Why does washing knives in the dishwasher dull them?
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I don’t like washing my knives in the dishwasher because I’m worried about them rusting quickly. I wash and dry mine by hand
Dishwasher detergents are very abrasive, and meant to be used primarily on ceramics, heavy glassware and things that won’t easily stratch.
On a side note, I notice that if I put my normal table knives in the dishwasher they almost become slippy when spreading butter or anything. Is this a thing or is my dishwasher weird?
Because a knife is literally a sharp edge, dulling it in any way is bad. Ruining the temper with high heat, leaving it in soap. Etc dishwasher is the worst
I’m late to the party but here’s my answer. I was told that the high heat of a dishwasher would, over time, ruin the temper of the steel. I haven’t found any evidence that this is true. Tempering steel happens at a much higher temperature than dishwashers could possibly reach, unless the knife fell directly onto the heating element during a dry cycle. Even though I know this is true, I still hand wash all my good knives.
Try crumbling up a ball of aluminum foil and throwing that in your dishwasher with your dinnerware and glasses. Chemical reaction brings the shine back to your dishes. It works by oxidation, and ion exchange…not a scientist, but it’s a process between the detergent and the aluminum. Just crumble a ball of aluminum, and drop it into an empty part of the silverware holder. Look this hack up, it can probably be explained better.
Rule of thumb: put all varieties of cheap knives in the dishwasher, then sharpen or replace them as needed.
Keep expensive knives out because:
1) The heat and corrosive chemicals in dishwasher detergent are hard on all surfaces, including handles.
2) The inevitable jostling the edge will take against hard surfaces, dulling it.
3) There is no perfect steel. All steel carries with it trade-offs in the form of corrosion resistance, ease of sharpening, edge retention and toughness. The more expensive the kitchen knife, the higher the likelihood that some corrosion resistance was given up in exchange for increases in the other categories. That means chemicals (and sometimes even leaving them to air dry) will impact the performance of a fine edge.
The cleaning chemicals and the speed of the water act like sand paper blasting over the fine surface of the blade edge and eventually begin to round it
Buy an expensive knife. See how many paperback magazines you can cut through before the brand new knife is dull. It’s called friction
I read some comments, but I think I didnt see this one yet:
For most stainless steel knives the dishwasher is completely safe. But there can be a build up of all kinds of salts or even little “rust spots” (cannot really describe it in English sorry) that sort of clog up your blade. You can remove most of them with a sharpening steel.
Handles can be a bit of a problem but there are dishwasher safe kitchen knives for food industry out there (they are literally indestructable for household application). These also come with the benefit of anti-slippery handles and are also comparatively cheap whole being top quality.
To prevent dulling of the blade get a sharpening steel and use it every time before you use your knive.
If you are a sharp knive fetishist like me you have to thoroughly resharpen your everday knife every 6-12 months anyway, so even if the blade dulls a bit faster in the dishwasher it’s worth the time saved imo.
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