Cleaning a Thermos Flask

Like bottles, thermos flasks prove to be an extremely difficult item to clean. They are often deep, and the bottom is very hard to scrub. Maybe one day someone will make a specially designed tool to clean the inside of a thermos, but until that day comes, we have to make do with the tools that we have. With almost any sort of cleaning task, the most basic items to use are soap and water, so let us start with those. I find the easiest way to clean a thermos flask is to pour hot soapy water into the bottle. Allow the soapy water to soak for a few minutes.

After the thermos has been soaking in water for several minutes, find a small dishcloth and a wooden spoon with a long handle. Wrap the dishcloth around the end of the wooden spoon. Push the cloth end against the inside of the flask, starting with the neck of the thermos. If you twist the spoon in the cloth, it will help make a bigger scrubbing tool. Make sure to rub the entire interior of the bottle. The hardest part is still the bottom of the thermos, but if you rub around enough of the bottom, everything should come right off. To get the cloth out of the thermos, tip it upside down and coax the cloth out using a combination of shaking the flask and prodding the cloth with the wooden spoon. It should come out fairly easily. Finish off the job by rinsing the now clean thermos flask.

Another idea for cleaning your Thermos flask is to fill it with very hot water and add four Polident (denture cleaning) tablets. Let it sit over night, and rinse it out in the morning. A thorough rinsing job should remove the need for scrubbing on the inside.

Do not store the flask with the lid tight between uses. It is best to leave the lid off to help prevent odors from building up inside, especially if the thermos is at all wet inside. That moist, warm, dark environment is perfect for bacteria growth, which will mean you have to clean the thermos out again before use.