Mixing alcohol with aluminum sulphate
It looks like you added the alcohol before the glycerin.  Possibly the aluminum sulfate would be more soluble with the glycerin in there, so try adding that before the alcohol.

Wikipedia calls aluminum sulfate only "slightly soluble" in alcohol, so the alcohol addition would be expected to lower the solubility of the salt.  Nothing is reported there about the impact of glycerin.

Upon further review

Nope, we now find this did not work.  Hence as other answers indicate, we need a more careful approach.