Knives safe in the dishwasher???

D

DMS1

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Jan 16, 2007
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I have always avoided this, had heard that the heat during the steam/dry cycle is hot enough to remove some of the temper (anneal?) a knife. The discussion came up the other day, with arguments on both sides.

Is there any truth to this, or any other reason to avoid the dish washer?
 
A dishwasher won't get hot enough to affect the temper of the steel, but the washing action tends to "bump" cutlery against one another dulling the edge. Also dishwasher detergent is corrosive and can damage some fiinishes.

Carbon steel is a definate no go since the knife takes so long to dry they will rust badly.

Wood handles do not survive well with repeated cleaning in a dishwasher.

Kevin
 
Dag-nabit said:
A dishwasher won't get hot enough to affect the temper of the steel, but the washing action tends to "bump" cutlery against one another dulling the edge. Also dishwasher detergent is corrosive and can damage some fiinishes.

Carbon steel is a definate no go since the knife takes so long to dry they will rust badly.

Wood handles do not survive well with repeated cleaning in a dishwasher.

Kevin
Click to expand...

What he said, with some additions.

I do put my kitchen cutlery in the dishwasher, especially those used to prepare raw meats (my boning knife, steak knife, etc. – these are "fibrox" handled, not wood). The dishwasher is a great sanitizer since it uses hotter water than your hands can stand (>130°F) and the detergent is quite caustic (basic on the "acid-base" pH scale).

In addition, one should always put the cutting edge UP. Putting the edge down allows draining water to remain on the edge longer, hastening dulling by erosion of the thin cutting surface. Most will always say "edge down for safety" and that's true but my family realizes I do edge up and nobody has been cut (besides, they're all knife savvy anyway).

Once out of the dishwasher, I give them a few light strokes on a ceramic rod and a couple more on a chrome butchers steel. Good as new and not a hint of nasty bacteria!
 
Id never put any high quality equipment in the dishwasher. This includes pots, pans, knives etc. It is a lazy treatment and does a lazy job--ie not good. It damages stuff by having strong detergents, steam, heat etc. If it would damage your hands, it probably aint good ffor a lo of other materials. If you dont care about haivng things last, go for it, but I bet it would cut the life of any item in half at the very best.
 
bruce said:
What he said, with some additions.

I do put my kitchen cutlery in the dishwasher, especially those used to prepare raw meats (my boning knife, steak knife, etc. – these are "fibrox" handled, not wood). The dishwasher is a great sanitizer since it uses hotter water than your hands can stand (>130°F) and the detergent is quite caustic (basic on the "acid-base" pH scale).

In addition, one should always put the cutting edge UP. Putting the edge down allows draining water to remain on the edge longer, hastening dulling by erosion of the thin cutting surface. Most will always say "edge down for safety" and that's true but my family realizes I do edge up and nobody has been cut (besides, they're all knife savvy anyway).

Once out of the dishwasher, I give them a few light strokes on a ceramic rod and a couple more on a chrome butchers steel. Good as new and not a hint of nasty bacteria!
Click to expand...

There is no need to put them in the dishwasher for sanitizing reasons. You have to get to 180 degrees F for it to be properly sanitized according to food safety guidelines IF you are using heat as as the sanitizing method. If you are that worried about it, iodine, chlorine, or quaternary ammonia will sanitize. One of these three is usually required by law to be used in a three-sink washing system or dishwasher at any U.S. restaurant.

Of course, any knives I have that can go in the dishwasher usually go in the dishwasher because I am lazy and I am not a restaurant. The longer wash times of home machines usually do a decent job.
 
There is no reason to ever put a knife in the dishwasher. It can damage the blade and handle, does not get hot enough to kill anything or effect your HT, the soap is harsh enough to make a sharp knife dull, and more than anything its a waste of time.
 
I would NEVER put any of my kitchen knives in the dishwasher. If you are worried about safety, why not put a shot glass full of Clorox in the sink with soapy water and wash everything with that?

Sometimes, I think we worry too much about "clean". My grandparents cooked three meals a day and the germs/bacteria didn't kill them until they were in their 90"s. I am doubtful that they followed any rules to disinfect anything. My former mother-in-law leaves the Thanksgiving turkey on the stove all day & evening, right beside a week old bowl of bacon grease. She's a surgical nurse. I suspect she'll die of something one day, but it won't be from turkey or bacon.
 
To affect the temper of a knife, you generally have to exceed about 350F; a dishwasher will not.

Dishwashing soap generally contains chlorine. Chlorine will attack even stainless steel. This will be most pronounced where the steel is very thin, i.e. the very cutting edge. You will literally wash away the edge. This is why knives dull in the dishwasher despite all efforts to keep them from knocking into each other. The dishwashing detergent literally washes the edge away and the high temperatures accellerate this. As a result, it is not a good idea to run any knives through the dishwasher.
 
I worry about germs as well but I would think simple water and wipe down with a clean rag (a little soap if you want) is good enough. After all germs washed away from your knife are.....well down the drain. And those few germs that remain have no base to reproduce and I would think die off from exposure to air. I don't know just my guess.
 
Let me clean up some of the "junk" science in the posts above.

1. There is no chlorine in dishwashing compound. The active ingredient is, in fact, caustic – like dilute sodium hydroxide. This is the opposite of an acid but every bit as effective in destroying bacteria, hydrolizing fats and proteins, and degrading a knife edge. A dishwasher works on a time/temperature interaction so the temperature (130-140°F) with dishwashing compound is as effective at killing micro-organisms as straight heat itself (180°F).

2. A sink of warm soapy water with a capful of laundry bleach (clorox, active ingredient - sodium hypochlorite) is also very effective at cleaning a knife and sanitizing it. It's just takes more personal labor.

3. A little soapy water and a rag are only partially effective in controlling bacteria. This approach doesn not kill them but the surfactants in the dish liquid tends to remove them from the knife (or dishes) and washes them down the drain. Some are left on the dishes and the rag but, hopefully, not a large enough dose to harm someone.

4. Food safety guidelines produced by the FDA, most state and city health departments that inspect restaurants, and the U.S. Army, accept the dishwasher as a method of sanitizing food contact surfaces. The three sink method (includes a near boiling final dip) or a chlorine dip are also acceptable.

As I stated, I do occasionally put my kitchen knives in the dishwasher, especially if I have been cutting poultry or other raw meat. I only have high quality stainless steel knives, no plain carbon steel blades, and no wood or bone handles – plastic only. I do not put my hunting or combat knives in the dishwasher – mostly because I do not cut food with them.

You are free to do as seems best to you, but do what you will armed with the facts and not hearsay or myth.

Suffice it to say I am qualified to be an "expert witness" on these matters.
 
DIshwashers are great for dishes and silverware, not smart to put your good knives in there though. You'd have to spend a lot of time drying them out so that they won't rust, the humidity inside the dishwasher can damage handles the soap may deteriorate them as well, the soap is corrosive and the humidity may also affect the speed of corosion. The knives will also bang around in there and cause damage to the edge. I'd just void it all together.
 
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