When a recipe calls for 15 oz of lye is it by weight or in a measuring cup?

Here is the answer to your next soap making question:

It is difficult to know without seeing the complete recipe, but I expect it means 15oz by weight, of lye flakes, or pearls.

As a guide, when I make a 3kg batch of soap (which is about 15 x 4oz bars), I use about 15oz of lye pearls.

Most soap making recipes list ingredients by weight, even for liquid ingredients. This simplifies the recipe and avoids geographical differences in liquid measurement, for example one US liquid ounce is not exactly the same as one UK liquid ounce and a US Pint is 16 ounces, whilst a UK Pint is 20 ounces. The use of dry weight is more universal and thus reduces errors.

More soon.

What's the easiest and neatest way to cut loaves of cold process soap?

Here is the answer to your next soap making question:

I have discovered that knives don't really work, because it is difficult to cut straight and can crumble the lower edges of the bars, by far the best method is a cheese wire. If you want to cut a small loaf you could use a cheese board with a wire attached.

More soon.

How do I add things like milk and honey to a soap recipe?

Here is the answer to your next soap making question:

Milk is generally used instead of (or as well as - depending on the quantity required) water when dissolving the lye. Honey can be dissolved into this mixture just before it is stirred into the oils.

It is important to introduce the milk slowly, or as the lye heats the mixture it can begin to cook the milk giving it a brown color, whilst not actually harmful to the final soap, it may be undesirable if you were aiming for a pale green or blue soap color.

More soon.

Cold process verses melt and pour?

Here is the answer to your next soap making question:

This topic is explained in quite some detail during the first few lessons, both techniques are very useful in the right situation. Look out for Day 3 which explains this in greater detail.

More soon.