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

6/17/2019


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, 100% cotton cloths, Doc Cloth, Scotch Brite microfiber, and Handi Wipeswhich do NOT contain silver and are NOT advertised to kill germs. I did two types of experiments to test this. In the first experiment on this page, I put dirty cloths in plastic bags for 24 hours to see how much bacteria grows. In the second experiment on this page, I hung dirty cloths up to dry for 24 hours to see how much bacteria dies. 


Experiment #1--Dirty cloth in a plastic bag.

I did this interesting experiment because a website viewer asked me if she could carry her wet Silvertize cloth around with her in a plastic bag to wipe off her hands throughout the day. My instincts told me that a wet cloth in a plastic bag would grow germs. However, I decided to test it. I tested the Silvertize cloth (a cotton cloth containing 10% silver that is said to kill germs), the Norwex EnviroCloth (a microfiber cloth that contains silver), an e-cloth (microfiber that doesn't contain silver), a thick cotton washcloth, a thin cotton cloth (cut from an undershirt to be a control similar to the Silvertize cloth), a blue Handiwipe, and a yellow Scotch Brite microfiber cloth (no silver).

Silvertize and thin cotton cloth
e-cloth, Norwex, thick cotton
thick cotton, Scotch brite, Handiwipe

First I washed all the cloths on a hot sanitize cycle in my Whirlpool duet HE front loader with Norwex detergent and dried them on a sanitize cycle in the dryer. Then, I rinsed the cloths in warm 90 degree F tap water and blotted them onto agar plates to see how germy they were to start (the BEFORE). Then I rinsed the cloths again in tap water to make sure no agar residue was on the cloths. 

 

Next, I got the cloths mildly germy by wiping hands, cell phones, light switches, door knobs, and computer keyboards. I did my best to get the cloths equally germy BUT there is no way I could guarantee that they were all equally germy to start. (That is why I repeated the experiment several times.) I tried to get the cloths only a little germy and not to get any actual dirt on them. (I did not wipe the floor or any surfaces with actual dirt.) I was not trying to coat the cloths in germs and see how much died. I was trying to put a little bit of germs on there and see how well it multiplied. 


Then I put the cloths in plastic bags and left them on the countertop for 24 hours. (I did not rinse the cloths again after wiping the items before I put them in plastic bags.) 


I also did a control where I boiled a cotton cloth for 10 minutes, rinsed it under tap water, blotted it on the agar plate, and put it in a bag for 24 hours. This controls for any germs that come from my gloves, the bag, the agar plate, the air, or the tap water (which should be very few). 

After 24 hours, I blotted the cloths onto clean agar plates. I put on clean gloves before touching each cloth, of course. The plates were incubated for about 36 hours in my 90 degree F incubator.


Results

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 tested. 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.  

Clean "before" thin cotton and Silvertize cloth
Dirty cotton and Silvertize after sitting in bag for 24 hours
Clean "Before" cloths
Dirty cloths after 24 hours in bag
Before and After
Before and After
Before and After
Before and After
Before and After
There is some variation in my results, likely because of differences in how germy the cloths were in each experiment. As you can see, the cotton cloths, Handi wipe, and Scotch Brite microfiber grew a lot of bacteria in every experiment. The Silvertize cloth hardly grows bacteria in any of the experiments. The Norwex and e-cloth also grows significantly less bacteria than a cotton cloth in all the experiments, but grew more than the Silvertize cloth in most of the experiments. The Norwex contains silver but the ecloth does not contain silver. I'm shocked that the e-cloth e-cloth did so well, and I have no idea why it did. There might be something else special about the Norwex and e-cloth microfibers that inhibit bacterial growth (compared to a cotton cloth) that has nothing to do with the silver. I thought it might be because microfiber is synthetic and bacteria can't live on it and "eat" it quite as well as they can with natural cotton. However, the Scotch Brite microfiber did not do well. It is a mystery. These results confirm the claims that the Silvertize cloth kills germs and that the Norwex does seem to inhibit bacterial growth more than a cotton cloth. We can also learn from this experiment that washing the cloths on a hot sanitize cycle with Norwex detergent and drying on sanitize in the dryer, gets them very clean. 

Cloths with actual dirt in a bag

I repeated this experiment, but this time I wiped the floor with the cloths and got some actual dirt on them. I did not rinse the cloths after wiping the floor. I just looked off them and picked off any crumbs, debris, or dog hair. Then I put them in a bag for only 15 hours this time because I was in a hurry to leave for vacation. I also did not do the clean cloth "before" plates because I did not have enough agar plates. However, I think I have shown enough times already that the cloths washed on a hot sanitize cycle with Norwex detergent and dried on sanitize come out very clean. 
As you can see, with actual dirt present, only the Silvertize cloth seems to still inhibit bacterial growth. I'm not surprised. I would not expect many cloths to be able to penetrate and kill germs in an actual dirt particle, crumb, or dog hair. 


Experiment #2--Hanging dirty cloths up to dry.

10/2/1018

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 on sanitize 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

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. 

Conclusions 

1. Some bacteria will die in any cloth that hangs to dry for 24 hours.

2. Dirty cloths will still have some germs on them even after hanging to dry for 24 hours.

3. Silvertize cloths do inhibit bacterial growth but can still have some live germs on them. I have more Silvertize cloth experiments on this page. 

4. Norwex and e-cloth do not seem to grow bacteria as well as a cotton cloth (in the plastic bag experiments) but can still have a lot of bacteria in them even after hanging dry for 24 hours.

5. A hot sanitize cycle in the washer and dryer with Norwex detergent does a good job killing germs in cloths. 

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. I will be doing more cloth experiments where I use Norwex dish washing liquid to hand wash the cloths before I hang them up to dry and see if that helps keep them less germy. 

Please sign up for my email list if you want to be alerted when I post new results.  Thank you!--Annie Pryor, Ph.D.