Advantages of Hand Milling
One of the advantages of this method is that you don't subject your additives to the rigors of active lye. You can achieve more predictable color results. Botanicals will hold color longer, and you can use less fragrance material. And, of course, you don't have to handle the lye.
You can get beautifully textured soaps by incorporating dried herbs right in with the soap as you heat it. If you make soap balls by moistening the shreds and packing them by hand rather then melting the soap, you will retain more color in herbs. Remember that the herbs will still turn brown before too long, but the change will not be as fast this way.
Since subjecting essential oils to the lye process can diminish their impact per ounce, combining them with the soap shreds can make them go farther. The rate of use in lye soapmaking is approximately one tablespoon per pound of fats. However, in hand milling, you can use only one teaspoon per pound of soap and get a great effect.
Use high-quality soap for hand milling to get high-quality hand-milled soap. It's much the same principle as cooking only with water you'd actually drink. You can add anything you want to an inexpensive detergent of deodorant bar, but it will never be any better than what it is.