Ceramic knives have some particular benefits over steel knives. They are lightweight, stay sharper for long and don’t bruise soft fruit and vegetables.
But we all know, with great cooking comes a great (but not very fun) responsibility, cleaning.
For this task, the dishwasher can often be our savior, removing the need for endless scrubbing of utensils and plates in an overfilled kitchen sink.
But how about ceramic knives, is it safe to clean a ceramic knife in the dishwasher? Or is there a better alternative?
Ceramic knives are not dishwasher safe as they are brittle and can easily chip and snap. Ceramic knives will not rust but the motion of the dishwasher can damage the blade because ceramic knife blades are brittle and can chip easily if knocked against other hard objects.
Can you wash ceramic knives in a dishwasher
Whilst ceramic knives are ‘technically’ dishwasher safe because the moisture and heat itself won’t actually harm them, ceramic is so brittle that the movement within a dishwasher can easily cause the blade to chip.
It’s the action of other items within the dishwasher banging against the ceramic knife that can cause it to chip.
So whilst a ceramic knife would probably be ok if it was washed in a dishwasher on its own, without anything it can be rattled against, in reality, this isn’t practical and so it’s best not to use a dishwasher at all for ceramic knives.
It’s this clash with reality that leads to ceramic knives often been marketed as ‘dishwasher safe’. Technically they are, but in the real world putting ceramic knives in a dishwasher will eventually lead to damage due to their brittle nature.
| Blade Material | Cutting edge | Brittle / Flexible | Dishwasher Safe |
| Steel | Softer | Flexible | Sometimes |
| Ceramic | Harder | Brittle | Never |
Ceramic knives are sold as being extremely hard. On the Mohs scale of mineral hardness, hardened steel is between 7.5 and 8, ceramic knives (Zirconia) are rated at a higher 8.5, with diamond being at 10.
This hardness means that they retain a sharp cutting edge far longer than a steel knife.
However; ceramic knives are also very brittle, unlike steel knives which have a lot of flexibility.
Therefore; the inevitable knocks and bumps your knife will receive in the dishwasher will eventually cause damage, most likely in the form of chips on the knife blade.
There is also a potential second issue related to the hand of your knife.
Wooden handles are likely to warp and distort when repeatedly washed in a dishwasher and therefore they are an absolute no go, regardless of what material the blade is made from. Plastic handles, however, should be fine.
How to wash cermaic knives in a dishwasher
Ok, I get it, since you’re reading this article you may, for whatever reason, have no other choice.
If you are insistent on washing your ceramic knife in the dishwasher then take these steps to reduce the likelihood of damage.
Ensure that the knife is placed on the second shelf; preferably in a knife draw if your dishwasher has one, but more importantly do no place it anywhere near any other items which could knock into it during the wash.
How to to clean a ceramic knife
You really shouldn’t use a dishwasher to clean your ceramic knife. And with the use of a ceramic knife limited to soft fruit and vegetables it should actually be quite easy to clean anyway.
I would also advise that you don’t wash a ceramic knife in a kitchen sink where it could clatter against other utensils, instead a ceramic knife should be washed by hand.
I would recommend that you clean your ceramic knife after each and every use, simply rinse it under warm water and wipe it down with a soapy cloth or sponge.
That should be enough to keep it clean and well maintained for a long time to come.
Also, remember to store your ceramic knives safely when they’re not being used. By safely I mean protecting the blade from being chipped, so don’t just throw it in your knife drawer, if you have a sleeve for the knife use that, or put it in a knife rack, otherwise, your ceramic knives are likely to get little chips all along the blade.
What are ceramic knives
Ceramic knives are an alternative to steel knives because they are harder. This means that the knife-edge should stay sharper for longer if the knife is used for the right purposes and maintained in the right way.
Ceramic is strong but it’s very brittle, it may even snap if you drop the knife on the floor.
Therefore it is a great tool for thinly slicing soft fruit and vegetables but it should be used for any tasks involving harder bits, such as meat with bones, or tasks that need flexibility in the blade, such as carving or de-skinning.
They are also completely rust-resistant, so unlike a normal steel knife which needs to be kept dry, you could leave a wet ceramic knife for weeks and it would have no effect on it al all.
Since ceramic knives are none-rust then they should be perfect for putting in the dishwasher right? Well, maybe not, let’s discuss whether ceramic knives are dishwasher safe.
Fixing a damaged ceramic knife is tricky
It’s worth being careful when cleaning your ceramic knives because they can chip so easily. When they are sharp they can be a great tool but once you start getting a chipped edge it can be difficult to get a good sharp edge back on the blade.
Ceramic is such a hard material that you can only really sharpen it using a diamond-encrusted sharpening tool.
Just to prove that point, here’s quite a useful video of someone trying to restore a ceramic knife blade after it’s become blunt and damaged.
You can see just how much time needs to be taken to restore the edge, and even then it isn’t as sharp as it starts out. So be careful when cleaning your ceramic knife… and try not to use the dishwasher!
It is possible though. You can restore even very chipped, blunt and damaged cermaic blades back to their sharpest edge.
All you need are the correct tools and the right technique.
I’ve written a whole article about how to sharpen a ceramic knife here, so if your knife has been damaged in the dishwasher you should read that guide if you want some advice on how you can fix it.
