The ounces here are weights, right? Except that it asks for 2 ounces of lavender oil, which is a liquid, and is 60ml, which sounds like waaaaay too much. Is there an implied change in the use of the term “ounce” here?
Nope, all liquid measurements. For the thicker ingredients, 1 cup is 8 ounces, the same measurements used for things like butter and shortening.
2 ounces of lavender oil by weight is about 2.13 fluid ounces so it’s not like it makes a lot of difference. Lavender oil density is about 0.939 ounces (weight) per fluid ounce.
I agree that all of those measurements in the recipe are fluid ounces. If they were weights, they would total a little over 4 pounds, but the recipe says it makes 3 lb of soap.
From the context I think the author is referring to ounces by weight.
I’ve been making cold process soap for 14 years and I weigh all of my ingredients with a scale that weighs to one tenth of an ounce. Works fine.