All oils/butters contain wonderful properties, however, not all are suitable to use when making coldpressed soap. Each oil/butter has something called an INS value - Iodine Number Saponification - and it is this number you need to work out if your chosen oils/butters will make a great beauty bar of soap. You need a soap that will stand up to being used in the shower, bathroom and kitchen. To soft and it will bcome soft and slimy on the bottom and leave a mess in your soapdish, too hard and you will not achieve a lather. A hard soap is usually used for clothes washing.
The mystery of INS – Iodine Number
Saponification Value :
In the early 1900’s scientist
developed a rough way to predict the ‘hardness’ of soap when made with certain
oils and butters and they came up with the INS value.
The Iodine number is how much
unsaturated an oil is.
The Saponification Value is used to
work out how much lye is needed to convert the oil to soap.
The INS value is :
Saponification value minus the Iodine
The higher the number the harder the
soap is supposed to be.
Values range from minimum zero to over
250. A value to stay around for a good soap is 145- 160
A good soap doesn’t just need the
correct INS value it needs good oils and butters with great properties for
looking after skin!
Thank goodness for the internet as
these days we do not have to calculate the INS value using pen and paper we can
download a table for ourselves to use. I have given you some good websites that
might be able to help you.
If you see a recipe on the internet
that you think would be a great soap to make I would advice that you take a few
minutes to work out on a calculator if it really would make a soap suitable for
use – sadly, not all recipe on the web actually work well as a soap.
On the next page you will see a list
of oils/butters that you have probably heard of – some we even cook with – and
beside each one is a number, ranging from a minus number right up to over 300.
These are the INS numbers that you need to calculate whether or not you get a
good bar of soap.