... This recipe calls for isopropyl alcohol which is usually 70 percent, but be sure to check the label. I have 190 proof grain alcohol (95 percent pure) in my shop for mixing shellac. I'll use that but will dilute it down to 75 percent first.
The recipe doesn't 'call
' for any particular strength of alcohol but it doesn't work with 70% alcohol. Lets do some math:
The recipe calls for two parts alcohol per one part aloe gel. If we use 70% (ordinary rubbing) alcohol then 2 parts of 70% rubbing alcohol gives us 2 x .7 = 1.4 parts isopropyl alcohol. When you dilute that to 3 parts with aloe gel you have 1.4 parts alcohol per 3 parts hand sanitizer mix. That's 46.7 percent. aka not enough.
Doing the same math with 90% isopropanol we get 2 x .9 = 1.8 parts alcohol and 1.8 parts alcohol in 3 parts hand sanitizer is 60 percent.
You can make do with 70 percent but you need to use a 6:1 ratio of alcohol to aloe and your sanitizer will be slightly less effective because it will be runny and will dry faster. Best to use 90% isopropyl alcohol if you can find it.