Silvertize Cloth Independent Testing
1/16/2019
The Silvertize Cloth is an exciting new cloth containing 10% silver that is supposed to kill 99.9% of bacteria, viruses, and fungi. The company claims that it kills germs whether the cloth is wet or dry. They say that it is great for hands, phones, electronics, and many other things. If you don't want to read all of this page, click here for the spoiler results summary. The cloth is made of cotton which the company says is critical for the production of the germ-killing silver ions within the cloth. They say that artificial fibers (like microfiber) don't produce silver ions as well.
The Silvertize company asked me to test their cloths and sent me a few free cloths to test. Here is the packaging mine came in. The company has since updated their packaging.
I tested the Silvertize cloth to see if it kills germs and how well it removes germs from surfaces. I did not test it on hands. Skin has so much natural bacteria that it is hard to see how much is removed.
Does the Silvertize Cloth kill germs?
I tested several cloths for the ability to kill germs, including the Norwex cloth, and the Silvertize cloth is the only one that appears like it might actually kill germs. You can see all of the results and the complete experiments on this page. Here is a brief summary.
I washed my entire kitchen floor with cloths, including the Silvertize cloth, and got the cloths very, very, dirty. Then, I blotted the dirty cloths on agar plates as the "before".
Then I rinsed the cloths in warm 90°F water for 30 seconds and blotted them again. Next, I hung them up to dry for 24 hours. After 24 hours, I wet the cloths in tap water and blotted them onto agar plates again. The agar plates were incubated in my warm 90°F incubator for 48 hours.
In case you are new to looking at agar plates, 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.
Norwex Cloth Results
Silvertize Cloth Results
As you can see, a lot of bacteria died in the Silvertize Cloth compared to the other cloths. So, it does seem like the cloth might really be killing germs. Please note that when you are using the Silvertize cloth to wipe off phones and keyboards, it is not going to get as filthy as I got it for this experiment. The Silvertize cloth might have an even easier time killing germs when it isn't as saturated with dirt as it was in this experiment.
Please read my "Which cleaning cloths kill germs" page if you want more details from this experiment.
Do germs grow on a wet Silvertize cloth sitting in a plastic bag all day?
One of my viewers wrote to me and said she would like to carry around a wet Silvertize cloth in a plastic bag all day to wipe off her hands throughout the day. My instincts told me that carrying any wet cloth in a bag would not be a good idea because germs would grow. However, I decided to test it for her.
First, I cut a piece of plain 100% cotton white undershirt about the size of a Silvetize cloth. Since the Silvertize cloth is cotton with 10% silver, this would be my cotton cloth control with no silver.
I rinsed both of the cloths in warm 90 degree F tap water and blotted them on agar plates so I could see how germy they were to start. After blotting on the agar plates, I rinsed the cloths again to get rid of any traces of agar on the cloths.
Next I wiped off my hands, cell phones, light switches, door knobs, keyboard and a few other things with the cloths. I tried not to get any actual dirt on the cloths. I did not want them to be too germy to start.
Then I put the cloths into plastic bags and let them sit on the countertop for 24 hours.
After 24 hours, I blotted the cloths onto agar plates and incubated them in my 90 degree F incubator for 24 hours.
Results
Clean Cotton and Silvertize cloths "before"
Dirty Cotton and Silvertize cloths after sitting in bag for 24 hours.
The results were amazing! The Silvertize had hardly any bacteria on it compared to the plain cotton cloth! I repeated this experiment several more times. In the repeats, I included a boiled cotton cloth control. (I boiled a cotton cloth for 10 minutes, rinsed it under tap water, blotted it on an agar plate, and put it in a plastic bag for 24 hours just like the rest of the cloths.) This control should not have any germs. I also included a thicker cotton cloth in some of the experiments to compare. Here are more results.
For every experiment that I do, I always have a tap water control where I swab some tap water and rub it onto a plate. This negative control never grows germs. So, I won't show you every single tap water control that I do.
From these results, I feel extremely confident that the Silvertize cloth inhibits bacterial growth. There is a huge difference between a plain cotton cloth and the Silvertize cloth. This doesn't mean that the Silvetize cloth will always be perfectly sterile. However, it grows far less bacteria than a plain cotton cloth. The Silvertize company claims that it also kills viruses, but I can't do any tests with viruses. So, if you want to carry a wet one in a bag all day to wipe off your hands, I don't see any reason not to. If you would like to purchase Silvertize cloths, you can do so here.
How well does the wet Silvertize Cloth wipe off germs?
No matter how good a cloth kills germs, it won't kill them if it doesn't wipe them off surfaces, right? In these experiments, I swabbed cell phones and a computer keyboard before and after wiping them for 30 seconds with a wet Silvertize cloth. I wet the cloth in warm 90°F tap water and thoroughly rung it out. Then I wiped the phone (or keyboard) off for 30 seconds. I did the best possible job.
Then I swabbed the phone all over (except for the edges that I was holding) and rubbed the swab onto an agar plate. The plates were incubated for 48 hours in my warm 90°F incubator.
RESULTS
BEFORE AFTER
The wet Silvertize cloth did a great job removing germs from these items. I also tested how well the Silvertize cloth removed germs from a dirty section of my kitchen floor. I swabbed the floor before and after wiping with the Silvertize cloth.
Again, the wet Silvertize cloth does a good job picking up dirt and germs. It is NOT as good as a Norwex cloth at picking up dirt and germs off the floor in my experiments, though. This isn't surprising. The Silvertize cloth is a thinner, smooth cloth and is meant for more delicate jobs. It is most likely not meant for washing the kitchen floor.
How well does a DRY Silvertize Cloth wipe off germs?
The Silvertize company also claims that the cloth kills germs even when dry. For this experiment, I wiped the phones with a dry Silvertize cloth all over for 30 seconds. I swabbed the phones before and after and rubbed the swabs onto agar plates. The plates were incubated for 48 hours in my warm 90°F incubator.
RESULTS
BEFORE AFTER
It is hard to imagine that any dry cloth would clean as well as a wet cloth. So, I'm not surprised that the dry Silvertize cloth does not get the germs off phones as well as the wet cloth. The company advertises that the cloth still kills germs even when dry. I am not contradicting that claim. The cloth may still kill germs even when dry. However, my results show that the cloth is unlikely to get germs off a surface as well when it is dry compared to when it is wet. It may still kill whatever germs it did pick up when dry.
Conclusion
The Silvertize Cloth does seem to have germ-killing capabilities. It grows far less bacteria than a plain cotton cloth. In my experiments, it removes germs better when it is wet than when it is dry. I did not determine how fast the Silvertize cloth kills germs. I also can't guarantee that the Silvertize cloth will kill every type of germ. I like the Silvertize cloth because I know it is safe for my electronics and won't scratch a screen. If you would like to try a Silvertize Cloth, you can order here. --Annie Pryor, Ph.D.