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Mixing
Soap noodles are mixed with ingredients such as perfume, preservatives,
colours, and sometimes miscellaneous ingredients to increase mildness,
improve lather and skin feel. This is where consumer preferences are
taken into account
Extrusion
(plodding)
After mixing, the soap mixture is extruded, under high pressure, through
a steel plate from which it emerges as a continuous bar. The extrusion
process is similar, but on a much larger scale and higher pressures, to
that used by a butcher to make sausages. Extrusion achieves a number of
things, helping to remove air and completing the mixing process, thus
ensuring the bar is homogeneous. Soap homogeneity is particularly important.
The term plodding is used in the industry as an alternative term to extrusion.
Cutting
Immediately after extrusion the soap is cut into equal lengths (billets)
and continuously fed to a stamping machine.
Stamping
The billets at this stage are still quite soft yet firm (like firm plasticine).
Each billet is then pressed (stamped) between two shaped metal plates.
The shape of the plates determine the shape of the soap bar and also can
include indentations reflecting the brand name of the bar itself.
Packaging
The bars are then put into cartons or wrapped ready for sale. Sometimes
the packaging is omitted and the bars sold naked. Packaging does, however
help the soap retain its perfume and prevent it from drying out. For more
information on soap and cleaning products go to www.ukcpi.org
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