Getting by during COVID-19: Hand sanitizer

Hand sanitizer, and the ingredients to make it, were some of the first things to fly off store shelves once people realized that we’ll be dealing with COVID-19 for awhile.  Hand washing is more effective than using hand sanitizer, but hand washing isn’t always practical in every situation.  I fully acknowledge that you might not have what you need to make your hand sanitizer, but you might have what you need to make a WHO-approved version and not know it.

The problem with the WHO recipe (https://www.who.int/gpsc/5may/Guide_to_Local_Production.pdf) is that it assumes you are making huge batches of hand sanitizer for a community, but I did the math to divide the recipe into smaller amounts.  Feel free to divide all of the ingredients for your chosen formulation by 2 or 4 to make a smaller amount.  I went with a 1 L final volume because it made that part of the math easy.

There are two formulations that use different disinfectants (one uses ethanol and one uses isopropyl alcohol).  Ethanol is the type of alcohol that people drink, which is how distilleries are easily making ethanol for hand sanitizer production.  If you have a bottle of grain alcohol lying around, you might have what you need for this formulation depending on proof (what percentage of alcohol it contains).  Pure ethanol would be 200 proof.  Don’t use vodka for this, like some people have suggested.  It is only 40% ethanol (or 80 proof), so it isn’t strong enough to clean your hands.  You also shouldn’t use fuel-grade ethanol.  It can be used to disinfect things, but it has trace amounts of other things you don’t want to be slathering on your hands.

Caution: for all formulations it is extremely important that you use the right percentages for your ingredients.  If you use the wrong one you can accidentally make something that won’t work.  If you are savvy with dilutions, it is possible to use a lower percentage for your disinfectant and add less water at the end, but if you aren’t comfortable with chemistry I don’t recommend it.  For each formulation, use the instructions in this WHO document for how to put the ingredients together.

Ethanol formulations

1 L Ethanol formulation using mL measurements and 96% ethanol (192 proof):

833.3 mL 96% ethanol

41.7 mL 3% hydrogen peroxide

14.5 mL 98% glycerol

Fill up the rest of the volume with distilled water so the total volume is 1L (should be close to 110.5 mL).

Not everyone has precise graduated cylinders lying around at home, but a lot of people have kitchen scales that can measure in grams.  At 20-25 degrees C (room temperature), you can use the density of your ingredients to convert the measurements into grams.

1 L Ethanol formulation using gram measurements and 96% ethanol (192 proof):

670.8g 96% ethanol

41.7 g 3% hydrogen peroxide

18.125g 98% glycerol

Assuming that you would have needed to add 110.5 mL of water to get the total volume to 1L, you would add 110.5 grams of water (the density is about 1g/mL).

 

Let’s say you have alcohol of a different proof at home.  You might still be able to substitute it in and use less water.  If your proof is 169.5 or greater (84.76% ethanol) you are still in business.  If you don’t know the proof of the alcohol, and can’t measure it precisely, then don’t use it.  Sadly, this means that 151 proof alcohol won’t work (this is the highest proof you can buy in some states).  However, if you have 190 proof alcohol you are good to go.

1 L Ethanol formulation using mL measurments and 84.76% ethanol (169.5 proof):

943.8 mL 84.76% ethanol

41.7 mL 3% hydrogen peroxide

14.5 mL 98% glycerol

No added water

1 L Ethanol formulation using mL measurments and 95% ethanol (190 proof):

842 mL 95% ethanol

41.7 mL 3% hydrogen peroxide

14.5 mL 98% glycerol

Fill up the rest of the volume with distilled water so the total volume is 1L (should be close to 102 mL).

1 L Ethanol formulation using gram measurments and 95% ethanol (190 proof):

677g 95% ethanol

41.7g 3% hydrogen peroxide

18.125g 98% glycerol

Assuming that you would have needed to add 102 mL of water to get the total volume to 1L, you would add 102 grams of water (the density is about 1g/mL).

 

Isopropyl alcohol (aka rubbing alcohol) formulations

The WHO formulation calls for 99.8% isopropyl alcohol, which most people won’t have at home.  The most common percentage is 70% isopropyl alcohol, but other common percentages are 50%, 91%, and 99%.  In order to be effective, you need to use an isopropyl alcohol solution of at least 79.46%, so unfortunately the bottle you have in your medicine cabinent might not be strong enough.

I have been told by my spouse that you can purchase high percentage isopropyl alcohol solutions (~100% isopropyl alcohol) under the name “5100 screen frame prep cleaner” from print shops (for example https://nwgraphic.com/sads/screensystems/5100.pdf) or 824 isopropyl alcohol, 2-propanol, or IPA 99 from electronics chemical suppliers.  Read the safety data sheet of any product you are considering to make sure you know exactly what is in it.

1 L Isopropyl alcohol formulation using mL measurements and 99.8% isopropyl alcohol:

751.5 mL 99.8% isopropyl alcohol

41.7 mL 3% hydrogen peroxide

14.5 mL 98% glycerol

Enough distilled water to make the total volume 1L (should be about 192.3 mL)

1 L Isopropyl alcohol formulation using gram measurements and 99.8% isopropyl alcohol:

589.9g 99.8% isopropyl alcohol

41.7g 3% hydrogen peroxide

18.125g 98% glycerol

Assuming that you would have needed to add 192.3 mL of water to get the total volume to 1L, you would add 192.3 grams of water (the density is about 1g/mL).

 

1 L Isopropyl alcohol formulation using mL measurements and 91% isopropyl alcohol:

824.17 mL 91% isopropyl alcohol

41.7 mL 3% hydrogen peroxide

14.5 mL 98% glycerol

Enough distilled water to make the total volume 1L (should be about 120 mL)

1 L Isopropyl alcohol formulation using gram measurements and 91% isopropyl alcohol:

647.8 g 91% isopropyl alcohol

41.7g 3% hydrogen peroxide

18.125g 98% glycerol

Assuming that you would have needed to add 120 mL of water to get the total volume to 1L, you would add 120 grams of water (the density is about 1g/mL).

 

A note about glycerol

Glycerol is getting harder and harder to find (probably because people are making hand sanitizer with it).  This is what the WHO says in its instructions:

  • Glycerol is added as a humectant to increase the acceptability of the product.
  • Other humectants or emollients may be used for skin care, provided that they are affordable, available locally, miscible (mixable) in water and alcohol, non-toxic, and hypoallergenic.
  • Glycerol has been chosen because it is safe and relatively inexpensive. Lowering the percentage of glycerol may be considered to further reduce stickiness of the handrub.

I’ve seen various substitution recommendations online, but I’m not sure how much to trust any particular one.  Here are some ideas of unknown quality from the internet:

Disclaimer:

I have done my best, but there may be one or more typos, copying errors, or math errors in here.  I submit this to you in good faith, but can’t guarantee its correctness.  Also, don’t forget that alcohol is flammable.  Be careful how you store it, and keep it away from open flames.

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