My experience with mixing lye to milk is that you have to take your time or else the milk will curdle or turn interesting shades of orange. The usual amount of time is 10-15 minutes; I just start adding small amounts of lye to the milk and watch the temp — try not to get over 90-100 degrees. If the milk starts to turn orange let it sit a while to cool off.
If you have a problem incorporating milk powder into soap, mix the powder with a bit of very warm water. The milk powder needs the warm temperatures to dissolve completely.
I make pure goat’s milk soap on a regular basis. The way I make my soap is by using only milk and no water. Follow the recipes if using water, just substitute the water with milk. The lye will turn the milk a deep yellow. I set my container of milk in a sink full of ice water to help control the temperature when I add the lye. After I mix the lye/milk with the oils, I like to run the mixture through a blender at least twice. I found that it makes the soap more of a creamy color instead of the dark color that I was getting. I’ve been making soap for 4 years this way. Everyone who uses my soaps enjoy it.
You use a portion of the liquid to mix the lye. Example: 18 oz. liquid, use 6 oz. water to mix the lye and the remaining portion of goat milk. Also you can up the goat milk a bit, say instead of 12 oz. use 14 oz. Always works just fine.
I only make goat’s milk soap. Here’s the way I do it. My recipe calls for 32 oz. of water. I measure my lye, for my basic recipe it is for 12 oz. I then add it to 18 oz. of distilled water. I melt my oils and when the temps are right (100 degrees for both the oils and the lye mixture), I mix them together. Usually within about 10 minutes I’ve reached a light trace. I then add 14 oz. of slushy frozen goat’s milk. This brings me to the required amount of 32 oz. of liquid. Again within another 10 minutes I’ve reached a light trace. I then add my Shea butter, stir, then add my E.O.’s. Within 15 minutes I’m at heavy trace and then pour it into my molds. My soap turns out to a light tan color with no ammonia smell.
Personally I like to add lye to slushy milk. There are several reasons for this. The first is that I get goat and sheep’s milk in gallon jugs from some of my patients, I like to make 3 pound batches and by freezing the milk in smaller containers I can use it as needed and don’t have to waste any. I also don’t like to dilute my milk soaps with any water and actually find it easier to use this method. I don’t have to wait for the lye solution to cool, I can usually add it to the fats as soon as the lye is incorporated. I do make some soaps using powdered milk as well, I keep powdered buttermilk on hand for baking and also have powdered baby formula on hand. These can be added as soon as fats and lye solutions are combined. I guess what ever works best for the individual is what they should go with, but there is no need to be afraid to use milk in soaps, it is a skill that is easily learned.
For nice very light bars I freeze all of my dairy. When I get new milk… I pour into baggies… label and weigh them as I freeze them. When I make a batch of soap… all I have to do is dissolve the lye in 1/4 the liquid content in water… when this is cool to around 95-100°F… I add the frozen almost slushy milk all at once to the lye. I have found that if I added a little milk at a time the milk has a tendency to heat up. If I add it all at once the temp stays low… 85-90°F… I usually get almost white to light cream bars.
A reminder — The usual disclaimers apply. The recipes in this library reflect the individual contributors' own methods of soapmaking and are written in their own words. We cannot personally guarantee the success or results of any of the recipes included in this library.