Not sure if this helps - From Encarta

Soft soaps are semi-fluid soaps made from linseed oil, cotton-seed oil, and
fish oils, which are saponified with potassium hydroxide. Tallow used in
soapmaking ranges from the cheapest grades, recovered from waste and used
for cheaper soaps, to the best edible grades, used for fine toilet soaps.
Tallow alone yields a soap that is too hard and too insoluble to provide
satisfactory lathering, and therefore it is usually mixed with coconut oil.
Coconut oil alone yields a hard soap that is too insoluble for use in fresh
water; it lathers in salt water, however, and is used as marine soap.
Transparent soaps usually contain castor oil, high-grade coconut oil, and
tallow. A fine toilet soap made of high-grade olive oil is known as castile
soap. Shaving soap is a potassium-sodium soft soap, containing stearic acid,
which gives a lasting lather. Shaving cream is a paste that is a combination
of shaving soap and coconut oil.
Microsoft® Encarta® Encyclopedia 2003. © 1993-2002 Microsoft Corporation.
All rights reserved.



"Chris Hogg" wrote in message
...
Would some kind person admit me to the mysteries of using soft soap as
a mild insecticide?

What constitutes soft soap in this context? I presume washing-up
liquid isn't appropriate. Do I have to cut a chunk of a piece of
'Knight's Castile' or 'Imperial Leather'? Is soap for washing clothes
the right stuff such as Persil or Lux?

How much soap should I add to how much water (grams/litre,
ounces/gallon or whatever)?

How does it work? I've seen one suggestion that it clogs the breathing
tubes of the insects as it dries. Another explanation is that it
simply lowers the surface tension of the water and this then fills the
breathing tubes, so they effectively drown.

All advice gratefully received.


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net