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#1 2007-01-24 08:18:40

C M Edwards
Member
From: Lake Charles LA USA
Registered: 2002-04-29
Posts: 1,012

Re: Microwave ovens for clothes washing

Because they can't actually get to steam temperatures using tapwater, actual sterilization would require the use of oils, but it turns out that microwaves are still very good at disinfecting common household items.

Experiment Demonstrates Microwave Ovens Will "Sterilize" Kitchen Sponges

It's also been tried with limited success for utensils and glassware, including syringes.

The near boiling temperatures microwaves can induce in kitchen sponges will inhibit bacterial growth and destroy viruses.  This should also work for other fabrics as well, such as the newly washed clothing of a Mars expedition's crew.  The amount of water required is not large, and this could easily become a means of extending the necessary supply of disinfectants that the crew will need to bring with them, using electrical power instead of cleansers for some applications.

I'm going to run home and try this, to see if I can stretch the lifetime of my sponges this way.


"We go big, or we don't go."  - GCNRevenger

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#2 2007-01-24 20:58:30

dicktice
Member
From: Nova Scotia, Canada
Registered: 2002-11-01
Posts: 1,764

Re: Microwave ovens for clothes washing

This is obligatory in our household: the last thing we do after washing up, is to squeeze the water out of the dishcloth and throw it into the microwave oven for up to 10 seconds on high, take it out (ouch, that's hot!) and drape it over the tap to steam itself dry. Works a treat!

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#3 2007-01-25 02:04:04

Rxke
Member
From: Belgium
Registered: 2003-11-03
Posts: 3,669

Re: Microwave ovens for clothes washing

But it's only effective after one whole minute on its highest setting if you want it sterilised, Dicktice. (and you then would have to make sure it isn't too dry or you get fireworks)

This could be interesting on ISS, for the swabs (or whatchacallit) they use to clean the interior surfaces that get damp due to condensation. might save them a couple of kilogrammes a year in cleaning rags... reuse instead of always throwing stuff away...

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#4 2007-01-25 05:07:10

Rxke
Member
From: Belgium
Registered: 2003-11-03
Posts: 3,669

Re: Microwave ovens for clothes washing

http://edition.cnn.com/2007/HEALTH/01/2 … index.html

people trying this at home with disastrous results...

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#5 2007-01-25 11:37:37

dicktice
Member
From: Nova Scotia, Canada
Registered: 2002-11-01
Posts: 1,764

Re: Microwave ovens for clothes washing

I should have emphasized: we use cotton dishclothes, not plastic.

EDIT 1: We frequently microwave refrigerated peanut butter in the jar for a short time just to soften it up. Once I left the plastic cap on it, and it caught fire before I caught my mistake, and kinda messed up our microwave oven. A lot of practical research could be done by the Mars Society on "microwave washing" and reported in this thread.

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#6 2007-01-25 12:22:11

C M Edwards
Member
From: Lake Charles LA USA
Registered: 2002-04-29
Posts: 1,012

Re: Microwave ovens for clothes washing

Rxke, that surprises me.

Microwave ovens work by using essentially the same principle as a radio receiver: radiofrequency radiation creates electric current in conductors.  It's the current that heats the food.  That's why forks and metal trim will spark, CD's develop St. Elmo's Fire, and paper containers won't burn in the microwave.  It's why wet foods heat faster in the microwave, and why <20mL distilled water doesn't superheat and blow up as fast as tapwater would.

Dry plastic and dry cellulose are just no fun in a microwave.

Dry sponges are not good conductors.  I would have expected that a completely dry sponge would do nothing but sit there. 

This tale of one catching fire after only 2 minutes under otherwise normal microwave oven conditions is not believable.  10 minutes would be remarkable. 

I wonder if there was more to it?


"We go big, or we don't go."  - GCNRevenger

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#7 2007-01-26 16:40:01

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,879

Re: Microwave ovens for clothes washing

I had a colleague who once put whole eggs in a microwave since he was told it heated them internally. It took him at least 30 minutes to clean the oven after the explosions.

Microwaves are very effective things if treated right but plastics can melt and microwaves treat substances differently depending on the nature of the material. We actualy once considered using them to set concrete for buildings. But found that they caused catastrophic damage and actually threatened health.


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#8 2007-01-27 08:11:57

Rxke
Member
From: Belgium
Registered: 2003-11-03
Posts: 3,669

Re: Microwave ovens for clothes washing

@C.M.:

I guess it was actually the microwave that started fizzing, since dry sponges in a microwave=empty microwave, and if you ever tried to run an empty microwave at full power, you know it sparkles pretty impressively, probably the sparks ignited/burned the sponges....

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#9 2007-01-27 18:49:48

dicktice
Member
From: Nova Scotia, Canada
Registered: 2002-11-01
Posts: 1,764

Re: Microwave ovens for clothes washing

I had a colleague who once put whole eggs in a microwave since he was told it heated them internally. It took him at least 30 minutes to clean the oven after the explosions.

Microwaves are very effective things if treated right but plastics can melt and microwaves treat substances differently depending on the nature of the material. We actualy once considered using them to set concrete for buildings. But found that they caused catastrophic damage and actually threatened health.

That's nothing compared to unpierced chestnuts. Yep, but only once....

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