Superfat in Cold Process Soap

Let’s have a closer look on Super Fat in Cold Process Soap. When I started to make soap I didn’t really get the point what super fat exactly is, how to use it or why I should need it. I want to help you a little bit out if you have the same struggle.

If you prefer to watch this article instead of reading it, you can find the video here.

First something about the terminology

Super Fat is a very irritating term. It always suggests that you add something. But you don’t. What it really means is not adding something, it is about using less Sodium Hydroxide. Therefore it is also called lye discount which is a much better term for that.

Lye Discount – What exactly does that mean?

With the saponification value, you can calculate how much Sodium Hydroxide you need for a complete saponification. This means that there is no leftover oil or Sodium Hydroxide at the end.

When you use less Sodium Hydroxide, you will have some leftover oil molecules that weren’t able to saponify completely because they ran out of Sodium Hydroxide to react with.

But here is the point a lot of people think wrong. When you make cold process soap you will not have any oils which are not saponified. You will have a lot of molecules which are completely saponified and some which are partially saponified. You have to remember that the saponification process can take up to 48 hours (or even longer) to complete. In this time all the molecules clash together to form soap. To saponify one oil molecule you need three molecules of Sodium Hydroxide. When you use a lye discount the chance is much higher that every oil molecule has reacted with at least one molecule of Sodium Hydroxide than that there are oil molecules which didn’t react with any Sodium Hydroxide at all.

And there is another important thing to remember. Because the saponification process takes so much time, it doesn’t matter if you add some extra oil after trace. There will be no difference in the cured soap. So, it just doesn’t make sense for cold process soap to add some extra oil or fat when your batter is on trace.

This might look different with hot process soap. By adding heat the saponification speeds up. When you cook the soap for several hours chances are good that it is saponified completely. If you then add an additional oil or fat it will stay mostly unsaponified and you have a real superfatted soap.

But why should you make soap with a lye discount?

There are two main reasons.

The first one is all about safety. A lye discount prevents your soap from being too lye heavy and a lye heavy soap is not good for your skin. You might have some problems with skin irritations when you use a lye heavy soap.

The second reason is the benefit. Soap without a lye discount is mostly a bit drying to your skin. By using a lye discount your soap will be more nourishing and mild.

How much lye discount should you use?

For the most soap recipes 5 to 10% is a good range. When you want to make soap with only Coconut Oil you can go up to 20%.

Are there any disadvantages?

Using a very high lye discount will make your soap very soft and vulnerable to spoilage. Also the more not completely saponified oils you have, the less bubbly your soap will be. So with a too high lye discount you will end up having a very soft soap bar which doesn’t produce much lather.  But within a range of 5 to 10% everything should be fine.

What about Coconut Soap?

Pure Coconut soaps are a little bit different. They are very cleansing and therefore drying to your skin. Also, they will make very hard bars. So using about 20% lye discount in Coconut Soap is a very good option. You could even go up to 25%. Further Coconut Oil is the best oil for a great lather. So a high lye discount will not destroy the bubble fun.