How to clean stains from inside of vacuum flask?

Question

I use my vacuum flask to bring my lunch to work. I've been doing this almost every day for half an year or so. Now there are some sediments or stains in the bottom of the flask although I wash the flask almost always immediately after it's emptied.

How can I get rid of the stain and smell inside the flask? I even used steel wool on a stick but could't make it clean 100% and I don't want to scratch it too much inside. Because I use it for food I am not sure if bleach is a good choice to go for.

Update

I have original Thermos made of stainless steel interior and exterior. Something like that one http://www.thermos.com/products/vacuum-insulated-10-oz-food-jar.aspx

Note that I am located in Austaralia so no cleaning products are available to me.

What is your thermos flask made of? Stainless, plastic, or something else? — derobert, Dec 18 '12 at 16:38

franko · Answer 1 · 2012-12-18T20:25:51.893

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I have found that a tablespoon of Oxy Clean followed by boiling water will remove even the harshest stains inside a vacuum bottle. Fill it to the brim (it will bubble and overflow, so do it in a sink), let it sit for a bit, then rinse very very well, and you will be amazed, I promise. I do this periodically to remove the coffee stains inside our steel thermos flask. [Edited for typos]

edited Dec 18 '12 at 20:25

answered Dec 18 '12 at 00:21

franko

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Looks like we don't have Oxy Clean here in Australia. – Radek Dec 18 '12 at 04:50
Maybe there's a local equivalent, under a different name? This page suggests a (liquid) product called Preen Oxyaction: http://answers.yahoo.com/question/index?qid=20071218113902AA6rLV9 -- not sure of the ratio of a liquid product to water, so you may have to experiment. I buy a powder version. – franko Dec 18 '12 at 14:46
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"Oxy clean" is a brand name. But any peroxide-based bleach will do. (Take care not to use chlorine-based bleach). – rumtscho Dec 18 '12 at 15:08
@rumtscho: Great suggestion! This is a quote from Thermos website `"DO NOT use bleach or cleaners containing chlorine on any parts of the product."` – Radek Dec 18 '12 at 21:35
Re: Rumtscho's suggestion, you could try soaking it in a water/hydrogen peroxide mix. – daisy_ann Dec 19 '12 at 00:03
This reminds me: I've been using a hydrogen peroxide and lemon juice mix (1 part of each with 6 parts water) as a non-chlorine bleach/whitener for my laundry, which seems to work well enough. So maybe a lemon juice/peroxide/boiling water mix would work here, too. – franko Dec 19 '12 at 00:45
Lemon juice means freshly squeezed juice? – Radek Dec 19 '12 at 02:12
I actually have been using just the bottled kind, but I'm sure fresh would be even better. – franko Dec 19 '12 at 04:47

score 4 · Answer 2 · answered Dec 18 '12 at 22:24

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A combination of coarse salt and vinegar is usually very effective. The coarse salt is used as an abrasive.

answered Dec 18 '12 at 22:24

soegaard

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Salt also reacts chemically with vinegar to make a stronger acid: http://chemistry.stackexchange.com/questions/2765/salt-in-vinegar-to-clean-pennies – john3103 Oct 09 '14 at 15:13
Likely stains are embedded in hard water build up, mineral salts. A good long soak in vinegar/NaCl should dissolve the mineral deposits. Stainless will not mind an overnight soak, and it is *much* easier than trying to get the stuff off with steel wool. – Wayfaring Stranger Oct 09 '14 at 16:59

score 3 · Answer 3 · answered Dec 18 '12 at 00:35

3

I would scrub it with baking soda.

answered Dec 18 '12 at 00:35

daisy_ann

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score 2 · Answer 4 · edited Dec 16 '13 at 12:28

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Try a Steradent (or similar denture cleaning tablet) or two in hot/boiling water. Will froth up, so do in sink until it settles.

Steradents are available from any good local supermarket in the Oral care section. Designed for dentures so safe for food/drink containers. Great for cleaning many kitchen utilities such as electric jugs etc.

edited Dec 16 '13 at 12:28

Community

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answered Apr 08 '13 at 10:02

Catalastic

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score -1 · Answer 5 · edited Oct 09 '14 at 22:21

-1

Thermoclean (available in the UK) is meant specifically for cleaning vacuum flasks.

edited Oct 09 '14 at 22:21

Cascabel

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answered Oct 09 '14 at 14:03

Rod Cope

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How to clean stains from inside of vacuum flask?

Update

5 Answers5