My Microwave Washing Sponge Experiment

Last night on my way home from work, I heard WCBS radio mentioned that the best way to kill bacteria in kitchen sponge isn’t wash it in dishwasher, but put in microwave oven for 2 minute at full power. That sounded a fine and simple idea to me as we only use hot water and dishwashing liquid to wash our sponges, those Scotch-Brite scrub sponge we bought from Costco.

When I got home, I tried this new method to see how it works. The sponge I put in the microwave oven was wet since I felt it won’t be a good idea to put a dry sponge in the microwave. So I washed it and put it in a bowl. After only about forty seconds, the oven was full of steam and I stopped it. The sponge was fine, except that it was very hot. Then I put it back and let it finish the time. But I smelled something was burning and had to stop the microwave with a few seconds left on the clock. The sponge side was totally dried out. On the blue fiber side, however, there was a small black hole.

This apparently isn’t a small story as LifeHacker.com also mentioned it today and there’s a story on CNN.com tonight reporting several incidents when people put dry sponge in the microwave oven, trying to follow the recommendation to kill sponge germs. University of Florida, which recommended this method, issued the following advisory:

To guard against the risk of fire, people who wish to sterilize their sponges at home must ensure the sponge is completely wet. Two minutes of microwaving is sufficient for most sterilization. Sponges should also have no metallic content. Last, people should be careful when removing the sponge from the microwave as it will be hot.

My sponge was wet but still got ruined. Later what I found the best way to sterilize washing sponge is to just submerge it in a shallow container and put it in the microwave for 2 minutes at highest power. No more burned sponge :)

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2 Responses to “My Microwave Washing Sponge Experiment”

  1. TJP |  Jan 25, 2007 at 7:54 am

    Hmm…maybe submerging the sponge in alcohol would kill the bacteria. I don’t think placing a flammable object in the microwave is such a good idea.

  2. paigu |  Jan 25, 2007 at 4:46 pm

    I’ve actually done this before, but for the purpose of cleaning the microwave since, as you noticed, a lot of steam is produced. I’d stick with using medium to med-hi power and no more than 2 minutes at a time.