Many need a hot cup of coffee to start the day; however, the morning rush often necessitates taking that cup of coffee on the go in a thermos. Unfortunately, repeated use can leave your thermos stained with a seemingly permanent coffee stain. If your daily coffee ritual is starting to discolor your thermos, it is time for a little maintenance. A simple mixture using ingredients in your pantry will remove coffee stains and prepare your thermos for the next cup.
Combine the hot water, vinegar and baking soda in a sink or container large enough to hold the thermos. Submerge the thermos in the water and leave it to soak 15 to 20 minutes.
Dip the sponge in the water and squeeze out any excess moisture. Remove the thermos from the water and drain it.
Wipe away any remaining coffee residue with the sponge. If the residue does not wipe away, soak the thermos another 10 minutes. Repeat until the residue is completely removed.
Drain the water from the sink. Thoroughly rinse the thermos until the water runs clear. Wash the thermos as normal.