Here are the most common reasons:
* You might cut yourself.
* The knife might cut the dishwasher’s plastic coating on the racks.
* The hot temperature might harm the handle, especially if it’s wooden.
* The dishwashing detergent might make a glob on the knife blade and cause it to pit.
* The knife might knock against other stuff in the dishwasher and get nicked.
Then the Don’t-Do-It people always say the thing about how very little time it takes to wash and put away a good knife, if you do it right after you use it. The Damsel will concede that point, but it has only small relevance in a household full of kids who don’t clean up after themselves. (The Damsel would like to point out that she’s talking about teenagers using these knives, not little kids. Don’t be hatin’.)
The thing the Damsel was looking for was solid evidence that dishwashing a good knife would damage the blade, or its ability to be sharpened/keep sharp. That’s the thing that matters to the Damsel. Some sources mentioned this but, really, it came up pretty rarely, and there was plenty of people voicing the opposite opinion…that they dishwash their knives all the time and can’t see any harm.
Rather, the opposing team said they felt their knives were getting extra sanitary by going through a dishwasher.
So. It seems there is no clear “cut” answer to the question. (The Damsel cracks herself up)
The Damsel would love to hear your opinion: Do you handwash your beauties, or live on the “edge” and put them in the dishwasher?