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The raw materials of
which soap powder is made are soap and soda, to which ingredients an
addition of talcum or water glass can be made, if desired, these materials
proving very useful as a filling. An excellent soap powder has been made of
20 parts of crystallized soda, 5 parts of dark-yellow soap (rosin curd), and
I part of ordinary soft soap. At first the two last mentioned are placed in
a pan, then half the required quantity of soda is added and the whole is
treated. Here it must be mentioned that the dark-yeltow curd soap, which is
very rosinous, has to be cut in small pieces before placing the quantity
into the pan, the heating process must continue very slowly, and the
material has to be crutched continually until the whole of the substance has
been thoroughly melted. Care must be taken that the heating process does not
reach the boiling point. The fire underneath the pan must now be
extinguished, and then the remaining half of the crystallized soda is added
to be crutched with the molten ingredients, until the whole substance has
become liquid. The liquefaction is assisted by the residual heat of the
first heated material and the slow cooling facilitates the productive
process by thickening the mass, ad when the soda has been absorbed, the
whole has become fairly thick. With occasional stirring of the thick ened
liquid the mass is left for a little while longer, and when the proper
moment has arrived the material contained in the pan is spread on sheets of
thin iron, and these are removed to a cool room, where, after the first
cooling, tfley must be turned over by means of a shovel, and the turning
process has to be repeated at short intervals until the material has quite
cooled down and the mixture is thoroughly broken. The soap is now in a very
friable condition, and the time has now come to make it into powder, for
which purpose it is rubbed through the wire netting or the perforated
sieves. Generally the soap is first rubbed through a coarse sieve, and then
through finer once, until it has reached the required conditions of the
powder. Some of the best powders are coarse, but other manufacturers making
an equally good article prefer the finer powder, which requires & little
more work, since it has to go through three sieves, whereas the coarse
powder can do with one or at most two treatments. But this is after all, a
matter of local requirements or personal taste. |