohs as one example (testing hardness of glass is problematic as it is not typically receptive to testing procedures without exhibiting its brittle consequences). It stands to reason the harder the cutting board the quicker the knife will become dull. It also seems fairly evident that the harder a knife is, the more likely it is to actually cut the board. In the case of timber probably a minimal concern, plastic a little less desirable - glass fragments though I’m eager to avoid. The glass could be tempered of course, but it’s still an arms race of which is harder …

I use timber. I’m not even that concerned about ‘food safety’ which seems to be a selling point of the glass and other less porous cutting boards - a good wash in hot soapy water, rinse, dry properly … maybe I’ve been lucky …


It depends on which one is harder, more compressive/flexible and is more abrasive. I expect that glass and hardened stainless steel (like that used in stainless steel blades have similar hardness,…maybe glass slightly harder with less flexibility and ability to compress/change shape) while stainless steel would be more abrasive than (plate) glass.

When moving the stainless steel across a glass cutting board (slicing action) and as stainless steel is potentially more abrasive (fine grooves caused by the sharpening processes), the stainless in theory should scratch the glass surface. If the glass is very smooth and little downward force is placed on the knife, then it is possible that the knife remains unimpacted by the glass cutting board. (If the glass was abrasive such in a textured glass board, it could wear off the cutting edge).

Now, then chopping (the blade coming down vertically against the surface of the glass at an angle near to 90 degrees), the stainless steel blade is likely to get dull, The force on the knife edge would be enormous (could be many tonnes per square centimetre) and the sharp blade would compress and potential deform at the very tip (sharp edge).

So I think that chopping is a no-no on a glass board (as high forces could also shatter the board), while slicing is okay and unlikely to dull the knife if only horizontal forces are applied, without much downward force.

I also think that it is near impossible not to place downward force when cutting, so invariably the knife will dull quicker over time compared to using softer boards such as wood or poly (a wooden or poly board which would deform instead of the knife during chopping or slicing).


On the Mohs hardness scale Steel is around 4.5 to 5.5 depending on carbon and other components. Glass is generally 5.5 it can also be harder or softer depending on additives. Most knife blades are softer than glass ie less than 5.5 and the action of cutting would cause the blade to be blunted. Stainless Steel tends to be a softer metal than Carbon Steel as it usually has softer non ferrous metals added to produce the “stainless quality”. Of course these are generalisations and there are obviously variations but in general a glass board would have a more pronounced blunting effect on a knife than if a softer cutting surface was used eg Plastic, or wood.


I also agree that wooden boards don’t harbour those germs that health boffins are so concerned about if its washed properly e.g. scrubbed with detergent and warm-hot water. Think I rather eat bits of timber than plastic. Normally if using raw chicken, after cleaning my way, I then pour a couple of capfuls of white vinegar. Thankfully no problems so far.


This may be of interest…


Thanks for the excellent answers everyone. I’ve selected @phb comment as the solution but if needed we can always update the thread again. We also appreciate the comments on the pros and cons of food safety concerns and the possibility of fragments from each board - it definitely ads value to include these other considerations.


Great article!

So my iron bark hardwood cutting board is healthier than my pine softwood cutting board.
Put my plastic cutting boards in the dishwasher (if they’ll fit); and throw them away when they have too many deep grooves.

A comment about steel knives - manufacturers have to compromise on the hardness of the steel to make the metal soft enough to sharpen yet hard enough to hold its edge for a reasonable time. Very hard steel knives are not useful long term as they are so hard to sharpen.


It’s a case of horses for courses. I don’t agree about the hard steel knives.

The mass produced knives made for the general consumer have softer steel so they are easy to sharpen. But, they are equally easy to blunt. Sadly, too many people don’t sharpen their knives so they become blunt, unpredictable, and therefore hazardous to use.

Quality ‘Professional’ knives use harder to hard steel, assuming that generally the people who buy them should know how to keep their knives sharp and in good condition.


On a slightly different note, whilst watching Justine Scofield on her Everyday Gourmet TV cooking show, I was interested to learn that you should never use the cutting edge of your knife to move the chopped food off the cutting board as it will make it blunt, but to use the back of the blade instead.

As for sharpening, we have a Baccarat Santoku cook’s knife and a small utility knife that I use on most days, along with an old Wusthop Trident knife sharpener.

The knife sharpener is made of wood with a hand hole at one end and a pair of ceramic sharpening wheels at the other end.

I sharpen the knives before using them, and when I have finished, they will slice through a supermarket receipt or any other thin piece of paper, which I use to test their sharpness.


Softer steels are actually harder to sharpen than hard carbon steel but there has to be a compromise between hardness, toughness, flexibility and rust resistance. If a knife is too hard/brittle, the edge can chip or the blade may snap instead of flexing. Also, creating a steel more resistant to rust lessens its ability to be quench hardened and tempered effectively.

This makes a lot of sense when you think about it. Steel hardness vs glass hardness logic aside, it is the burrs on the cutting edge that come into play here. A soft leather strop is able to manipulate these relatively hard burrs, either by aligning them or breaking them off to achieve a more effective cutting edge. Conversely, swiping a knife sideways on even a soft wooden board could bend these burrs out of alignment, effectively blunting it.

After using glass, plastic, and wooden cutting boards, wooden is my preferred now. I did find glass hard on knives and the sound of a knife clashing against glass went down my spine. The plastic boards stained easily and in some cases absorbed smells I couldn’t get rid of.


[quote=“V8Snail, post:14, topic:15293”]
Softer steels are actually harder to sharpen than hard carbon steel but there has to be a compromise between hardness, toughness, flexibility and rust resistance.
[/quote] Totally agree.

My sharpener of choice is the Furi three step system.
Because it is designed to get optimum angle every time (for their steel’s sheer strength, hardness-softness), I find it easy to use; and does not require any guesswork.