Your Evaporation Guide – Thickness of evaporating flask

The evaporation rate is noticeably greater if the evaporating flask’s glass walls are thinner. The simple reason is that thinner glass allows better heat transmission from the heating bath through the glass of the evaporating flask to the solvent. Generally speaking, the glass wall thickness should be selected to be as thin as possible, while still being robust enough to prevent breakages of the evaporating flask even at very low pressures. Concerning both these issues, the optimum thickness for a 1 L evaporating flask is between 1.5 and 2.0 mm.