Effect of dishwasher on knives, wood, non-stick, etc.

[annabelle]

I rinse my dishes and glasses before putting them in the dishwasher. I also run it every night and sometimes during the day if I am doing a lot of prep or feeding houseguests.

Katie Meadow, in the past ten years we have bought three dishwashers after deciding to replace the relic that came with the house. It has been the electrical components that control the cycles of the washers that have failed and not the electical heating elements or the wands. The contacts failed to make sufficient contact after brief (six months) use and Hubs took the box apart and fixed it twice. Previous to that, we had one that had a knob the was used to dial up the cycle and a small child who loved to fiddle. That was likely human error, not the dishwasher's fault that it died. We then replaced that one with the one we have now that seems to be hanging in there after three years use and a now older child who has lost interest in it.

[OliverB]

I never put wooden cutting boards in, but they'd never fit anyways, so it's a non issue. Since there is a chance my expensive knife might get damaged, I'm not putting $250 in there to find out, I rinse it off and hang it back on it's magnet strip, quick, easy, and not thoughts spent on it. (despite the fact that Shun rates it as dishwasher safe, it's my favorite toy, so I treat it different than the rest of the stuff)

I never put my non stick pan in either, it would take up half of the lower rack, I'd rather put other stuff there and rinse the pan out, which takes a good 30 sec or so, as I don't care what the chrome outside looks like - actually prefer a "well used" over a "brand new and polished with mouse leather" look

Other than that, everything goes in, and if it doesn't survive I throw it out. I have the same mantra with house and yard plants, if it can't survive w/o special care (covered in winter etc) it will be replaced with something that can.

New dishwashers did away with the plastic on top shelf only as well, which is nice.

Oh, yes, cast iron will rust, I would guess it's the salts and what not in the soap and then the wet storage until dry. You should be able to save that thing easily though, if really bad get one of those steel wool with soap in it scrubbers (forget the brand name) and go at it, then put something like crisco all over and stick it in the oven to season it. My cast iron pan never sees soap, only hot water and a good scrubbing with a brush, then wiped off with paper towels immediately while still hot from the water, the residual heat dries off the last bit of water.

I don't own any crystal, if I did put it in as well, same philosophy I have with plants. If it doesn't work the way I want, it has no place in my house

[Edward J]

Wood cutting boards:

-Wood is a natural material, it swells with moisture/humidty and shrinks in dry enviroments. This happens with 300 and 500 year old furniture as well as modern kiln dried wood. No body has been able to stop wood movement--other than impregnating the wood with acrylics--so the natual thing to do is expect and make adjustments for wood movement. A cutting board is usually made up of several pieces of wood which are glued together. The glue is waterproof, but will eventually fail becasue of the high heat and steam generated in the d/washer. Almost always a wood cutting baord that has been washed in a d/washer will crack and fail at the glue joints, starting first at the edges, then weakening along the glue joint untill it falls apart or the joint is so wide the it just traps crud.

Knives: As others have said, the edges invariably bang on something else. Only a diamond can cut another diamond, and only something as hard as the knive's steel can damage the edge of the knife. If the handle is wood, if will suffer the same fate as wood cutting boards and will shrink away from the steel, causing big gaps in which crud can fall into. Also, if the handle is wood and riveted on with copper rivets, the rivets will loosen. As the wood swells and shrinks, the wood fibers around the rivet are compressed and fatigued, leaving the rivet to rattle around in a larger hole. Kind of the same thing on why you should't soak and axe head in water to tighten it onto the handle. I belive Mr. A. Licoln found this out the hard way.

Of course, if the handle is plastic, or all metal, this damage won't happen, it's just that the edges will be exposed in the d/washer. For small paring knives this is no big deal, as they sit in a plastic divider and can only bang around on plastic surfaces in the d/washer.

Non-stick frying pans: Most mnfctrs have, or used to have a caveat about only washing the pan in water--no soaps or detergents. I do know that with older styles of teflon pans, high heat and soaps would render the pan pretty much useless. I don't know if that is true today, I haven't bought a non-stick pan for about 10 years now.

[Shel_B]

I found a good looking cast iron skillet in an antique store but it was so gunked up that I would not want to use it -as is- so I ran it through a full cycle in the dishwasher. It came out as bare iron and rusted. If is dishwasher can do that, I expect a putting a non stick skillet in would be somewhat akin to using a sand blaster on it.

Although some of the new non-stick is advertisxed as dishwasher safe. Some new Calphalon pieces come to mind. http://www.calphalon.com/ProductSupport/Use%20and%20Care/UseCareDisplay.aspx?UseCarePageID=17

Edited January 2, 2012 by Shel_B (log)

[FauxPas]

I also use bamboo spoons. I specifically bought them because they can be washed in the dishwasher. They hold up pretty well.

[slkinsey]

Wood: Repeatedly soaking and drying wood isn't good for the wood.

Knives: Dishwasher detergent contains abrasives. These will dull the edges.

Nonstick pans: Nonstick coatings are delicate and depend upon smoothness for much of their nonstick properties. The abrasives in dishwasher detergent rough up nonstick coatings and reduce their nonstick properties.

[boilsover]

Hi, Edward J: "Only a diamond can cut another diamond, and only something as hard as the knive's [sic] steel can damage the edge of the knife."

False and false. Diamonds are cut with a rap on a steel wedge, and cutting enough tomatoes can damage the edge of a knife. You can cut diamonds with water, and you can erode hardened toolsteel with plastic beads. The manila rope used in bladesmith certifications is always softer than any of the tested blades, but it dulls blades fast. Heck, even cardboard is hell on knives--that's why it makes a good strop.

In my opinion, DWers are just physical and chemical sandblasters, albeit weak ones. Some things, like SS-clad cookware, hold up pretty well, but they are wearing infinitessimally, too. Glass fares OK--for awhile. Wood, even impregnated and laminates, is usually the first to go bad under the onslaught. To me, washing anything valuable in a DW is like washing a nice car using a pressure washer.

Folks would also do well to remember that "stainless" steels are rarely completely so--this comes as an expensive shock to those who have lost a $$$ Falk saucier to mere table salt (Falk will not replace it, and rightfully so).

[Dakki]

Hi, Edward J: "Only a diamond can cut another diamond, and only something as hard as the knive's [sic] steel can damage the edge of the knife."

False and false. Diamonds are cut with a rap on a steel wedge, and cutting enough tomatoes can damage the edge of a knife. You can cut diamonds with water, and you can erode hardened toolsteel with plastic beads. The manila rope used in bladesmith certifications is always softer than any of the tested blades, but it dulls blades fast. Heck, even cardboard is hell on knives--that's why it makes a good strop.

FWIW I think Edward J is technically right - only a harder material will cut a given material - but he's ignoring fracturing (chipping and breaking), which will occur against any material if you hit it hard enough. One of the first things you learn about steel is that the harder it is the less tough it is likely to be, and a thin, hard edge like we want on a good knife is going to be fragile indeed.

The manila rope and cardboard thing is due to abrasive particles in the material, IIRC. It's a bit like having the abrasive from sandpaper suspended in jell-o - the material is very soft, but it wears things down very fast.

[GlowingGhoul]

When I have a pile of enameled cast iron cookware to clean, I run it through my dishwasher with the "hi temp" option selected, as well as "sani rinse", and NO DETERGENT.

These two heat the water significantly hotter than a standard wash cycle, and there is no risk of damage. With the exception of baked on food, they come out perfectly clean, and are not harmed at all. In fact, I'd bet handwashing is far more likely to mar the enamel than this method.

On occasion, I'll run my Henkels Twin Cuisine knives through a detergentless run as well. Knives laid flat, blades facing up of course. After doing this for many years, there's absolutely no sign of deterioration on the knives (they have composite handles).

I'm surprised there isn't a dishwasher equivalent of Woolite, for items that can safely be immersed in water but suffer from the chemical etching of regular, harsh detergents.

[HowardLi]

When two dissimilar metals are in an electrolytic (acidic or alkaline) solution, galvanic (corrosion) action can occur.

You never know when you might have two dissimilar metal in the dishwasher.

dcarch

This is a valid point. You never know when another metal might be touching the knife, even in a "safe" area. The high heat increases reaction speeds too.

[HowardLi]

Hi, Edward J: "Only a diamond can cut another diamond, and only something as hard as the knive's [sic] steel can damage the edge of the knife."

False and false. Diamonds are cut with a rap on a steel wedge, and cutting enough tomatoes can damage the edge of a knife. You can cut diamonds with water, and you can erode hardened toolsteel with plastic beads. The manila rope used in bladesmith certifications is always softer than any of the tested blades, but it dulls blades fast. Heck, even cardboard is hell on knives--that's why it makes a good strop.

Diamonds are cleaved, not cut, with steel implements.

I would have to say that it's impossible to wear a diamond with pure water unless the force of the jet impingement is strong enough to subject the material to plastic, not elastic, deformation.

If the plastic beads are glass-reinforced, sure. Otherwise, I don't see how the effect could be significant (though high impact energies may cause surface fatigue to set in).

Edited January 4, 2012 by HowardLi (log)

[mgaretz]

Hi, Edward J: "Only a diamond can cut another diamond, and only something as hard as the knive's [sic] steel can damage the edge of the knife."

False and false. Diamonds are cut with a rap on a steel wedge, and cutting enough tomatoes can damage the edge of a knife. You can cut diamonds with water, and you can erode hardened toolsteel with plastic beads. The manila rope used in bladesmith certifications is always softer than any of the tested blades, but it dulls blades fast. Heck, even cardboard is hell on knives--that's why it makes a good strop.

Diamonds are cleaved, not cut, with steel implements.

I would have to say that it's impossible to wear a diamond with pure water unless the force of the jet impingement is strong enough to subject the material to plastic, not elastic, deformation.

If the plastic beads are glass-reinforced, sure. Otherwise, I don't see how the effect could be significant (though high impact energies may cause surface fatigue to set in).

To set the record straight, diamonds are both cleaved along their grain and also cut (sawn really) with diamond on metal for any cut that isn't on the grain. For a gem diamond both of these are only used to get the diamond into a rough block. The facets (all the angly edges on a finished stone) are created by grinding using diamond on a metal disk and then polished with finer grits of diamond the same way. The grinding and polishing steps are identical in function to how we put an edge on a knife. In the gem world this is called lapping, and almost all faceted gems are created in a similar fashion, but diamonds use specialized versions of the equipment because of their hardness. But diamonds aren't tough, which is why you can cleave them with a gentle tap if done just right (and usually they saw a little groove so the tool doesn't slip).

[HowardLi]

I'm not disagreeing with you. But, to clarify my earlier statement, I was merely pointing out that steel cannot cut diamond, and is only used to cleave it.

[Porthos]

In my kitchen only one knife goes into a single compartment in the dishwasher and then I will also put 1 or 2 wooden or plastic spoons in that compartment positioned by the spine of the knife.

Part of my decision to hand wash or put the knife into the dishwasher is based upon what has been cut. If I've just prepped some veggies I may choose to hand-wash the knife and put it away but if meat of any ilk is involved then I want the much deeper cleaning action of the dishwasher. Just me in my kitchen.

For me knifes, bowls, pots and pans, etc. are tools to be used and I don't expect I will ever purchase anything that I would be afraid of damaging because of the cost of acquisition. But that's me and I leave lots of room for others to run their kitchen differently.

[phatj]

I also use bamboo spoons. I specifically bought them because they can be washed in the dishwasher. They hold up pretty well.

Interesting, I have a couple of fairly nice bamboo spoons (for Wal-Mart purchases, anyway) that are the only wooden implements I own that I won't put in the diswasher. The rest are sub-$1 implements that are basically disposable - they wear out from use before showing significant water damage.

[Porthos]

Here's a picture of the utensil basket in my dishwasher (it's in the door of the machine) showing how my knives don't bang against other things. The 10" chef's knife is 29 years old and going strong.