Mixing Lye with Milk Questions

[KiwiMoose]

I regularly make coconut milk soap ( split method) and oat milk soap (semi split). I find that adding lye to the oat milk tends to make it very thick and clumpy so i started splitting half of it ( half with the water and half with the oils). It still goes thick, but it's more manageable that way.
So - I have had a request from a woman to make breast milk soap ( apparently she has a freezer full of the stuff!) I would prefer to use my full amount of water as milk in this case because if i split it I will only 150g which is less than half a baby bottle full ( and won't make a dent in her freezer-full).
So for those of you who regularly make animal milk soaps ( it will be a first for me) how should I do this? Won't the lye make the milk start saponifying? I know that I will need to freeze the milk to avoid scorching - and I assume I should use cavity molds so it doesn't gel? And when I mix the lye will the milk go gluggy? Please tell me everything so i can be prepared. I think it might stink to high heaven as well?

 

[MullersLaneFarm]

This is the way I've made milk soaps the past 2 decades:

Have your oils weighed & melted, ready to go.

Use large chunks of frozen milk for your lye solution. Add about 1/3 of the lye to the frozen milk & stir to start melting the milk. Add half the remaining lye and stir a little more. Add remaining lye and use your stick blender (keeping it fully immersed) to break up the remaining frozen milk and incorporating your lye. This process should only take a few minutes.

Pour immediately into the waiting oils.

I use slab molds that hold 6 & 12 lb of soap. I stack and wrap the molds in wool blankets to ensure a thorough gel to the edges. The resulting soap is off white in color.

 

[Primrose]

All my soaps are made with full goat milk, frozen. Yes some of the fat will saponify, I use a spoon to squish it through a strainer into the oils and then stick blend as normal

 

[KiwiMoose]

All my soaps are made with full goat milk, frozen. Yes some of the fat will saponify, I use a spoon to squish it through a strainer into the oils and then stick blend as normal

thank you Primrose - do you stick blend the lye mixture too? Or just use the strainer ( that's similar how I do my oat milk)

 

[KiwiMoose]

I had a dream last night that I mixed my lye into the milk and it turned into custard.

 

[MellonFriend]

I do gel my goat milk soap and if you are using a colorant, it doesn't really do anything all that noticeable in medium or dark tones. I have gelled uncolored milk soaps too and they turn a pleasant light peach color. You could probably combat this with some TD, but I've never tried it.

I do what Primrose does with my milk lye solution and I do not stick blend it before adding it to my oils.

 

[Primrose]

thank you Primrose - do you stick blend the lye mixture too? Or just use the strainer ( that's similar how I do my oat milk)

Just the strainer

 

[TheGecko]

I make GMS.

I do a full water replacement. Since milk doesn’t freeze the same way that water does, it’s a simple matter to break up a cube or you can just add a little chilled distilled water.

I start with an ice bath. I use a plastic dish tub I got from the local $$$ store and I fill it halfway with ice, a couple of cups of water and a few tablespoons of salt. The salt helps to keep the ice bath colder. After weighing out my milk cubes, I place the container in the ice bath and let it sit for about five or ten minutes so the container gets cold too. And you want the level of your ice bath to be at least equal to your lye solution. I then add my lye a bit at a time…the ‘bit’ is dependent on the size of batch, but about a fourth or fifth for larger batches. Key is not letting you milk get above 70F. It obviously takes longer to make a milk lye solution, but I think the time is worth it as it results in creamy bars (I don’t color my GMS).

Your milk lye solution is going to be about the consistency of pancake batter and that is because it’s love at first sight between the Sodium Hydroxide and fat in the milk. I’ve even had to a thick consistency with no problem (mother nature’s calls can’t always be ignored). Now some folks will put the milk lye solution through a strainer to break things up or crush/remove any undisclosed bits of lye…I never have. I just give it a quick whiz and dump it in my oils along with my scent. And since I don’t do anything fancy with my GMS, I blend to about a light-medium to medium trace and pour into the mold.

Now comes the big decision…where to put the soap. I don’t gel any of my soaps and I love the creamy matte appearance of my GMS. But there is sugar in milk and it’s going to cause my batter to heat up more than normal during the saponification process. If the outside temp is more than 75F (daytime temp), I put my GMS in the frig with a light cover. 24 hours, then I take it out and let it come to room temp before unmolding. I then wait until the next day to cut. During the winter, the garage is close to frig, but it’s also a damp time of year (we get a lot of rain). I leave the soap in the mold for a couple of day, bring it up to room temp, unmold, then cover with a tea towel for a couple of days before cutting.

 

[Arimara]

I have not made a full milk soap in a long while but I did as others did: freeze the milk though I tried to get it to a slushy consistency. I wouldn't worry about the smell unless it was a sweetish smell but that only pertained to Goat's milk. I have no idea what human milk is like. I never breastfed.

 

[KiwiMoose]

Thanks everyone. I'm going to use cavity molds for this which will help stop the overheating.

 

[KiwiMoose]

So just one last question - I use the milk as the full water amount right?? Won't that make an extra super fatted soap? Should I reduce some of my other fats to compensate or just go with it?

 

[TheGecko]

I thought about doing the math after @DeeAnna mentioned it in post, but I’ve never had any issues and I have a SF of 5% and use Shea Butter at 15%.

 

[KiwiMoose]

I thought about doing the math after @DeeAnna mentioned it in post, but I’ve never had any issues and I have a SF of 5% and use Shea Butter at 15%.

Thanks Gecko - I read that breast milk is about 3-5% fat, so if I use 300g of it, that's only about 15g extra fat ( on top of my recipe's 1000g) , so not really worth worrying about.

 

[TheGecko]

Goat milk has 4% fat and I feel the same way even though I made smaller batches (50oz total). If it was a concern, I'd just lower my SF a percent or two.

 

[DeeAnna]

I agree that compensating for the fat in full fat milk isn't all that critical -- it's reasonable to ignore the butterfat in full-fat milk and simply use it as a replacement for water. That assumption will increase the superfat in the soap by only 1% or so.

The trouble comes when someone uses higher fat milk products such as half-and-half or cream but doesn't take that fat into account.