Are Thermos Products Dishwasher Safe? (Find Out Now!)

Jessica Stone
by Jessica Stone

The products produced by Thermos are excellent for keeping food and beverages hot or cold all day long. But, how do you properly care for a Thermos tumbler, mug, or water bottle? Are Thermos products dishwasher safe?

Whether or not a Thermos is dishwasher safe will depend on the specific product, as Thermos features a detailed Care and Use manual for each of their products. While most Thermos products are top-rack dishwasher safe, it is highly advised that you still hand wash them to keep their finish looking great for longer.

With that said, continue reading for all there is to know about effectively cleaning and caring for your Thermos.

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What is Thermos?

By definition, thermos is a term used to describe any portable vacuum-insulated container. These containers, whether they’re jars, bottles, or flasks, have a vacuum between an inner and outer wall that is used to keep the contents hot or cold.

Thermos LLC, on the other hand, is a manufacturer of these insulated food and beverage containers. They were founded in Germany in 1904, at which time they were the first company to create consumer products that used vacuum insulation.

How Do You Know If Your Thermos is Dishwasher Safe?

Similar to any other product you use, thermoses require special care and maintenance. The construction of these containers can make cleaning them a bit difficult and confusing. So, how do you know whether or not you can put your Thermos in the dishwasher without the risk of ruining the insulation?

Fortunately, Thermos states this information directly on their website under each products’ individual Care and Use instructions. For example, the care page for their stainless steel mugs and tumblers states the following:

“This product is top-rack dishwasher safe; however, hand washing is recommended as the dishwasher uses harsher detergents and hot water that may affect the appearance of your product…”

The same is true for most of their other products, including the attached components such as gaskets, lid parts, straws, and container parts. These items are top-rack dishwasher safe, but hand washing is highly recommended to ensure a thorough cleaning. It’s very easy for foods, liquids, or other debris to become trapped in between these parts, and hand washing delivers the best clean.

What Happens If You Put a Thermos in The Dishwasher?

If you were to actually run your thermos through a cycle in your dishwasher, what could happen? So long as the manufacturer states that the thermos is top-rack dishwasher safe, placing it on the top rack of the dishwasher will not yield any undesirable results. However, over time, it can slowly start to deteriorate or discolor the exterior finish on the thermos.

On the other hand, if you were to place your thermos on the bottom rack of the dishwasher, it’s likely that the space between the outer and inner layers will fill with water. This can cause damage to the vacuum seal and result in your thermos no longer having the ability to insulate properly.

When it comes to all the various components of a thermos, such as the lid parts, straw, and rubber gasket, these should also be hand washed for best results. If you were to place any of these components in the dishwasher, it simply won’t be able to clean all of the residual liquids, food, and gunk that gets trapped in between the parts.

How to Properly Clean a Thermos

General care for a thermos is crucial to longevity. Follow these steps as a daily thermos cleaning routine:

  • Fill the thermos with warm water and a couple of squirts of mild dish detergent. It’s best to fill the thermos, rather than completely submerging it in water.
  • Let the water sit for about three to five minutes to dislodge grime.
  • Wrap a dishrag or soft, microfiber cloth around a bottle scrubber and gently scrub the inside of the container. If you still have stuck-on food inside, use the scrubber on its own.
  • Rinse thoroughly with warm water.
  • Wipe the inside of the thermos as best you can and leave it out to air dry completely before use.

How to Remove Stains Inside a Thermos?

If you notice discoloration inside of your thermos, it’s almost always caused by coffee or tea build-up. In this case, denture tablets or coffee pot cleaner are often the best choice for removing stains and unpleasant odors.

Simply place two denture tablets into the thermos product along with hot water. Let this soak overnight and then wash with soap and water, rinse thoroughly, and allow plenty of time for the thermos to dry.

Pro Tip: If you have any undesirable smells coming from your thermos product, try using lemon juice! Lemon juice is excellent at removing odors.

Thermos Do’s & Don’ts

When it comes to maintaining your Thermos product, keep these do’s and don’ts in mind:

  • DO clean your thermos before the first use and as soon as possible after each use to prevent bacteria and odors.
  • DO NOT use abrasive cleaners, scrubbers, or cleaning products as they can dull the finish. This means you should avoid bleach and any cleaners that contain chlorine.
  • DO use a bottle brush for effective cleaning.
  • DO NOT use these products in a microwave, on a stove-top, or in any sort of oven.
  • DO try to maintain an upright position when carrying or transporting a thermos.
  • DO NOT put the product in a freezer.
  • DO hand wash all components of your thermos, whether they are dishwasher safe or not.
  • DO NOT leave contents in the container for longer than 24 hours.
  • DO always let the thermos air dry completely upside down with the cap removed.
  • DO NOT overfill the container.

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Related Questions

Do thermos products have an interior coating?

No, Thermos brand products do not have any sort of interior coating.

Are Thermos products lead-free?

Thermos products go through rigorous testing to ensure that they pose no risk of lead exposure to consumers.

Can you put milk in a stainless steel Thermos?

Yes, you can store milk in your thermos but it must be either below 40 degrees or above 140 degrees Fahrenheit.

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Jessica Stone
Jessica Stone

Jessica considers herself a home improvement and design enthusiast. She grew up surrounded by constant home improvement projects and owes most of what she knows to helping her dad renovate her childhood home. Being a Los Angeles resident, Jessica spends a lot of her time looking for her next DIY project and sharing her love for home design.

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