Hello! Happy to see another person who pushes the boundaries on sugary additives
I don't have experience with evaporated goat's milk, but I have used up to 4x the goat's milk powder needed for the water used in my batch - so instead of 100g GM I soaped with 100g 4x GM concentrate. I would think that it's similar enough to undiluted evaporated milk.
As Zany_in_CO mentioned, if you want to do that you will need to be careful of your soap overheating. My 2x GM batch was made in individual cavity moulds, which I put in the fridge. You may not need to refrigerate if you're not an obsessive gel-suppresser like me
You'll also need to be mindful of the extra superfat the milk concentrate will bring to your soap, leading to soft soap - mine only hardened fully after 3 weeks.
In terms of the overall qualities of the soap...using a 2x GM concentration in place of full water came out just fine for me. I found my 2x GM soap kind of gross until it had cured for about 8 weeks. The sickly-sweet goat milk smell was strong, and once it had reacted with the lye it smelled kind of...pukey? It might be less of an issue if you fragrance it though. After 8 weeks it smelled fine. Seemed very "creamy" when used, but I'm not sure I'd do 2x GM very often.
NOTE: Rather than canned evaporated GM, I prefer using Meyenburg powdered goat milk -- add to the oils before adding the lye solution. I don't have to fiddle with freezing the milk ahead of time. It's just easier.
:bunny:
I do this as well and am a huge fan of it
It also really helps me with cramming a large amount of "goat's milk essence" into my soap if I water discount.
Let me know if you want to know something about working with GM concentrates and water discounts. I mentioned "up to 4x concentrate" in the beginning, but have only used a 4x concentration in the context of a steep water discount. In the context of replacing full water, I've gone up to 2x concentrate.