A stainless steel travel mug is a good investment because a quality mug can last for many years. When you have that favorite cup and carry it every day, you rapidly become attached to it and needing to find a different mug seems like abandoning an old friend. The trouble is that your old friend can sometimes become a bit soiled and even stinky if you fail to give it the care that it needs.
Many travel mugs come with “hand wash” only warnings, and only a few are dishwasher safe. One of the main reasons for this lies in the polypropylene and plastic parts that are attached to the outside of the mug. Poly parts are often used to make the threads at the top of the mug, plus handles or handle inserts, grip bands, etc. The reason many of these mugs are not dishwasher safe is that the shape of these parts can sometimes hold water, allowing contaminants to lie in a small channel around the inside of the mug. Hand washing eliminates this since you would normally turn the mug right side up to scrub it, then upside down to dump it, then right side up to rinse it, etc. this repeated turning allows all of the water to flow out of the mug to ensure that it is truly clean.
Stainless steel mugs can sometimes become stained by coffee, tea or other beverages. If you have an older cup that you want to rejuvenate and give some additional life to–or if you simply want to remove the stains–you can try one of these tricks.
The first is good old baking soda and vinegar. Take the lid off the mug and dump in one or two teaspoons full of baking soda. Then add a generous amount of vinegar. A couple good double-shots should get you started. The idea is to make the mixture foam up and clean the inside of the mug by the action of the baking soda being rapidly agitated against the metal. You can use any vinegar and any baking soda for this and the cheapest is just as good as the best. When finished, rinse the mug well and wash with soap and water. One word of caution: please remember when cleaning with baking soda and vinegar that this combination can build up pressure in a closed mug, so always leave the lid off for safety.
Another method that some people use is to drop a couple of ordinary denture cleaning tablets into a mug filled with water and then let the mug soak overnight. The tablets will not harm stainless steel and will blast coffee and tea stains right off–at least according to the television commercials.
One problem area to clean is the lid. Almost every stainless steel travel mug made comes with a polypropylene lid that is composed of several parts. Often, there are small spaces between the parts that can retain fluids even after the mug is empty.
For coffee and tea drinkers who take their drinks without additives, this is usually not much of a problem, just rinse the lid under hot running water and set it out to dry. Those who enjoy milk, cream or creamer, and sugar or sweeteners will find that cleaning the lids can be a bit more problematic. If left in the crevices of the lid, these additives can cause a sour taste or even become smelly. The good news is that most lids are made to be disassembled for cleaning. Watch for flip open spouts that can be popped off their hinges so you can get to the insides. Other lids with sliding doors will sometimes have a catch or a button that must be depressed to take the lid apart for cleaning.
In the odd event that the lid cannot be disassembled, you can try cleaning it in the same way that you would clean the rest of the mug, with baking soda and vinegar or denture tables. Just use a bowl or other container to hold the lid and cleaning compounds and be sure to rinse the lid really well under hot running water.