Cleaning a stainless steel thermos

Stan in Oly, WA

Well-known Member
I got a stainless steel thermos at a garage sale but it turned out that it was rusty inside. Is it possible to get rid of the rust easily (or at all)? It's not a big deal. If I can't get rid of the rust, I'm out $2, but it strikes me as an interesting problem, both from the point of not being able to use the methods I could use on the exterior surface, and for not wanting to put more effort into it than it warrants.

Stan
 
Something that might be worth a try, have seen it done with glass coffee pots in restaurants. Half a cup of crushed ice, juice from 1 lemon, enough water to make a slurry. Swirl it around for about 30 seconds. Glass pots come out sparkly clean, might work for stainless if just surface rust. The lemon juice dissolves the flim & sharp edges of ice helps scrape it loose.
Willie
 
If it's truly rust, phosphoric acid will remove rust from stainless steel. If you have any Ospho metal primer, you can try that. Or dump a bottle of Coca-Cola in it.

If it's actually coffee crud or some other beverage stain, washing soda (calcium carbonate) is very effective at removing coffee deposits.

I would start by dumping a couple tablespoons of washing soda in it, filling with hot water and allow it to sit overnight. Scrub it out with a bottle brush (if you have one) and rinse. If it's still rusty, hit it with phosphoric acid. If it is good quality 300 series stainless, any rust should be only a thin film.
 
>Good stainless will not rust.

Dusty, every yachtsman knows that "stainless merely stains less". In salt water, 304 and even 316 stainless fittings are notorious for weeping rust stains onto fiberglass boat hulls.
 
There isn't any stainless that won't rust under some conditions. That brings up a guy I used to work with. Bought a stainless Colt Gold Cup. Never so much as wiped it down after shooting in the rain, etc. Naturally he starts getting rust discoloration. He's po'd and ready to return it for a full refund, gonna sue Colt, etc. Took me the better part of an hour to convince him he was wrong, it was his fault, that he could fix it all with a little elbow grease and future care.

Some people...
 
Check the link below. We use to clean stainless sink, pans, etc. I get the powder which is like comet, making a paste, leaving it sit for a bit, then wash. Repeat if necessary, but usually one pass cleans it like new.
Bar Keepers Friend
 
Stan,fill it with milk and let stand for several days..the lactic acid in milk does wonders! My Mom had a set of tin fry pans and when they needed cleaning she put milk in them and set them in the back kitchen,they looked like new afterwards
 
>Washing soda is SODIUM carbonate, not calcium carbonate.

You are correct. Fortunately, laundry detergent and antacids are in different aisles at Kroger, so I usually get the right stuff. Tums do a terrible job of cleaning out coffee pots.
 
I had a "Film" in a stainless Steel Thermos, it
looked like rust, but was from coffee. A table-
spoon of baking soda, and fill it with boiling
water, from a teakettle, let it sit for 15 minutes, then rinse. the thermos came out
sparkling!
 
Fill it up with boiling water and let it sit half an hour to warm it up.
Dump out the water and put in 4 heaping tablespoon of baking soda, do this with thermos in the sink.
Fill thermos back up with boiling water, as it foams over, top it up until it is full.
Set the lid on it and leave it overnight.
Next day rinse it out.
Never thought it would work until I tried it, comes out like new, works on coffee pots, tea pots, mugs thermos etc.
 
I would try the baking soda first. It is easy and cheap.
On milking equipmnet we used to clean the stainless steel with sodium hypochloite(swimming pool chlorine). It comes in a 10 or 12 percent concentrate.
Now, I use it on rusty or stained stainless steel. Usually dilute it before use. Works most of the time. Problably also depends on what grade of stainless in the thermos. Make sure you do not have skin contact(it burns skin).
About $3 or 4$ dollars a gallon.
 
If it's a Stanley it's guaranteed for life and they will replace it. You need to call their help line and follow instructions. I've got 3 and 2 have been replaced several years ago. Don't use chlorine in them- stainless steel is just stainless, not impervious.
 
Why is so much chlorine used to clean stainless steel inside and outside in the food processing ingdustry?
 
I have a WW2 stanly 2.5 gallon from an unnamed
B-17 and all it ever gets is warm water and polident denture tablets as big as it is I use a handfull but for a small one 2 will work ,
and their non toxic too!!
 
I work in the food industry. Have been since 1986. It comes in big bottles, it works , and it is cheap. Also the health department says that you MUST use it. It kills everything it touches if mixed strong enough. When you vent the area it evaporates pretty easily. NOW... do NOT use commercial clorine that is a concentrate. That crap will kill you and every one that gets a wiff of the stuff. They use it in your drinking water to purify it. Yup train tank cars. Just think of WWI and the trench warfare. Gas attach stuff. Also idiots who mix clorine and ammonia! Jeffcat
 

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