Stainless steel cleaning- thermos or teapot
Introduction
For stainless steel cleaning of thermoses and teapots, there are many cleaning agents available on-line . Bottle Bright, is an example, and it contains sodium bicarbonate and a magical concoction of other chemicals. This post is about simply using sodium hydroxide (caustic drain cleaner) to easily clean stainless steel surfaces that are not easily reached with a brush.
I carry a large thermos during ski trips. The pleasure of a hot or even warm drink under such cold conditions is wonderful. It can provide a surprisingly strong kick of energy and lift the spirits within a party of backcountry skiers. Sweet Mocha with plenty of milk is my favourite beverage while skiing and I can enjoy it with a clear conscience, knowing that I will expend so much energy that my blood glucose levels will not go high.
Unfortunately, such a thermos will become coated with a biofilm. With milky drinks, the biofilm, in my experience, spoils beverage quality during its storage by causing the sugars to become acidic.
Similarly, in a domestic situation, teacup bags are a fine invention, but I find that loose tea or tea bags in a teapot make a more satisfying, social and relaxing beverage. So a much-used stainless steel teapot is another drink container that benefits from a quick caustic cleaning. Some people argue that the tannin coating is not detrimental to the tea flavour, but I am sure that they would agree that it is unsightly.
Safety note: Sodium hydroxide is a hazardous chemical and should be handled with great care. If you already have it in your house as a drain cleaner then presumably you know how to use it safely by protecting your skin and eyes from contact with it.
I did start this cleaning procedure with my much-used or abused backcountry skiing thermos However, it is difficult to photograph inside a thermos to display its squeaky clean nature of the surface. Consequently, I moved on to cleaning an equally gungy teapot for which the photography was easy and it has become the featured image. The technique worked so well that l moved on to cleaning a quiver of much loved (and neglected) family thermoses. I was like a wizard with a new trick but needed to give constant reassurances about the ease with which the gunge along with the caustic residues could be easily and safely rinsed away down the drain. My taste test provided the final proof.
Squeaky clean stainless steel cleaning of a thermos and teapot
The thermos cleaning started with adding a teaspoon of sodium hydroxide (drain cleaner pellets or crystals or powder) to the rinsed thermos flask. “If you’re a tinkerer like me, you will probably have an old container of caustic drain cleaner in some safe place. Such containers usually leak in carbon dioxide from the air and some of the caustic will have reacted with it to form carbonates.”
The use of degraded caustic for this cleaning is just fine. Some of the caustic will be degraded to carbonate by reaction with carbon dioxide from the air during storage. Nevertheless, the carbonate is just another slightly inferior cleaning agent (as described above). Besides, this is a great use for crappy old caustic. soda that should not be used when making DIY sodium silicate for DIY refractories.”
Add a little bit of hot water to the flask. The reaction with the water will be violent as it will produce more heat. However, it will safely boil inside the flask. More hot water can be added to fill the flask right up to the top so that the entire inside of the flask is soaking in the caustic solution. Using a stainless steel kitchen sink is ideal for this operation as any spills can be flushed down the drain and skin contact can be avoided by rinsing the outside of the flask with plenty of water.
The caustic solution will immediately start to dissolve the biofilm and darken the cleaning liquid. If possible, I leave the flask to soak overnight, but I am sure a shorter soaking period would be satisfactory. The next morning, I decant the cleaning solution and flush it away with plenty of water, while also rinsing the flask with several loads of fresh water. The used cleaning solution can also be used to clean multiple other stainless steel items.
Tim
