Formalin, by definition, is 37% formaldehyde. 37% formalin would be 0.12% formaldehyde.

If Formalin is indeed 37% Formaldehyde, then 37% Formalin would be 0.37 * 0.37 * 100% = 13.7% Formaldehyde. I have no idea where that 0.12% number could possibly come from.

Trying to be the best of whatever I am, even if what I am is no good.