wick composition and design is specific to the wax type (veg or crude derived). Veg waxes are generally lower melting point, higher viscosity and larger large molecules. Wick symptoms are caused by poor combustion and ventilation. Wick material and make up, influences how much liquid wax is delivered to the flame. Generally if too much fuel is delivered to flame, you end up with incomplete combustion, and the result is soot/carbon build-up. Hence mushrooming. Wick composition and material types, that make up various wicks and sizes have the effect of either retarding or enhancing fuel flow to keep the flame burning. Certain wicks also burn hotter than others, the function of this is aimed at the various base wax melting temperature, wax molecular structure and container sizes. So generally the wax viscosity at a specific melting point will have major influence on flame size and tendency to mushroom.