How to Sterilize Cotton in Microwave
What to know

How to Sterilize Cotton in Microwave

Ideally, the best way to sterilize cotton involves using the autoclave. This device specifically sterilizes lab equipment and waste as used in laboratory and medical settings. Sterilization to a layman involves boiling anything in hot water for an extended period of time, usually glass flasks or kitchen utensils.

When sterilizing cotton, it involves autoclaving it at 273.2°F to 278.6°F (134°C to 137°C) since that’s the standard method used in hospitals when sterilizing cotton wool balls and cotton gauze pads. Cotton has an ignition temperature of 752°F (400°C) so scorching remains low risk.

How to Sterilize Cotton in Microwave

100 percent cotton—along with wool, hemp, and, linen—has microwave-safe properties. It’s unlikely to catch fire and melt in the microwave because a microwave is unlikely to reach cotton’s ignition temperature of 752°F.

You can safely microwave almost all-natural fibers. So to sterilize cotton, you should heat it up while dampened for about 30 seconds to 2 minutes or until you reach 250°F (120°C). The same technique allows you to make steam with cotton inside your microwave. It doubles as a sterilization method.

Leave it there simmering in hot steaminess to really kill all potential bacterial development then take it out after 5 to 10 minutes.

 You may also like this video:

How to Sterilize Cotton in Autoclave

As mentioned above, you should sterilize cotton wool balls the same way hospitals do by autoclaving them at 273.2°F to 278.6°F. You need reach at least 752°F in order to leave your cotton balls scorched or set aflame by the autoclave (an unlikely scenario).

We recommend you put those cotton balls in an autoclave paper bag then activate the dry (solid autoclave cycle. You can also autoclave some forceps—like those used in animal surgery—in a metal box on the same setting.

After the autoclave process ends, put everything inside a hot desiccation chamber at 140°F (60°C) for at least 3 hours.  Then the cotton balls should be fully sterilized (even more so than the microwave method).

How Do You Sterilize Items with the Microwave?

Items like cotton balls, gauzes, mason jars, and plates end up sterilizes when you bring them at a high-enough temperature to kill viruses and bacteria while holding onto them in place long enough for the sterilization process to work.

Due to this, microwave ovens might prove useful in doing more than just zapping leftovers for dinner. You can use them to sterilize microwave-safe items in your house to protect your family from germs or even the spread of COVID-19.

You should, in particular, start microwaving your plastic scrubbers and kitchen sponges. They tend to be nasty carriers of viruses and bacteria that cause all sorts of food-borne illnesses. Rapidly sterilize them for your own family’s safety.

Read more: 22 Surprising Things Your Microwave Can Do

A Powerful Weapon Against Food Poisoning and Diseases

Because 90 percent or so of Americans own microwaves in their kitchens instead of autoclaves—mostly a medical item resembling a microwave or standard oven—you can use that device as your weapon against kitchen and medical supply contamination.

For cotton swabs, gauze, or even cloth you use to handle pans and bowls, you can sterilize or approximately stave off bacterial spread by heating them up quickly and efficiently with boiled water inside your microwave at a given temperature.

This way, you can prevent salmonella, E. Coli, or other germs and microorganisms to spread on your food and make your daily sustenance become outright poisonous.

You Can Knock out Most Bacteria in Two Minutes

You can knock out most bacteria in two minutes inside the microwave at full power and with boiling water present. You can put your scrubbers and sponges at the dishwasher in order to induce some measure of sterilization, but the microwave works more like an autoclave compared to your washer.

Take note that in terms of medical sterilization requirements, the autoclave remains your best bet but most households have no access to such a device. Some might have not ever heard of such a device at that. The autoclave has been specifically designed for sterilization while the microwave isn’t.

See more: Does Microwave Kill Bacteria in Water?

An Approximation of an Autoclave Performance

The microwave can approximate (but not duplicate) the decontamination and sterilization capabilities of the medical autoclave that goes beyond just cleaning your jars and dishes with hot water. After all, it’s an oven that can reach high temperatures and similarly high speeds.

Take note that this is in accordance to the research of anesthesiology professors, biomedical engineering doctoral students, and wastewater microbiology experts.

The Findings of Their Research in Microwave Sterilization

The researchers doing research on the effectiveness of microwaves in inducing effective sterilization of scrub pads and sponges used varying lengths of time to microwave them while wet and after use. They then wrung them out to determine the microbial load of the water performed on each test.

They soaked the sponges and scrubbing pads in raw wastewater containing a Petri dish of nastiness such as fecal bacteria, bacterial spores such as Bacillus spores, protozoan parasites, and viruses.

Two Minutes to Reach 278.6°F

After comparing their findings from the water from pads and sponges not placed in the microwave, they were able to conclude a significant difference. Since sterilization occurs between 273.2°F to 278.6°F, it’s safe to say that in about 2 minutes, microwaves can reach that hotness.

You can also heat up the sponge in 30-second increments and let the heat built up gradually then let the sponge (or cotton ball) stand inside the oven in all that hot steam until all microbes end up dead. This should save your household in medical bills from disease and food poisoning.

You can especially benefit from this pseudo or partial sterilization process when it comes to preventing the spread of COVID-19 in your household since it really levels up your sanitation safeguards.

The Nitty-Gritty

You can sterilize items in the microwave as long as they’re microwave-safe materials. You can’t sterilize metal with the microwave, stick to the stove for boiling or the autoclave for that. Material can be microwave-sterilized if it doesn’t melt from prolonged microwave exposure.

If you were to microwave clothing for sterilization, you risk an exploding microwave due to arcing from its metal zippers or melting from its plastic zippers. You could even damage the device if you’re not careful!


  1. Researchers: Microwave oven can sterilize sponges, scrub pads“,, January 22, 2007
  2. Can I use a microwave to sterilize clothes in place of an autoclave?“,, November 27, 2019

Through the years, the microwave oven has become a standard appliance for all homes. It is safe to say that there is no home without a microwave oven. If you are looking for a microwave oven that best fits your needs, You find the right website.

Leave a Reply

Your email address will not be published. Required fields are marked *