Which cleaning cloths kill germs? (Do Norwex cloths kill germs?)

10/2/2018


I have already shown how awesome Norwex and e-cloths are at picking up bacteria. If you haven't seen those results, click here. However, many people have asked me to test whether or not the Norwex Envirocloth kills germs. The Norwex Envirocloth contains silver and the company says that it possesses "self-purification" properties. Some consultants take that to mean that the cloths kill germs, but the Norwex company doesn't technically say that the cloths kill germs. The Silvertize cloth is a cotton cloth that contains 10% silver. The Silvertize company flat out advertises that their cloth kills germs wet or dry. I decided to put them to the test. I also tested the e-cloth, a 100% cotton cloth, Doc Cloth, and Handi Wipeswhich do NOT contain silver and are NOT advertised to kill germs. 

Procedure


My kitchen floor is always good and dirty thanks to my children and our big, dirty, hairy, drooly, loving, handsome, and wonderful dog, Luke. I vacuumed my kitchen floor to get rid of the dog hair before I started each experiment. 


The Norwex, e-cloth, cotton cloth, and Silvertize cloth that I used were washed on a hot sanitize cycle in my Whirlpool Duet washer with Norwex laundry detergent and dried in my dryer before each experiment. I used new Handi wipes and Doc cloths for the experiments. In my other experiments, I determined that washing on the hot sanitize cycle with extra rinse and steam boost with Norwex detergent, get the cloths very clean.  So, I started this experiment with very clean cloths with minimal bacteria.


First, I got all of my clean cloths wet in warm tap water and rung them out. Then I got all of my cloths good and dirty by washing my entire kitchen floor on my hands and knees. I took turns using each cloth. 

Then I used each cloth to wipe out my dirty kitchen sink. 


The cloths were visibly dirty on all sides by the time I was done. 

I blotted each dirty cloth onto an agar plate. This would show us how much bacteria there was to start.



Next I rinsed each cloth under warm 90°F running water for 30 seconds. I really rubbed the cloths with my gloved hands to get them as clean as possible. I rung them out as tightly as possible. 


Then I blotted the rinsed cloths onto agar plates. This would show us how germy they still were after rinsing.
 

Next I hung the cloths on drying racks. This is the drying rack that I invented to dry baby bibs, dish cloths, sports water bottles, and assorted kitchen items. 



I also did a negative control. For this, I boiled a cotton cloth for 10 minutes. (I don't know of any germ that can survive 10 minutes of boiling.) After the cloth was boiled, l let it cool on a clean paper plate. Then, wearing gloves, I rinsed it for 30 seconds under tap water, rung it out, blotted it onto an agar plate, and hung it on the drying rack with the other cloths. 


I put all the drying racks on top of the fridge (so they would be out of the way) for 24 hours. The negative control boiled cotton cloth was there to account for any bacteria that accumulated from hanging there for 24 hours. 

After 24 hours, I wet each cloth with warm 90°F tap water, rung them out, and blotted them onto another agar plate. Yes, of course, I changed gloves between cloths. 



The agar plates were incubated in my warm 90°F incubator for 48-72 hours. 

Results from 8/25/2018


Cotton Cloth
 
Norwex Cloth


E-cloth


Silvertize Cloth


Doc Cloth



Negative Control


As you can see, these cloths started out very germy. The Norwex was probably the most germy. My results show that a 30 second rinse in tap water does not do much to remove bacteria even though the cloths LOOKED significantly cleaner after that rinse. After hanging dry for 24 hours, my results show that there were still a lot of live bacteria on the cloths. The Doc cloth and the Silvertize cloth seemed to have significantly less bacteria in this experiment after hanging dry for 24 hours. All of the cloths had a little less bacteria after the 24 hour mark. However, the 24 hour plates had 24 hours LESS time to grow at the time I took the pictures since they didn't start at the same time. Even taking into account the shorter growing time, it does seem like the Doc cloth and Silvertize cloth had significantly less bacteria. 


Results from 9/8/2018 and 9/25/2018

I repeated this experiment 2 more times, but I made a few changes. I included the Handi Wipe in these experiments. I washed my kitchen floor but tried not to get the cloths as dirty as the first time. I also rinsed the cloths for a full 60 seconds in warm 90°F tap water instead of just 30 seconds.  For the 9/25/2018 experiment, I took the photos separately each after 48 hours of incubation to more accurately compare the amount of bacteria. I also did not blot the dirty "before" cloths onto agar plates because I didn't have enough plates. I just blotted the "dirty, rinsed, before" cloths and the "after hanging for 24 hours" cloths. 

Cotton Cloth




Norwex EnviroCloth




E-cloth



Silvertize Cloth


Doc Cloth



Handi Wipe




Negative controls




Results from 8/31/2018 

For this experiment, I used a Norwex cloth to wipe off the kitchen table and countertops for 3 days. (It was really, really difficult for me to use the same cloth for 3 days.) I rinsed it well after each use and hung it on my drying rack. I did not use it to wipe up raw meat or anything. Just crumbs off the table and countertops. After 3 days, I rinsed it in warm 90 degree water really well for 1 minute and hung it on my drying rack for 24 hours. Then I wet the cloth and blotted it onto an agar plate. As you can see, the cloth still had a lot of bacteria. I recommend using a clean cloth every day. 


What does a clean cloth look like?


It is helpful to know what a normally clean cloth looks like when pressed onto an agar plate. Here are my results when I wash the dirty cloths in my Whirlpool duet HE front loader on the sanitize cycle with (heavy soil) extra rinse and steam boost and sanitize cycle in the dryer with Norwex detergent. 

Dirty used cloths

Cloths after washer and dryer (sanitize cycles)

Here are the clean cloths that have sat around for a few days after washing but haven't been used.

So, you can see that a properly cleaned and sanitized cloth produces very few colonies when pressed onto an agar plate. 

Discussion


From my experiments, it looks like some bacteria will die in any cloth as it sits and hangs to dry for 24 hours. However, a lot of bacteria will still be alive. I can't say for sure if the silver in a Norwex Envirocloth does or does not kill any germs.  All I know is that the cloths still had plenty of bacteria after 24 hours of incubation in my experiments. However, even though I rinsed the cloths for 60 seconds and rubbed them clean the best I could, there could still have been dirt particles on the surface of the cloths. If the germs are suspended in dirt particles slightly away from the silver, would we expect the silver to kill the germs? Maybe not. So, it is difficult to show whether or not the silver in the cloth really kills germs. However, I have shown that a used Norwex cloth (and most any cloth) is most likely NOT germ-free after hanging up to dry for 24 hours. You might get better results if you scrub the Norwex with dish soap, rinse it in hot water, and then hang them up to dry, but I have not tested that. It does look like the Silvertize cloth has some germ-killing power.

From my results, it seems like the Silvertize Cloth (which is 10% silver) might actually have some germ-killing power. The Silvertize cloth is a smaller and more delicate cloth than the others. It is advertised for wiping hands, cell phones, and electronics. It is not for "mopping the floor" and "scouring the sink" like I did with it. The Silvertize cloth is even advertised to work DRY so you can carry it with you in your purse or pocket. I will be doing more experiments with the Silvertize cloth to see what it can really do on hands, cell phones, and keyboards wet and dry. So, stay tuned. Please sign up for my email list if you want to be alerted when new results are posted. 

Another thing I noticed from these experiments is that the Norwex, E-cloth, and Silvertize cloth rinsed off SO MUCH EASIER than the cotton cloth, Doc cloth, or Handi Wipe. The dirt, lint, and dog hair just rolled off the Norwex, e-cloth, and Silvertize cloths. However, it was painful to try to rinse dog hair off the cotton cloth, Doc cloth, and Handi Wipe. I had to pick each dog hair out of those cloths individually. There are probably other weaves of cotton cloth that are easier to rinse off. The one I used was a bath washcloth and was very difficult to rinse. 

My previous experiments have already shown that the Norwex Envirocloth and e-cloth are really awesome at picking up germs. I just recommend using a clean cloth every day and washing it on a hot sanitize cycle between uses (or boiling) instead of using the same cloth for multiple days. I wish I could tell you that all you need to do is buy my drying rack and hang your cloths up to dry for 24 hours, and they would be all clean. But I can't have someone catching salmonella because I want to sell drying racks. It is a good idea to hang them up between uses during the day instead of leaving them balled up at the bottom of the sink to grow even more germs, though. 

Please sign up for my email list if you want to be alerted when I post new results. Also, please use my Amazon affiliate links, like this one, when you shop on Amazon so I can earn money to buy agar plates and do more experiments. Thank you!--Annie Pryor, Ph.D.