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Why can't I put knives in the dishwasher?

Posted by try_hard (My Page) on
Mon, Mar 24, 08 at 11:20

Over the years I've heard conflicting advice about caring for knives. Some people say you can put them through the dishwasher; others say they should only be hand-washed. I really dislike hand-washing and have always put mine through the diswasher - I lay them on the top rack, not in the cutlery basket. But I don't know if even the top rack will damage them. Can someone clear this up for me?

Thanks!
try_hard
...


Follow-Up Postings:

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RE: Why can't I put knives in the dishwasher?

Fine wood handled knives are ruined by the harsh detergents and temps, which includes loosening or seperating of the handles.

For safeties sake, they should be laid on top rack and smaller knives placed in utenstal trays should be pointed down. Many people have been seriously injured including kids that have died after tripping and falling on exposed blades.


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RE: Why can't I put knives in the dishwasher?

The DW will also ruin the edges on the blades of the knives. I'm talking here about good chef knives and steak knives, not necessarily your everyday cutlery.

A few years ago I won a set of really good steak knives in a raffle. They were made in Tuscany and donated by a local cutlery store. The owner of the store said that the man who made them didn't originally want them sold in the US because too many people put their good knives in the dishwasher. He made me promise to hand wash mine!


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RE: Why can't I put knives in the dishwasher?

You also risk damage to the DW rack, exposing the metal beneath the vinyl coating and promoting corrosion.


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RE: Why can't I put knives in the dishwasher?

Weissman: You said:

The DW will also ruin the edges on the blades of the knives.

That's exactly what I'm trying to understand -- how can the DW ruin the edges of the blades if the knife blade isn't touching anything in the dishwasher? I lay the knife with the top against the rack and the sharp side touching nothing.

I don't have any wood-handled knives but I have several knives that I paid $75 or more for (which is alot for me) and I don't want to ruin them but at the same time, if it's sitting securely in the DW and the sharp edge isn't touching anything, it's just being sprayed with water and soap, how is that dulling the edge?

I'm not challenging what you say, just trying to understand.

try_hard


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RE: Why can't I put knives in the dishwasher?

Are you saying your knives can't bounce around at all and that the sharp edge won't hit the racks or anything else? Bouncing against things will damage the edge. I don't know if the hot water/detergent will damage it as well.

I don't like doing dishes but washing knives by hand doesn't take that long.


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RE: Why can't I put knives in the dishwasher?

The simplest answer is it dulls the heck out of your good knives. I can notice a difference in cutting ability. if someone ONE time puts it the DW instead of hand cleaning, which takes no time at all if done when you are first done with the knife.


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RE: Why can't I put knives in the dishwasher?

There are two reasons why the DW can ruin the edges of your knives, as Weissman and others have pointed out.
First, the high temperature of the DW can re-temper the knife. Tempering during the manufacturing process is done to find the right balance between the steel's hardness and its brittleness. If it's too hard, the blade will be brittle and break. If it's too soft, it won't keep its edge. So the high temperature of the DW can change this balance.
Second, DW detergent can be highly caustic and can damage the steel.
Hope this helps.


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RE: Why can't I put knives in the dishwasher?

Thanks everyone, I now understand the reasons not to put good knives in the dishwasher.

try_hard


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RE: Why can't I put knives in the dishwasher?

I don't put my good knives in the dishwasher because my grandmother always said not to (she just said it dulled them and that was that) and was good enough for me. Though in recent years have come to understand why!!!!


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RE: Why can't I put knives in the dishwasher?

Tempering takes place at temperatures of at least 300 degrees F. One thinks the typical dishwasher, even super machines like the Miele, don't reach these temperatures. And I think one's good stainless would be just as damaged as one's knives if dish washing detergent were this harsh, yet my 10 year old set of very heavy weight, very nice stainless flatware is as shiny as ever. Wooden handles will crack even without running them through the dishwasher so no sense in accelerating the process by exposing them to the higher temperatures of the dishwasher. So I am gradually shifting to the molded plastic handles these days.

So we are left with bouncing and safety. Certainly can't argue with safety. Don't know how much stuff bounces around in a dish washer. I doubt if a good quality, heavy knife would bounce too much. Now if you laid a pile of dirty knives on top of each other in the rack, you would probably be asking for trouble, but I assume you use a block to store them and don't toss them loose into a drawer. Same principal. On Henkels' web site they recommend: "Do not put knives in the dishwasher. Banging against other cutlery or pots and pans will nick the blades." Not worried a bout loss of temper I guess. So if you want to put them in the dishwasher, do it carefully where they will not bang against other objects.

If you lay your chef's knife by itself carefully in the drop-down rack (if you have one) in the upper rack you are probably going to be OK. It certainly isn't going to ruin the knife; at worst you may have to sharpen is a little sooner. Just don't put them in a pile or mix smaller ones in the cutlery bins with your flatware. Any you may have a more sanitary product at the end of the day.


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RE: Why can't I put knives in the dishwasher?

A chef friend gave us knives for a wedding present in 1985. I couldn't possibly count the number of times they've been through the dishwasher. I haven't even had to sharpen them many times in those years. I also have to admit to having put my Chicago Cutlery and Henckel knives (also from our wedding) with wooden handles in the dw and they haven't cracked. I have a hard time believing that there is enough bouncing against the nylon coated racks to bother them, if any. I'm sure if I'd noticed enough problem, I would handwash them, but I have 8 kids and don't have time to baby anything that isn't living flesh and bone. Besides, I like them absolutely clean. (I also think it might be safer to have the kids put them in the dishwasher than have them try to handwash them)


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RE: Why can't I put knives in the dishwasher?

I'm guilty too...I put knives in the DW. The serrated paring knives go in with the cutlery and the bigger knives go on the upper shelf between tines so that they don't move around, blade up. Probably not the safest thing to do, but since it's me or DH unloading, that's what I do. Heck, I even put wood spoons in the DW.


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RE: Why can't I put knives in the dishwasher?

Olympic -it's gonna take a lot more than the 130 -200 deg. temps. household DW's produce to retemper a knife.

A blacksmith told me years ago that it's the prolonged exposure to water that dulls the knife's edge. This happens at the microscopic level and they are not going to come out blunt, but less sharp then if you hand washed and then dried them right away.


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RE: Why can't I put knives in the dishwasher?

Not sure about temps or DW detergent - however the biggest reason I don't put my good henckel knives in DW is the more places they go, counter, meat, counter, sink, dw, etc the more likely they will be dinged in the process - the sink is really the worst place because they are typically at the bottom then things tossed on top
So for that reason I try to wash by hand right after using -
Getting them professionally sharpened is a good idea too - i think i paid $2or $3 to get mine done last fall


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RE: Why can't I put knives in the dishwasher?

Just remember that all pro sharpeners are not the same. I had to buy new sewing scissors after having a pro sharpen them. One pair had a ding in the blade and it was much better before he 'fixed' it!


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RE: Why can't I put knives in the dishwasher?

you can put any of them in the dishwasher, if you want to accelerate their wear & tear. Rivets are typical culprits to go first. Next, if you have any wooden knives, they go even faster. If you have inexpensive knives & steak knives you probably shouldn't worry so much due to lower cost. We wash all of those in the d/w all the time. But the Pro S Henckels - I wash them by hand. Our Pro S utility knive was washed once in the d/w, and you can tell it's not as shiny or solid as the rest of the set.


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RE: Why can't I put knives in the dishwasher?

Other than a few older knives with wood handles, all mine go into the DW, and I've never had a problem with blades dulling or handles breaking. My DW has a small basket that I can attach to the top rack for knives, it works well.


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RE: Why can't I put knives in the dishwasher?

After my long posting, I have to admit I never put mine in the dishwasher. However, after I hand wash them, I steel them and if they go in the dishwasher, my wife empties it the next day and they don't get steeled. Never seem to have developed the habit of steeling before I use them for what ever reason.


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RE: Why can't I put knives in the dishwasher?

Agree with capecodcook, DW temps are too low for tempering to be a concern.

In years past, the handles of knives were plain wood, and would swell and loosen in the DW. Today, if wood is used for the handle, it is impregnated with resin for sanitary and strength reasons. Knife edges can be damaged by moving around in the DW, which means more frequent sharpening, which shortens the knifes life.

Cooking knives obviously become dirty, but they are generally more sanitary that eating utensils, because they are never put in contact with the mouth. This means that DW sanitation is not necessary for cooking knives.

This leaves safety as the primary reason NEVER to put cooking knives in the DW. In most culinary schools, you will flunk a course if you put a cooking knife in a DW or even worse, in a sink. Imagine being a dishwasher (human dishwasher, that is) and reaching around in a big sink with a sharp knife in the sink somewhere!

The correct way to wash a cooking knife is to hold it under running warm water and wipe with a sponge/cloth from heel to tip, with your hand above the back of the blade. If you do this, you will not be in danger, and neither will the knife, even if it slips.


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RE: Why can't I put knives in the dishwasher?

My knives cut raw chicken, raw pork, raw beef.

I want them to be clean. Dishwasher.

Knives are expendable supplies. If they need sharpened I sharpen them. If they need replaced I replace them.

Getting a little more life from knives that will last 5 to 10 years is not a good trade-off vis-a-vis bacteria growing on the blade or hilt that gets transferred to our food.


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RE: Why can't I put knives in the dishwasher?

My knives cut raw chicken, raw pork, raw beef.

so do everyone's. go to a butcher shop and ask them if they put their knives in the dishwasher. i guarantee they don't. restaurants cut meat with their knives and they serve hundreds of people each day--kids, the elderly, people with compromised immune systems, and they can be shut down for making people sick. no restaurant puts their knives through the dishwasher.

wash your knife with hot water and liquid dish soap and it'll be just as clean and bacteria-free as if it went through the dishwasher.

i never put my knives in the dishwasher, but the main reason is that we don't run the dishwasher every day and i don't want to have to wait until we need to run it and then the time for the cycle to run before i can use the knife again.

i wash my knife (i use one, primarily, for everything), wipe it dry, and put it away in the block after each individual use. sometimes i do this ten times in the course of making dinner. that's the habit i'm in. i like it to be there, ready and clean when i grab for it.

but, i'm a long-time restaurant line cook, and it becomes ingrained to put every single thing back in the same place every single time you use it. that way your hands can always just move to what you need, without your brain having to get involved. i realize that some might consider it a bit ocd.


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RE: Why can't I put knives in the dishwasher?

My knives cut raw chicken, raw pork, raw beef. I want them to be clean. Dishwasher.
Knives are expendable supplies. If they need sharpened I sharpen them. If they need replaced I replace them.
Getting a little more life from knives that will last 5 to 10 years is not a good trade-off vis-a-vis bacteria growing on the blade or hilt that gets transferred to our food.

First, dishwashers make things no more sanitary than does hand washing. In fact, home dishwashers (unlike commercial ones) contain NO sanitizing agent, so a DW is really no more sanitary than is hand washing, unless you use water at 180 F or higher. The Food Safety Code allows either type of washing to be used for any type of dishes, or tool.

If you want to sanitize your knives, after washing, dip them in a container that contains one cap (yes, cap, NOT cup) full of standard, plain bleach in a gallon of cold water. One minute in this solution will sanitize your knives. This solution must be made fresh daily, as the Chlorine dissipates over time.

Yes, knives can easily be replaced, but why waste money? Several knives in my house are 40+ years old, and almost all are 20+ years old.

As edlakin says, most cooks use one knife for everything. After cutting up some chickens, they (we) wash their knives, dry them, and store them. This storing dry helps kill bacteria by desiccation. After the chicken are cooked, they (we) use the same knife to cut the chicken into portions. Happens millions of time per day, and I don't see people keeling over in the streets daily from food borne illnesses.

So relax a little, and treat your knives to hand washing. They will thank you.


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RE: Why can't I put knives in the dishwasher?

Got a chuckle over the losing temper post. Nonsense.

I keep my knives very sharp. None of them ever touch anything except the food I'm cutting or the block or sheath where I keep them when I'm not using them. I clean them by hand -- which takes seconds. Haven't ever had any of them in the dishwasher. No family member or guest has been sickened from contamination in my home as long as I've been serving -- about four decades now.


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RE: Why can't I put knives in the dishwasher?

By food safety code I assume we are talking about the FDA's 2005 Food Code. It is interesting to read and get educated. Thanks.

Section 4.6, around page 29, speaks to cleaning utensils.

I still think I will use the dishwasher. It gets hotter than I can stand to put my hands in.

And just because retail establishments do it doesn't mean I would. Butchers do not cut raw vegtables after they cut meat and I cook most meat. Bars just dip glasses in the same soapy water followed by a "rinse dip" all night. Not what I do at home.

I prefer not to level with the lowest common denominator.

Here is a link that might be useful: 2005 FDA Food Code


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RE: Why can't I put knives in the dishwasher?

As far as the safety goes... does anyone really put a sharp knife in the dw with the blade pointing up? That just gives me the shivers. I don't even like forks to have the tines up, but that's the way my utensil basket takes forks.


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RE: Why can't I put knives in the dishwasher?

"does anyone really put a sharp knife in the dw with the blade pointing up?"

I have a friend who, after an expensive trip to the emergency room, no longer does so...


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RE: Why can't I put knives in the dishwasher?

I prefer not to level with the lowest common denominator.

if you think the way restaurants/bars clean is the "lowest common denominator", i think you have very little experience with how they do things.

restaurants and bars are held to a very high standard and have lots of money riding on not making people sick. most adhere to very strict HAACP standards that go far beyond the minimum requirements mandated by FDA or local codes.


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RE: Why can't I put knives in the dishwasher?

Restaurants/bars................

Man do I agree with that!


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RE: Why can't I put knives in the dishwasher?

Checked with my cutlery rep who is an expert knife sharpener, has his own cutlery store and was a butcher for years. Showed him the first dozen or so posts. He agreed completely with "capecodcook's" first post. It's the rivets on wooden handles expanding and contracting that in the dishwasher that ruins wooden handles over time. He didn't think it was terrible to put a non-wooden handled knife into the dishwasher - It might dull it very slightly but probably not enough to damage the knife. Safety/knife bouncing around are major concerns; both of us don't generally do it for that reason. I admit I have put nice non-wooden handle Henkel steak knives I bought in 1991 in the dishwasher (always in their own special knife compartment) in the silverware drawer. They're still in good shape. Great posts from cpovey and edlakin about care and sanitizing.


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RE: Why can't I put knives in the dishwasher?

Historically, non corrosion resisting steels could be brought to a sharper state than corrosion resisting steels (stainless) having high chromium and nickel content. In dishwasher conditions, water remained on the blade longer, causing microscopic rusting on the edges of such steels and thus dulling them.

This effect was well known to men in the days before high chromium razor blades, where drying the blade after shaving extended service relative to leaving it wet. One's face could tell.

kas


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RE: Why can't I put knives in the dishwasher?

good point, although those of us that use knives made of anything but the ubiquitous "high-carbon molybednium alloy" are a vanishing breed.

i use old-school sabatier carbon steel knives that do rust if left in contact with water for any length of time. yet another reason not to put them in the dishwasher. i had totally forgotten about that.


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