Dear Rabbi Simon
I happened to be made aware of a company that is starting to manufacture hand sanitizer that is Hallal, and is not manufactured with any animal products (possibly referring to glycerine). I was thinking about it from a kashrut perspective. My initial thought is that it’s not relevant as hand gel is not food that we eat, and the quantity of animal residue is probably not relevant once processed into hand gel.
But then I started wondering about this. I kind of understand how the likes of glycerine its not relevant to soap, as we wash soap off our hands. but with hand gel, you don’t wash it off. So is it a problem is you use hand gel and then lick your fingers.
I then also remembered that with glycerine, while it doesn’t appear to cause a kashrut problem when used in soaps (including dishwashing liquid), it is a problem when used in processes like colouring white sugar into brown (not talking natural brown sugar of course).
Where does hand gel sit from a kashrut perspective?
Since hand gel is not intended for eating, the tasteless glycerine content need not concern us (even if it is incidentally ingested in tiny quantity on occasion). The fact that it is absorbed into the skin and may be beneficial (even beyond its germicidal properties) is no problem as the Torah forbids consumption but not other types of benefit. However, you are definitely correct that glycerine used in the production of brown sugar should be avoided.
Rabbi Rashi Simon