has been produced for many centuries and over that long period of
time the method of production changed very little. Neutral oils
or fats, including beef and mutton fat and whale oil, were boiled
with alkalis, particularly potassium and sodium hydroxide, to form
metallic salts of fatty acids, or soaps. Glycerol was liberated
as a valuable by-product.
The quality of soap produced depends very much on the quality of
the materials used. Early soap production used ash, produced by
burning various vegetable materials, including kelp, as a makeshift
source of alkali.
production of ash from kelp was a major industry in Scotland in
the western and northern isles during the 18th and 19th centuries.
Kelp industry was introduced to Orkney as early as 1722 by a progressive
landowner, James Fea of Whitehall, Stronsay. There was some suspicion
of the industry to begin with as the kelp was a useful fertiliser.
The seaweed was burnt to produce alkali which had uses not only
for making soap but also glass.
seaweed washed ashore, known locally as' tangles' was collected
and usually burned in shallow stone-lined pits, which can be seen
in many places around the Orkney shores, and became a valuable industry,
bringing in during the French wars, some £20,000 per annum,
and employing up to 3000 people.
success of the industry produced large profits and led to attempted
innovations. On Papa Stronsay large kilns were built to replace
the simple stone-lined pits. It is not known if these kilns were
a great improvement on the more traditional method.
short history of soap.
Kelp on Loch Scavaig, Isle of Skye
Loch Duich, Ross-shire 1814. William Daniell
Kelp burning can be seen on the shoreline
Kelp burning on Papa Westray, Orkney
Kelp kilns on Papa Stronsay, Orkney