Face shield bleach disinfection

  • #1
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Faceshield or respirators are getting to be as common as masks in public.

What kind of bleach in basin can theoretically kill the covid virus? What should be the concentration of bleach and now does it kill it?
 

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  • #2
jim mcnamara
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Commercially available bleach in the US is supposed to label NaOCl content. Bleach degrades sitting on the shelf over time as well. You want fresh bleach with 5% or greater NaOCl content. Restaurant supply stores routinely stock 8% bleach. And the stock turns over a lot. It is intended as a disinfectant.

Short version of CDC https://www.cdc.gov/disasters/bleach.html:

Dilute the bleach 1 part in ten -- i.e., 9 cups water, 1 cup bleach. Leave the bleach on the already cleaned surface to disinfect for at least 30 seconds. The label will have directions. For example, after you dilute the bleach it will lose potency in a few days.

It eats clothing....

It is not "theoretical" - this stuff will disinfect as long as all parts of an item are in full contact with the bleach solution for the correct time. So. This stuff will ruin clothing, bleach concentration for normal laundry is much less. :frown:
 
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  • #3
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Commercially available bleach in the US is supposed to label NaOCl content. Bleach degrades sitting on the shelf over time as well. You want fresh bleach with 5% or greater NaOCl content. Restaurant supply stores routinely stock 8% bleach. And the stock turns over a lot. It is intended as a disinfectant.

Short version of CDC https://www.cdc.gov/disasters/bleach.html:

Dilute the bleach 1 part in ten -- i.e., 9 cups water, 1 cup bleach. Leave the bleach on the already cleaned surface to disinfect for at least 30 seconds. The label will have directions. For example, after you dilute the bleach it will lose potency in a few days.

It eats clothing....

It is not "theoretical" - this stuff will disinfect as long as all parts of an item are in full contact with the bleach solution for the correct time. So. This stuff will ruin clothing, bleach concentration for normal laundry is much less. :frown:
How does the bleach destroy the virus? By defragmenting the dna? Can detergent do that too?
 
  • #4
BillTre
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How does the bleach destroy the virus? By defragmenting the dna? Can detergent do that too?
It oxidizes organic compounds (proteins, DNA, RNA, etc.). They won't work right after that. That's why it eats textiles.

The stronger the bleach, the less time it takes to treat things.
If the thing you want to sterilize has metal parts, you might want to be careful bleaching them. they might get oxidized (similar to rusting).
 
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  • #5
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It oxidizes organic compounds (proteins, DNA, RNA, etc.). They won't work right after that. That's why it eats textiles.

The stronger the bleach, the less time it takes to treat things.
If the thing you want to sterilize has metal parts, you might want to be careful bleaching them. they might get oxidized (similar to rusting).
What else can do that besides bleach and possibly alcohol?
 
  • #6
BillTre
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What else can do that besides bleach and possibly alcohol?
Alcohol won't oxidize. It will denature proteins (they take an incorrect shape and won't work) and destroy membranes.
Hydrogen peroxide (H2O2), on the other hand, will oxidize chemicals.
 
  • #7
256bits
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Maybe not part of the original OP, but since other than bleach was mentioned,

Do the cleaners made at home, or store bought and labelled as "organic", using "active " ingredients such as citric acid, vinegar, baking soda, ( or even ammonia ), etc have any benefit for viral and bacterial decontamination of surfaces other than maybe removing and washing them away with the liquid?
 
  • #8
Borek
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Do the cleaners made at home, or store bought and labelled as "organic", using "active " ingredients such as citric acid, vinegar, baking soda, ( or even ammonia ), etc have any benefit for viral and bacterial decontamination of surfaces other than maybe removing and washing them away with the liquid?
To some extent - yes, they all have pH that is far from neutral and that is often enough to denature proteins (not always - enzymes used for digestion in stomach are actually activated by a very low pH which doesn't denature them at all). No idea how effective these cleaner are. If I had to choose between a - say - vinegar based cleaner with no surfactants and just soap, I would go for the latter, as the denaturation process can be reversible (doesn't have to be, a lot depends on the protein and exact pH), and soap should just destroy the virus breaking it into smaller chunks.

I am not sure this line of thinking is a correct one though, just a (more or less) educated guess.
 
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  • #9
jim mcnamara
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The Covid 19 pathogen is a virus. It has RNA rather than DNA in the core. The virus core is inside a lipid layer. Soap or detergent breaks that lipid layer down.

You can use denatured ethyl alcohol or iso-propanol as disinfectants. Avoid any alcohol less than ~70%. You can disinfect your hands with it. Some clothing dyes get washed out by alcohol.

Bleach is not a good choice for hand washing.
 
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  • #10
atyy
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What else can do that besides bleach and possibly alcohol?
Just use soap and water. The main action of soap and water is to wash the virus away. The soap will help water to wash oil away, so that there won't be virus stuck around in oil. You can wash it the same way as you wash your hands. Spend a good amount of time scrubbing all surfaces such that there is plenty of lather, then rinse thoroughly with water.

Soap and water also disrupts the lipid membrane of the virus. This takes longer, you can leave the soap and water on for 30 minutes if you like if you depend on this as the primary mechanism. However, if you use this as the secondary mechanism (with washing virus away as the primary mechanism), it is just fine to give it a thorough wash with soap and water.

Kate Winslet - Wash your hands like your life depends on it.
How soap absolutely annihilates the coronavirus
Why Soap Works
 
  • #11
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... Short version of CDC https://www.cdc.gov/disasters/bleach.html:

Dilute the bleach 1 part in ten -- i.e., 9 cups water, 1 cup bleach. Leave the bleach on the already cleaned surface to disinfect for at least 30 seconds.
Do you believe that the lower concentrations recommended by CDC for coronavirus on household hard surfaces (as low as 2%) is still effective?
What is the chemical reason for the recommendation against mixing bleach with detergent, ammonia, etc.?

Copied from
https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/disinfecting-your-home.html

"To make a bleach solution, mix 5 tablespoons (1/3rd cup) bleach per gallon of room temperature water."
 
  • #12
Borek
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Do you believe that the lower concentrations recommended by CDC for coronavirus on household hard surfaces (as low as 2%) is still effective?
Do you have any reason to suppose CDC recommendations are wrong? My bet is whoever prepared their recommendations knows more than we, random folks of the internet.

What is the chemical reason for the recommendation against mixing bleach with detergent, ammonia, etc.?
Bleach tends to react with many things. First, it renders the bleach useless (it is spent on reacting with other components of the mixture instead of disinfecting the surface it is later applied to), second, products can be dangerous or at least irritating.
 
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  • #13
jim mcnamara
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There are different versions of bleach solution used in medicine and veterinary care.

Laundry bleach and food service disinfectants are high pH, usually with NaOH added to raise the pH. Ideal for destroying pathogens.

For wound irrigation NaOCl solutions are more dilute and pH is close to 7.0 - so-called Farmer's solution -- because it is often used in caring for animal wounds. Works fine on people wounds, too.
 
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  • #14
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Do you have any reason to suppose CDC recommendations are wrong? My bet is whoever prepared their recommendations knows more than we, random folks of the internet.



Bleach tends to react with many things. First, it renders the bleach useless (it is spent on reacting with other components of the mixture instead of disinfecting the surface it is later applied to), second, products can be dangerous or at least irritating.
How long can the silicone, polycarbonate or rubber be damaged if soaked in bleach?

I removed the P100 cartridge and spectacles before washing with just soap and water.

But with the virus scorging the planet sparing no land. Then have to take more stringent disinfection routine but im not sure the uv lamp can kill the pathogen in the following hence thinking of soaking in bleach.

20200725_100920.jpg
 
  • #15
Borek
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How long can the silicone, polycarbonate or rubber be damaged if soaked in bleach?
The only viable answer is: you have to check experimentally. Way too many factors. Materials you listed are not well defined, their properties will differ depending on the make, maker, quality, surface finishing and so on.
 
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  • #16
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Do you have any reason to suppose CDC recommendations are wrong? My bet is whoever prepared their recommendations knows more than we, random folks of the internet.
...
Just asking about the reason behind the recommendation for stronger concentration in post #2 ("Dilute the bleach 1 part in ten") versus the 2% recommended by CDC for coronavirus on household hard surfaces.
 
  • #17
atyy
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How long can the silicone, polycarbonate or rubber be damaged if soaked in bleach?

I removed the P100 cartridge and spectacles before washing with just soap and water.

But with the virus scorging the planet sparing no land. Then have to take more stringent disinfection routine but im not sure the uv lamp can kill the pathogen in the following hence thinking of soaking in bleach.
You really can just use soap and water. Washing several times with soap and water should be fine, same as you would do with your hands. Otherwise, washing your hands is not going to work. If you are worried, then you can leave it soaking in soap and water for 30 minutes, before washing it several times with soap and water. The important thing is to scrub all surfaces such that it is well covered by lather, then wash it off.

For example, https://www.ecdc.europa.eu/sites/de...mental-cleaning-non-healthcare-facilities.pdf states "Tests carried out using SARS-CoV showed that sodium hypochlorite is effective at a concentration of 0.05 and 0.1% after five minutes, when it is mixed to a solution containing SARS-CoV [5]. Similar results were obtained using household detergents containing sodium lauryl ether sulphate, alkyl polyglycosides and coco-fatty acid diethanolamide [5]."

Sodium lauryl ether sulfate is basically soap. The above was reported for SARS, not the COVID-19 virus, but we expect it to work the same way, because coronaviruses have a lipid envelope, which should be disrupted by soap and water.
 
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  • #18
jim mcnamara
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You are correct. The CDC statement is 2%. Not .05% NaOCl that you get from Brand X laundry bleach diluted as I mentioned. Thanks.

@atyy linked to my source for for the dilution. Thank you.
 
  • #19
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Both chlorine and UV light tend to trash organic materials.

If it was mine, and for some reason I was afraid to read the owner's manual, I'd stick with soap/water - plain old laundry soap is pretty good, with the caveat that it doesn't contain the (re)moisturizers that hand-soap does.
 
  • #20
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Both chlorine and UV light tend to trash organic materials.
What organic materials exist in non living matter?

If it was mine, and for some reason I was afraid to read the owner's manual, I'd stick with soap/water - plain old laundry soap is pretty good, with the caveat that it doesn't contain the (re)moisturizers that hand-soap does.
 
  • #21
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What organic materials exist in non living matter?
The rubber on the facemask, for instance.
 
  • #22
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The rubber on the facemask, for instance.
3M seems to authorize it. I saw the link at comments in


"Possible disinfection methods: • Sodium hypochlorite solution (at a free chlorine concentration of 5,000 ppm) with 1-minute contact time • 70% Isopropanol solution with 1-minute contact time"
 
  • #23
Buzz Bloom
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Faceshield or respirators are getting to be as common as masks in public.
What kind of bleach in basin can theoretically kill the covid virus? What should be the concentration of bleach and now does it kill it?
Hi Secan:

I think you may be overlooking the fact that a very large fraction of masks are made of paper. This "fact" is based on what I wear and what I see on the faces of other people when I take an exercise walk outdoors.

Regards,
Buzz
 
  • #24
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Hi Secan:

I think you may be overlooking the fact that a very large fraction of masks are made of paper. This "fact" is based on what I wear and what I see on the faces of other people when I take an exercise walk outdoors.

Regards,
Buzz
Made of paper? I was talking about faceshield. Its made mostly of plastic. The visor is made of acetate plastic.

20200728_085351.jpg


In some countries. People are required to wear them.

Its so hassle to wash them with soap and water everytime you use them. So its more convenient to put them in either uv sterilizer cabinet or soak in bleach.

Is acetate plastic organic?
 
  • #25
109
5
Commercially available bleach in the US is supposed to label NaOCl content. Bleach degrades sitting on the shelf over time as well. You want fresh bleach with 5% or greater NaOCl content. Restaurant supply stores routinely stock 8% bleach. And the stock turns over a lot. It is intended as a disinfectant.

Short version of CDC https://www.cdc.gov/disasters/bleach.html:

Dilute the bleach 1 part in ten -- i.e., 9 cups water, 1 cup bleach. Leave the bleach on the already cleaned surface to disinfect for at least 30 seconds. The label will have directions. For example, after you dilute the bleach it will lose potency in a few days.

It eats clothing....

It is not "theoretical" - this stuff will disinfect as long as all parts of an item are in full contact with the bleach solution for the correct time. So. This stuff will ruin clothing, bleach concentration for normal laundry is much less. :frown:
The reason i want to try bleach is to avoid using soap and water and hand contact. Sometimes i thought the virus from the visor could be blown away during hand washing if there is strong wind from say an electric fan. Can it? Or virus sticking to my unwash skin.

Second, do you really need to wear gloves and goggles (or eye protection) just to use bleach. If it does it will defeat the purpose of convenience.

If so. Ill buy multiple faceshields or respirator and just keep the used ones inside a plastic bag for 5 days. The virus will die automatically? I do this lately. But what is the reason the virus will just die out since it doesnt require any food at all?
 

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