Electrodeposition research progress report, July 1--31, 1948

The cell used in production plating has a platinum anode and a platinum cathode. The potential at which the platinum cathode rests is not independent of the current, bat varies with it. In order to separate postum from other cations by electroplating out of solution, it is necessary to establish the plating potential at a value which will allow complete plating of postum, but will preclude the deposition of as many other cations as possible. This potential has been found to be about 0.00 v. to the normal calomel electrode. The procedure for determining the amount of loss postum as related to the time between the removal from the plating bath and the immersion into the water rinse has been worked out. Two runs have been made, neither of which were very successful because of mechanical difficulties which occurred during the runs. The second run showed, however, that as the time increased the amount remaining in the water rinse also increased very rapidly. It has been found that a very excellent method of removing suspended material from a solution of aqueous hydrogen fluoride is to filter it through a funnel machined out of teflon with a disc of a porous teflon sheet. It was found that the spongy teflon used in this experiment had a porosity of about 16.5 microns. It was possible to reduce the size by compression to about 2.0 microns. In this way any porosity of material can be obtained depending on the original size of the pores and on the pressure used to compress it