washing a knife in the dishwasher: screws up heat treat?

C

cognitivefun

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Oct 24, 2004
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Just wondered if washing a knife in the hot dishwasher messes with the heat treat.

How about washing a knife in extremely hot water in general?

Thanks!
 
No, I doubt that that dishwasher temperatures are hot enough to ruin a metal's heat treating.

-Bob
 
Water boils at 212F... as far as I know, you don't really get any effect at all (as far as heat treat goes) till you get upwards of 300F.

Which is to say, if it's still water, and not steam yet, it's never going to be hot enough to hurt.

Mike
 
A hot water heater generally is set at about 140-150 degrees. Probably 125 at the low end and 160 at the high end. Probably not hot enough to do anything, but I don't know that much about heat treating.
 
I don't think water can get hot enough to wreck a knife temper, unless you superheat steam.

The hottest dishwasher I have ever seen was one at a restaurant I worked at in high school, probably near boiling hot, but it did not wreck the knives.
 
I've read others that do it, and if I remember correctly, Sal from Spyderco mentioned that he uses the dishwasher. If it was going to hurt the knife, he wouldn't mention it to others...
 
There has been some good threads on this. Mainly, I have to admit that I sometimes run my knives through the dishwasher and get hammered on, oh well.

From what I've read, a stainless blade with a water impervious handle (nylon or something like that) won't be hurt by running it through the dishwasher. You do need to be careful about the edges hitting stuff, mine has a plastic "basket" with individual slots for knives. Also, someone mentioned that the dishwasher soaps are really quite strong; they etch my glasses eventually. I don't know much about how chemicals can affect the blade, but I thought it worth raising.

A carbon blade will rust and you will ruin certain handles. My steak knives have been through the washer 100s of times. The wooden handles do look like crap, but they were cheapies anyway and they haven't failed. The serrated blades have been sharpened maybe twice. They aren't great but do the job. I don't send any of my "good" knives through.
 
Hi All-

A dishwasher with all that steam is a harsh environment and it won't even do a better job of cleaning. Stick to washing high-quality folders by hand with a sponge and soap. You'll better reach the nooks and crannies and can properly dry and relubricate the knife afterwards.

~ Blue Jays ~
 
Just like to add: There's usually a heating element at the bottom of the dishwasher. It looks like something out of an electric broiler oven. If the knife manages to fall during the wash and land on the heating element, I imagine it could screw up the heat treat during the superheat dry cycle.

I'm not saying it's a good idea, but if I were to try it, I'd place the knife somewhere in the top rack--away from the heat source, and I'd try to make sure there's no way it could fall to the bottom of the machine. To me, the whole point of using the dishwasher is for the heat it can produce--so it's better able to sanitize the utensils. I don't like disabling the heat, makes me feel it's no more sanitized than hand washing them.
 
Blue Jays said:
Hi All-

A dishwasher with all that steam is a harsh environment and it won't even do a better job of cleaning. Stick to washing high-quality folders by hand with a sponge and soap. You'll better reach the nooks and crannies and can properly dry and relubricate the knife afterwards.

~ Blue Jays ~
Click to expand...

That's just the way I feel about it. If you care for your knife, treat it
with care. It gives 'bonding'.:thumbup:
 
No, the temperature is the dishwasher is far to low to get a tempering effect on the knife steel.

The only concern you have with washing knifes in a dishwasher is corrosion resistence. Hot water and chemicals can effect the blade, so be careful.

//Jay
 
The dishwasher detegent is really harsh, particularly when the water is hot. It will quickly damage the finish on wooden knife handles and cause them to crack eventually. Even plastic handles will often lose their gloss. Things rattle around during the wash cycle which can dull the blades. Some lower chrome/higher carbon stainless may corrode a little.

Sal at Spyderco selected the MBS-26 alloy for their kitchen knives and their handle material to better handle dishwasher use.
 
Hey, Rat Finkenstein, nice avatar. Günther is freakin' hilarious. Tuttifrutti summerlove... hahahahahahahahahaha

I don't put my knives in the dishwasher....
 
I have been washing knives in the dishwasher for over 20 years with no ill affects to the blades. Stabilized woods and Mikarta handles are not bothered by the heat and soaps. They do lose their shine, but putting them on the buffer for a few moments makes them shine like new. I wouldn't put any natural woods or bone handles in the dish machine though as these will definitely suffer.
 
Dishwasher detergent contains abrasive to help blast food off the dishes. That's why glassware gets those little scratches that make it look hazy after a while.
 
Dishwasher detergent does not contain abrasives, it does contain some strong basic detergents. They formulate it to go easy on glassware and dishes. They load it with some silicates to reduce glass etching. If they didn't do that your glasses would all be etched in a few months. Dishwasher detergent (particularly bargain dishwasher detergent) does etch glass. It doesn't causes scratches, it causes a hazing or loss of shinyness. Distinct scratches on plates come from knives and forks. If you pack your dishwasher such that glasses can rub up against other glasses when agitated by the dishwasher spray, that will cause scratches.
 
Warning! Never wash your knife in the dishwasher. I have bean following this discussion and when I was loading up the dishwasher today the thought came to me to put my full size griptillian in and see what would happen. I was wondering if it would dull the edge. I made sure it was nice and sharp before putting it in. I let it run the complete cycle including the dry and when it was done I reached in and pulled out a mini grip. I was thinking of getting one but not this way.


All kidding aside, the knife was not as sharp as it was when I put it in.
 
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