Hand Washing Tip

[ProfessorGAC]

This is based upon something I saw here about hand washing, purportedly for Johns-Hopkins, though the source is in question.
Background: Consumer hand cleaners have surfactants in there that are moderate foamers. In some formulas, a secondary surfactant is added. These aid a little in capturing human sebum, but their biggest quality is making larger, weaker charged micellar structures. These are really good at bubbles. Consumers like bubbles, because of the perception of cleaning efficacy.
Also, the concentration of active ingredients provides a thin film at 6 to 10x the critical Michelle concentration. So, one squirt from the bottle provides more than is absolutely needed, by quite a lot.
Last piece of background, micellar efficiency is only slightly affected by temperature. The difference in cleaning efficacy between 30 & 40C is nearly negligible.
So here's the tip.
Use water at around 85 or 90 degrees F. Warmer than skin temperature, but doesn't have to be hot.
Use a half squirt & wash for 3 to 5 seconds. Rub hard enoght to see a thin film of white lather.
Rinse & repeat.
You'll still use the same amount of product, so you're not overusing and doing it twice is more effective that once for a "Happy Birthday" period once.
In addition, keeping the concentration down lowers the potential for an n drying, so folks that are going farther than needed with # of times washing won't experience the chapping and rawness people are writing about.
To sum up, half the amount, twice with slightly warm water will do the job very well and protect your skin.

[Throck]

1. Intensive Care Scrub

Many years ago when my son was born he was in intensive care. Before we could visit, hold, feed him we had to do an intensive care scrub down on our hands.

Basically a small hand "brush" gets into the crevices of the fingerprints, concave surfaces of the nail and under the nail tips.

After 29 years we still have that scrub brush, we've added a few more. Basically the brush is a 1"x2.5" vegetable brush if you need to improvise.

I still use it after gardening and doing engine work. It cleans out the worst dirt and carbon you could possibly get into.

[ProfessorGAC]

2. Sure

Just do it twice with half the soap.
Also, I should have added that synthetic cleaners (what we call detergents) are better at ruining a virus' day better than traditional soap. Almost all liquid soap formulas are not actually soap, but a detergent blend.
And don't worry about a thick rich lather. The surface chemistry has nothing to do with the foam a quarter inch from the surface.

[Throck]

12. Back in the day; Phisoderm.

It never foamed.

Although today for garden and engines I use Dawn dishwashing detergent.

[DesertRat]

9. That's a good tip. Thanks

[frazzled]

3. Yeah, I'm turning down the hot

Our condo building had to get a new hot water heater a month or so ago, and the new one is providing scalding water (someone needs to dial it back). I knew that hot water was not necessary for washing hands even before this, but somehow it gave me some (erroneous) mental assurance to think that the heat would also help to scare away the virus.

But now that my hands are falling victim to the heat, I've toned it down to warm. However, that often involves several hands-on adjustments to the kitchen faucet, and our bathroom faucets are dual knobs, so I have to touch both. That's not so great either. Oh well. I just keep washing and moisturizing.

[cayugafalls]

7. Micelle Concentration

https://en.wikipedia.org/wiki/Critical_micelle_concentration

[DesertRat]

8. thanks!

[cayugafalls]

10. Your welcome.

There was a spelling error in the op...no biggie.

Stay well

[ProfessorGAC]

15. Sorry About The Typo

I'm not supposed to get micelle wrong!

[cayugafalls]

17. Typos happen, no worries. We are all here to help!

Getting a conversation started is a good thing!

Thank you for the OP.

I personally think a concentration of Michelle's would be a good thing...

Stay well.

[cayugafalls]

5. I was taught how to wash my hands 45 years ago when I worked at a hospital.

Never thought much about it, until people started wondering how to wash hands and it became a popular video on YouTube.

20 seconds is standard in the hospital setting (2 happy birthdays) for non-surgical prep (for surgical prep - 5 minutes is standard for the first wash of the day). I have it so ingrained in my mind that 20 seconds and lather up is the proper way that it would be hard for me to change that now. There is also a certain method for insuring all surfaces are covered with soap.

Hot or cold water does not matter as far as I know, it is the soap that does the work in breaking down the structure of the virus.

This is from Mayo Clinic.

https://www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/hand-washing/art-20046253

I thought I would throw this out there.

Stay well and wash your hands!

[ProfessorGAC]

13. Longer Is Probably Better

But not likely measurable.
My point really was half the soap, twice is way better.
And dont worry about the thick rich lather.

[ThoughtCriminal]

6. Don't be Evil

[ProfessorGAC]

14. Perhaps

But, twice for 5 seconds isn't complicated.
And I'm saving excess soap.
I know it's not that costly, but it costs something.

[Ilsa]

16. And hot water is harder on the skin.

Everyone needs to be mindful of their skin integrity, meaning cracks, raw-ness, sensitivity. The extra washing and chemical can really dry out skin. Don't overdo the heat.

[Lars39]

18. Slightly Off Topic, but What about diluting hand soaps?

Is that totally screwing up the efficacy of the soap? They seem too thick to begin with.
Also, I've been adding bar soap slivers to an empty hand soap bottle and adding about 1/2 cup or so of boiled water. Do you think that's still effective?

[ProfessorGAC]

19. You Could Some

Couple points you've raised.
As I said, the CMC is reached with far less than a squirt, so diluting by half and using a full squirt would be the same as half a squirt.
However,....
The active ingredient (primary) is either a 70% flowing gel, or a 30% liquid. The lower of these is a fairly thin liquid.
When they're diluted to 6% they get really thin. So, the formulators perform a physical chemistry magic trick.
When you add sodium chloride (yep, just salt) the phase structures rearrange due to the change in overall ionic strength & competing solubilities.
So adding salt thickens the mixture to what you buy.
Interestingly, the viscosity increase follows a curve, but when you get to a certain salt level, it crashes on the other side.
I admit I'm not sure where the salt is at on the curve, but if you dilute, you might run backward on the curve and get a viscosity close to water.
Now, you've got something that could pour through your fingers, thus wasting product.
And the surfactant to salt ratio is not linear to concentration. So, it's possible (slightly) that you flip the other way & make it thicker. You already think it's too thick!
I suppose you could experiment with an ounce of it and try adding some salt until you like the consistency.
Seems like a lot of work, though.
Just use half a pump and you'll still effectively clean your hands.

[Lars39]

21. Good to know there might be a fix!

I'll try to remember to do half a pump. Thanks for taking the time to explain all of that.

[Brother Buzz]

20. Old school nurses emphasize the importance of suds, the lather, or simply the bubbles

The evil coronavirus is protected by a fatty layer, and the suds simply make better contact to break down the protective fatty layer, and warm water absolutely helps. The eggheads could explain the physics better, but it has something to do with surface tension (Bill Nye, please pick up the nearest White Courtesy Telephone).

Half the amount, twice with slightly warm water will do the job is sound advice, and She Who Must be Obeyed, one of those old school nurses, totally agrees.

[ProfessorGAC]

22. Hey, Buzz

I am the science guy!!! (And, I've eaten dinner with Bill. Go figure)
Surfactants do not, in fact, need water above room temperature to micellize fat molecules.
The break down of the fatty layer also doesn't require it.
The fat is literally dissolved into the suspension of surfactant & water at the surface. A little lipid removal is a lot on a virus!
You're right about surface tension. That's what surface active agents do! They alter the surface tension of both the water (which has high surface tension) and the soils, which have lower tension.
Lather, however, is not scientifically valid. The soils are trapped at the microscopic (macromolecular) level.
Suds that are 3/16" from your skin are irrelevant when the encapsulation is happening in the 500 microns from the surface.
Suds are a visual appealing result and people believe that it's working because of them.
In fact a few laundry detergents add betaines or amine oxides to the formula. They are gentle, secondary surfactants that are nearly useless in a heavy application like laundry.
Why is it in there? Makes nice bubbles in case the consumer checks for foam. In fact, in laundry, the best surfactants (anionic & nonionic) are low foamers! But, they're great at cleaning!
Surface chemistry & physical organic chemistry have tons of applications in every day stuff!
When I was working, I went so far as go to stores, pull products off the shelf, and list what consumer products had which of our active ingredients in them.
Then everybody who worked there (450 at just one site) could relate what they do to every day products. Folks seemed to like it.