O yes, Covid-19...
The World Health Organization recommends soap, but nevertheless, hydroalcoholic gel
is in huge demand as if it were magic. Unobtainable in France for instance. Making some at home is hence a big temptation.
The scarcity results from regulations essentially. Producing at home looks an interesting initiative. Distribution may be hampered by law. Not my problem here.
For a gel, most patents cite polyacrylate.
Though, the WHO
recommends, as a substitute for soap if no drinking water is available, a home-made liquid
rather than a gel. I've found it in French, not in English:https://www.who.int/gpsc/5may/tools/system_change/guide_production_locale_produit_hydro_alcoolique.pdf?ua=1
For 10L according to that source:
- 8.3L of 95% ethanol or 7.5L 99.8% isopropanol
- 0.42L of 3% peroxide
- 0.15L 98% glycerine
- Rest distilled or boiled cooled water
Mix, wait 3 days before use.
The ethanol must be pure, free of methanol and other poisons added to rubbing alcohol. The peroxide is the usual pharmacy concentration - more concentrated could become very dangerous. Glycerine is often 85% concentrated.
Glycerine serves to protect the skin. This proportion won't make a gel. That's better, because I dislike the feeling of a gel after washing my hands. Thickening by glycerine would need >90%, and then <60% alcohol loses the antiseptic effect.
I would not use ethanol and peroxide regularly on my hands. Soap is better.