Blowing bell

The cavities of the blowing bells should be maintained as small as possible to decrease the time of reaching the maximum forming pressure and to reduce compressed air costs. 

Transfer from the preparation bell jar to the sample chamber was accomplished by first backfilling the system with dry nitrogen or argon for several minutes. When the bell jar was removed, the sample was quickly moved to the chamber while continually blowing the inert gas across it. While this process does involve brief exposure to air, our results show that the effect of exposure to oxygen in the dark was largely reversible. Thus, we believe that any effects due to this transfer are small. 

The dust-laden test surface was placed under a vacuum bell-jar and the required vapor concentration was created by evaporating the liquid released by a dropping funnel in the jar. The space under the jar could be filled with any gas. Detachment of the particles was effected by means of a blow from an arm 2 on the dustladen surface 1. The elasticity of the substrate and the force of the blow from the impinging arm were the same in all the experiments this ensured a constant value of the detaching force and made it possible to compare experimental results. 

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