xvi. Measure the solution concentration by weighing out a small weigh boat and then adding 0.1 ml of concentrated silk solution to the boat. Due to the high viscosity of concentrated silk we suggest to use either large orifice pipette tips or cut the tip of the pipette off. Dry the solution at 60 °C and then weigh the dried film. The weight of the silk divided by the volume used (0.1 ml) will yield the weight per volume percent.