Support master batch pre-mixes

[nazar]

You pre-mix equal weights of NaOH and water, and use that in your recipe along with additional water (or whatever liquid you're using). So if the recipe calls for 200 g NaOH and 300 g water, you'd use 400 g of the masterbatched lye and add 100 g of additional water. There's a Soaping 101 YouTube video on masterbatching lye that would explain it