A Rotaflo-type stopcock was employed to
ensure that a desirable degassing rate was achieved.
The two components were added together and
mixed vigorously in a 5:1 weight ratio either with a
palette knife or in a heavy-duty mixer, depending on
the quantity that was to be mixed. To make the
composite the barytes (Commercial Mineral Ltd,
standard grade), which had an average particle size
of 63/xm, was added up to the required weight
fraction in 5 g steps while mixing continued.