By now you already know the secrets of cooking dinner in your dishwasher, but what about the after-meal clean up? Did your mom know what she was talking about when she said not to throw everything into that time-saving machine?

Actually, she was. Read this list and weep – then never make these dishwashing mistakes again.

1. Cast Iron Skillets


Photo courtesy of Flickr user Chiot’s Run

First of all, water + iron = rust. And no one wants a rusty skillet, especially if you paid good money for it.

A cast iron skillet must also be seasoned to work properly, which basically means that a layer of oil is baked into its surface to make it non-stick. This seasoning protects the material and prolongs the skillet’s lifetime.

When you stick a cast iron skillet in the dishwasher, you obliterate the seasoning and leave the skillet vulnerable to damage. Just don’t do it. Find out how to properly clean a cast iron skillet here.

2. Good Knives


Photo by Parisa Soraya

When I say good knives, I mean meat cleavers, steak knives and other super sharp cutlery that isn’t your typical butter knife.

You may not think about it, but dishwashers have some pretty high-pressure water running through them, and this high-pressure water will slowly but surely dull the blades.

Unless you feel like getting out your grinding stone every time you do the dishes, it’s best to (carefully) hand wash your good knives.

3. Non-Stick Pots and Pans


Photo by Charlotte Hull

Going along with the theme of dishwashers not playing well with others, non-stick pots and pans can join the club. What makes non-stick pots and pans so magical is the layer of Teflon, or polytetrafluoroethylene, that’s added to their surfaces.

While this surface is tough in terms of repelling food and making your job to clean them a lot easier, it doesn’t stand a chance against dishwasher detergent and high-pressure water. Don’t do it.

4. Wooden Kitchen Items


Photo by Amanda Gajdosik

This one surprised me. I’ve definitely thrown wooden spoons or cutting boards into the dishwasher before, but you bet I’m not making that mistake again.

So why not wooden items? Heat warps wood, and dishwashers definitely get toasty. When you stick something wooden in the dishwasher (even items with wooden handles), you run the risk of cracking or splitting the wood.

And if you put disfigured wood through a dry cycle, there’s a greater chance of bacteria nestling into the cracks. Ew.

5. Crystal


Photo by Devon Carlson

If you’re classy enough to have crystal drinkware (probably in the form of wine glasses), keep it far, far away from your dishwasher. Not only could the heat from a dish washing cycle crack or chip the fragile material, but it could also wear down the crystal’s natural shine.

And if you don’t have crystal drinkware? Remember this when you’re at home so you don’t ruin your mom’s favorite wine glasses.

6. Insulated Drinkware


Photo by Emily Moschowitz

In a perfect world you could have you coffee on-the-go and wash the travel mug in your dishwasher. But newsflash: this world ain’t perfect.

There’s usually a vacuum seal in travel cups between the inside and outside layers of material. This air pocket is ultimately what keeps your drink warm. If you stick your travel mug in the dishwasher, you could water log that seal and ruin the insulation power of your mug (which would render it pointless). No, thank you.

7. Soft Plastics


Photo by Amanda Gajdosik

If you’re savvy, you save your leftover yogurt, peanut butter and other random plastic containers to use them as Tupperware. It’s a great idea that saves money, but beware – if you put disposable plastics in your dishwasher, they could melt.

Oh, and before you get any hair-brained ideas about reusing your party gear, please hear me out. I actually know people who are too stingy to just buy a new pack of red Solo cups when they throw parties. That’s right, they wash them and reuse them – and more power to them. But they hand wash them.

Soft plastics (like the kind red Solo cups are made out of) absolutely cannot go through the dishwasher, either. This also applies to ping pong balls. Just rinse them off in the sink like a normal person.

While you could probably care less about the actual containers or cups being ruined, you may care a bit more about the plates and mugs that they melt all over. Yeah. Stay on the safe side with containers meant for a one-time use and wash them all by hand.

8. Hard Plastics


Photo courtesy of Flickr user Kathleen Franklin

It should be a general rule of thumb that plastic and heat do not mix. This rule contradicts some hard plastic brands that claim to be dishwasher safe, but it’s best to hand wash and dry them to avoid warping or melting.

But if you feel like living on the edge and putting your hard plastics in the dishwasher, make sure they’re upside down on the TOP rack so that they’re as far away from the heating element as possible. One melted plastic container will earn you a one-way ticket to Sears in search of a pricey replacement.

9. Glass Bottles


Photo by Jocelyn Hsu

As for beer bottles, wine bottles, liquor bottles, etc, it’s technically safe to put these through the dishwasher as long as any adhesive labels are removed and there aren’t any plastics involved.

But I really wouldn’t suggest doing it. Barely any water will even get into the bottles because their necks are so tiny, deeming it a waste of time, really.

These thin necks are also a hazard in terms of stability. If one of those puppies snaps and the bottle goes crashing into the heating element of your dishwasher, you can say buh-bye laziness and hello broken dishwasher.

10. Hand-Painted Glass


Photo courtesy of Flickr user Edward Peters

This one should be pretty obvious. Most painted glassware that you’re going to find at your nearest Wal-Mart aren’t going to be able to withstand the intensity of dishwasher detergent.

Dishwasher detergent is tough stuff and will completely strip away all of your hard work if you choose to put your hand-painted dishes through the dishwasher.

11. Disposable Aluminum


Photo by Morgan Chase

Disposable aluminum containers are great for BBQs and daylongs, but once the deed is done it’s time to part ways. Most aluminum that’s used to cook with has a thick coating to preserve the metal. When it comes to disposable aluminum, this coating is practically nonexistent because it’s intended for one-time use.

Putting it through the dishwasher will do a few things: the dishwasher will strip off the coating; the aluminum will be oxidized, which will result in black sticky residue all over the dishwasher; and the disposable aluminum will be warped and basically unrecognizable.

Use it once, pitch it and buy another one because it isn’t worth all of the hassle.

12. Anything with Adhesives


Photo courtesy of Flickr user Kacper Gunia

Adhesives can be tricky because no matter how many times the label says it’s waterproof, you can’t trust that this claim applies after five years of wear-and-tear.

Say whatever is adhered to the side of a glass comes loose while going through the dishwasher. This can cause mass mayhem in your dishwasher’s draining apparatus – AKA clogs on clogs on clogs.

Do yourself and your dishwasher a favor by hand-washing anything that has an adhesive involved.

As you can see, your dishwasher is a great way to free up some time while still getting your dishes clean. But you can’t rely on in it to do all of your dirty work. If you’re going to dish out the big bucks for your cookware, you might as well take the time to insure that it lasts for more than one lease.