No, do not lick the soap! And do not waste your time with pH strips; they are notoriously inaccurate, plus the pH number absolutely does not tell you if the soap is lye-heavy.@AliOop , really, no one licks the soap? When I looked up "zap test" I saw 3 ways to do it. One, touch the soap to your tongue , two, moisten a little corner of the soap, swirl your finger tip around on the moist soap, then touch your soapy finger to your tongue again! Three, buy a Ph soap test kit. So, did you mean you don't "lick the soap" like it's a lollipop -- you only "lightly touch the soap to your tongue." Or did you actually buy a Ph soap test kit? As disgusting as soap tastes, don't most people do the tongue test anyway? I'm just wondering. Show of hands?
This article explains all that, and also gives the correct procedure for a zap test, which is touching your soapy finger to your tongue, as you noted.