Are Stainless Steel Cups Dishwasher Safe? – What You Need To Know

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Perfecting your favorite recipes comes with a pile of dirty dishes strewn around your kitchen, but fortunately, dishwashers exist! They offer respite by efficiently cleaning utensils of varying sizes and materials. Fortunately, that includes stainless steel cups.

Stainless steel cups are dishwasher safe because they can resist corrosion. A passive layer formed by chromium surrounds the stainless steel alloy, protecting it from significant damage. However, stainless steel cups can lose their shine over time when cleaned using a dishwasher. 

Stainless steel is one of the most common materials that are used to make dining utensils. So, in this article, I’ll outline everything you need to know about cleaning them in your dishwasher, include curated tips to help you preserve their quality for longer, and discuss the nagging subject of how they might be harmful to human health.

Are Stainless Steel Cups Dishwasher Safe?

Stainless steel cups (and other utensils) are dishwasher safe because they contain a substantial amount of chromium at about 11%, which is known to prevent corrosion effectively.

Let me give you explicit details of how this works: 

Stainless Steel Is a Ferrous Alloy

The common carbon steel starts to rust when exposed to humid conditions, but that isn’t the case for stainless steel. It’s a ferrous alloy that contains:

  • Iron
  • Chromium
  • Manganese
  • Silicon
  • Carbon
  • Nickel
  • Molybdenum

With such sturdy constituents, is it any surprise that stainless steel utensils last very long? However, chromium is the most important when it comes time to stave off undesirable rust, keeping the utensil in top-notch quality. 

How Chromium Protects Your Stainless Steel Utensils 

Chromium contained in stainless steel alloy makes up about 11% of the total material used. The chromium promotes passivation, the spontaneous creation of a thin inert film of chromium oxide that blocks oxygen diffusion to protect the entire material against corrosion.

So, you can confidently buy stunning stainless steel drinkware like these quaint Gusto Nostro Stemmed Wine Glasses from Amazon.com without fear that they aren’t dishwasher safe. However, keep in mind that your stainless steel cup may become less shiny after many washes in a dishwasher, but it won’t rust. 

How To Know if Your Drinkware Is Dishwasher Safe? 

Most manufacturers proclaim that their stainless steel drinkware, including cups, mugs, tumblers, and bottles, are dishwasher safe, but that isn’t always the case.

To know if your drinkware is dishwasher safe, look for the words “dishwasher safe” on the drinkware. It’s typically at the bottom or handle of the cup. Also, look for the “dishwasher safe” symbols. While they aren’t universal, they commonly feature plate(s) on a rack and a shower of water over them. 

Why Aren’t Stainless Steel Cups Dishwasher Safe?

While stainless steel cups are generally dishwasher safe, cleaning them in your dishwasher comes with some caveats.

Stainless steel cups aren’t dishwasher safe as they may sport streaks from contact with other materials in the machine. Dishwasher detergents are typically potent, and so they can damage the protecting coating of the stainless steel material. 

Prolonged use of a dishwasher to clean your stainless steel cups can also cause them to look grey as they lose their shiny finish.

Household Items You Shouldn’t Put in Your Dishwasher

Consumer Reports also states other household materials that should never go in your dishwasher: 

Wooden Utensils

The high temperature and intense water pressure in your dishwasher can cause the wooden utensils to become distorted and fade. So instead, wash them by hand using a nylon scrub, water, and soap. Let them dry fully out in the open air. 

Sharp Knives 

If your knives are sharp and you want them to remain that way, never place them in a dishwasher. The pressure will dull the edge of the knife, and in the worst-case scenario, they might damage other utensils in the machine.

Cast Iron Cookware

Dishwasher detergents are typically harsh and unfit for cast iron cookware, like this Cast Iron Skillet Set from Amazon.com that has a superior heat distribution. Using a dishwasher to clean the set can damage their non-stick coating so, instead, gently wash them with a soft sponge and mild soap. 

Brass and Bronze Utensils

Special utensils like those made out of brass and bronze should be cared for specially. In other words, never place them in your dishwasher. Wash them by hand and with a mild detergent to prevent damage to their beautiful coating and maintain their elegant appeal.

Copper Utensils

Like brass and bronze, utensils made of copper are special because they add a luxurious feel to your kitchen. A good example is this Gotham Steel 20 Piece Set from Amazon.com that has everything you need to run your kitchen. The cookware is lightweight and therefore very easy to use, but it also requires special care to maintain its beautiful finish.

So, don’t place them in a dishwasher or use abrasive materials that can taint their interior or exterior.

Insulated Mugs

Insulated mugs work to keep your drinks warm through a vacuum seal that’s sandwiched between their interior and exterior. 

Placing such a cup in a dishwasher causes the vacuum to expand between the two walls, so much more that it results in the loss of the vacuum and its heating effect. This phenomenon also applies to stainless steel cups that are insulated like these Beast tumblers. 

Note: If your stainless steel any of the materials outlined above, i.e. if it’s insulated, has a wooden, bronze, brass, or copper part, don’t place them in a dishwasher. 

How To Clean Stainless Steel Cups – Without Using a Dishwasher?

The most attractive feature of stainless steel cups is their lustrous finish, and if you’re like me, you’ve probably been doing your best not to destroy the finish. Fortunately, I found that caring for my stainless steel cups isn’t difficult to do.

To clean stainless steel cups without using a dishwasher, wash them by hand, using only a soft (non-abrasive) sponge. While they’re admittedly dishwasher safe, placing them in the machine alongside other utensils can leave streaks on them and, over time, erode the protective film on their surface. 

Here are more simple tips that’ll keep your stainless steel cups lustrous and long-lasting:

  • If you have stuck-on food bits on the utensil, let them sit while soaking in water for a while before washing. Alternatively, you can bring the water to a boil to soften the food bits quickly.
  • Give your stainless steel utensil an occasional polish to maintain its shiny finish. However, make sure you only use a soft abrasive cleansing powder. 
  • If you notice streaks on your stainless steel utensil use some steel wool to polish them thoroughly. 
  • You can remove the undesirable rainbow discoloration from overheating by washing with vinegar or using the pot for cooking a high-acid food, like tomato sauce.
  • For stubborn or burnt food spots make a thick baking soda and water paste and applying it to the utensil. Let the mixture sit for a few minutes before washing and rinsing off.