What is the best way to clean a face mask?

10/7/2020

A clean face mask that covers your nose and mouth will catch the spit that flies out of your mouth when you talk. It will also stop someone else's spit from getting directly in/on your nose and mouth. It will not filter all of the air that breath in and out. But decreasing the amount of spit flying around during a pandemic may help reduce the number of sick people. We hope. However, masks get very germy. They get germs from your skin, mouth, and nose. They also get germs from the your fingers, since almost everyone touches and adjusts their mask constantly. So germs from public surfaces that you touch, inevitably end up on your mask. The warm moist environment of the mask is perfect for growing bacteria and fungus. 

Problems caused by wearing masks

Maskne--acne caused by wearing masks. The acne is likely caused by the mask keeping your warm and moist for hours. The friction from the mask might also contribute. Using a detergent or soap to wash the mask that irritates your skin might contribute. However, a bacteria-laden mask could also be a factor. Wear a clean mask!

Skin infections-- can occur in the warm, moist areas covered by the mask. The warm, moist mask environment is perfect for growing bacteria and fungus! This particular picture is a friend of mine who got a staph infection from wearing her mask.

Illness--If a dangerous germ (norovirus or strep, for example) that you accidentally put on your mask (usually from your dirty fingers) gets into your nose or mouth, you may get sick.

How germy are masks?

When I blot face masks that have been worn all day onto an agar plate, lots of bacteria and fungus grow. I always blot both the inside and outside of the mask on the agar plates.

However, when I blot a new disposable mask straight from that package on an agar plate, the results vary from a tiny bit growing, to nothing growing. 

About Agar Plates

In case you are new to looking at agar plates, let me explain. The whitish/yellowish dots on the plates are colonies (or piles) of millions of bacteria. Not all types of bacteria can grow on these agar plates. Viruses can NOT grow on these agar plates. Yeast, mold, and fungus CAN also grow on these plates. In general, the more colonies that grow on the plate, the more germs there were on the surface that was swabbed. However, a clean agar plate does not necessarily mean that no germs whatsoever were present on the surface because not everything can grow on an agar plate.

Tap Water Negative Control

In all of my experiments, I put a small amount of tap water onto the dry masks before I blot them onto the agar plates. This dampness helps the germs to transfer from the mask to the agar. In some experiments, I use tap water to wash the masks either by hand or in the washer. I always do a negative control test to make sure that no germs grow from the water. 

I rarely ever have any bacteria grow on my negative control tap water plate. 

What is the best way to clean and kill germs in your face mask?

I have tested several methods for cleaning and killing germs in face masks. Keep reading to see which worked the best. 

Hand Washing Masks

I washed several face masks by hand to see how clean they got. First, I blotted the worn mask onto an agar plate for the "before". I always blot both the inside and the outside of the mask onto the agar plate. 

Then I wet them under warm 100 degree F tap water. I put a little Dawn dish soap in each side of the mask and scrubbed and lathered for 1 minute.

Then I rinsed the mask under warm 100 degree F tap water for 1 minute, and blotted it onto another agar plate. 

Hand Washing Results

As you can see, the hand washed masks still had a lot of germs. I got similar results when I tested hand washing dish cloths so this is not surprising. You can see the dish cloth results here. If you do decide to hand wash your masks, use the hottest water you can handle. 

Negative Control

In order to be sure that the tap water, dish soap, and process of hand washing didn't introduce germs, I tested washing a mask that had been boiled.  So it was perfectly clean to start. I washed the boiled mask with Dawn dish soap just like I did the other masks. Then I blotted it on an agar plate.

As you can see, the process of hand washing with soap did not introduce any significant amount of germs. Nothing grew on that plate.

Machine Washing Masks

It is convenient to throw masks in the laundry, but I wanted to test how well the germs came out in the laundry. I washed them in a mesh bag, so they wouldn't get tangled up. 

To do these experiments, I used masks that had been worn for 1 day (6 to 8 hours). I blotted the masks onto agar plates before washing, after going through the washer, and after going through the dryer. I incubated the plates in my warm 90 degree F incubator for about 48 hours.

Cold Wash

I also tested washing on hot in my Speed Queen which was about 130 degrees F. 

I also tested washing the masks on the Sanitize Cycle in my Whirlpool Duet HE front loader. 

As you can see washing the masks in the a hot washer and dryer, significantly decrease the number of germs. But it isn't perfectly sterile afterward. These results are consistent with the many, many laundry experiments that I have done. 

PhoneSoap UV-light Box for Masks

I have already tested the PhoneSoap UV-light box, and showed that it does indeed kill some germs. You can see those experiments here. Since it was about the right size for a disposable mask, I thought I would test its ability to kill germs in/on a mask. 

I blotted a disposable mask onto an agar plate both before and after a 10-minute session in the PhoneSoap.

PhoneSoap Results

As you can see, 10 minutes in the PhoneSoap does kill some germs, but it doesn't kill everything. It is unlikely that the UV light penetrates all the folds in the masks. 

UV-light wand for masks

I also tested a Verilux CleanWave Portable Sanitizing Travel UV-light wand for its ability to kill germs in/on a mask. To do these experiments, I blotted the masks on agar plates both before and after passing the UV-light wand over them. I tested cloth and disposable masks.

I moved the UV-light wand slowly over the mask for 2 minutes each on each side. The wand was 1/2 inch or less above the mask.

UV-light wand results

Please note that I did two "before" plates in each of these experiments. I blotted the inside of the mask on one agar plate and the outside of the mask on the other agar plate. I was curious if more germs were on the inside or outside. 

Well, 2-minutes with the UV-light wand did not do very well killing germs on the masks. It was also annoying to stand there and move that wand. So, I don't think the UV-light wand is the solution for masks. It did seem that the outside of the masks might have been germier than the insides, though. 

For a negative control, I passed the UV-light wand over a new mask for 2 minutes on each side and blotted it onto an agar plate. It was very clean. 

Boiling Masks

I also tested how well boiling kills germs in the masks. I blotted the masks on agar plates both before and after boiling for 5 minutes. Some of these results show the hand washing results, too. (For some experiments, I washed the masks by hand, blotted them on agar plates, and then boiled them.) Some of these results also show boiling for 2 minutes and 10 minutes.

As you can see, boiling does a fabulous job killing germs! These results are consistent with all of the experiments that I did to test the best way to kill germs in/on a Norwex Cloth. 

Boiling can shrink cloth masks if you aren't careful! After boiling, let them cool a minute until you can touch them. Then gently stretch them out and tug on them to make them bigger. Then hang them up to dry. Mine have not shrunk too much by doing this. 

Boiling Disposable Masks

I felt silly even trying this. Surely, a disposable mask would fall apart when it got wet, right? I think the light-weight disposable masks more comfortable to wear than cloth masks, but I don't like throwing them out every day. They are expensive AND just make more trash. So, I tested boiling them for 5 minutes. I blotted them on agar plates before and after boiling. 

To my astonishment, they came out very nicely! And the boiling killed the germs! Boiling will shrink the masks, though. Try stretching them out really good after you boil them. Let them cool until you can touch them, then stretch them out, then hang them up to dry. 

I'm sure the disposable mask companies would tell you that boiling them is a bad idea, and that it will harm the integrity of the mask. So, boil them at your own risk. 

Do masks acquire more germs after hanging to dry? 

You might be wondering if these clean boiled masks acquire more germs while hanging up to dry. Do they just get germy all over again from the air? So, I tested this. I tested masks that I had boiled and hung up to dry for 24 hours and 3 days.

Boiled mask hung up to dry for 24 hours.

Boiled masks hung up to dry for 3 days. 

As you can see, after boiling, the masks stay pretty clean when you hang them up to dry. 

Conclusions

Well, I'm going to be boiling my masks and hanging them up to dry from now on! If you would like to order one of the drying racks that I invented which are great for sports water bottles, baby bibs, dish towels, food-storage bags, and MASKS, please visit my website www.mommygenius.com. I'll also be doing lots more mask experiments, so please check back often. You are also welcome to like my facebook page and sign up for my email list.