HP Soaping - adding milk after cook?

[SkyeSurfer]

I came across this recipe in my newbie research, and I’m curious what the more experienced soapers will make of it:
https://www.modernsoapmaking.com/creamy-hot-process-goats-milk-soap/

The theory is that by adding the milk after the cooking process, you avoid the discoloration that would typically occur. But if you’re adding something like milk after the cooking is completed, and you’re not adding a preservative, wouldn’t there be a risk of mold or other spoilage?

 

[Primrose]

I'm interested in the answer too. I don't do HP but I do CP with goats milk and would have made the same conclusion as you

 

[Complexions]

In that original post, the creator explained in the comments section why you can add the dairy at the end of the cook when someone asked her. I reserve 20% of my fluid for after the cook in the form of heavy cream, coconut milk, etc. warmed up, with a little sodium lactate and honey (don't want to add cold milk/additives to hot soap). Even after a year, no traces of spoilage in my bars of HP soap.

 

[SkyeSurfer]

I did see her comment, but I thought her explanation was odd. She said it doesn’t spoil because of the lack of water and high pH. If you’re adding the milk when the soap is done, the pH wouldn’t be all that high anymore, and there’s plenty of water in the milk itself.

I’m very happy to know that it works, because I’m excited about making some. I’m just not sure what the science is behind the lack of spoilage. Oh well, I’ll just call it magic and make some soap. XD

 

[earlene]

Actually, the pH of soap is still high when it is finished. Lye Soap is generally around pH 9-10, which on a scale of 0-14, is still considered high.

But it's not just the alkalinity of soap that affects the milk. The heat used in Hot Process also cooks the milk. So the combination of heat and the high alkalinity of soap changes the composition of the milk, altering the the molecular composition. I have made many soaps with milk and milk products, including making HP soaps with yogurt added at the end to make it more fluid for easier pouring. So far none have spoiled or grown mold or anything untoward. Some of these soaps are 2 years old and remain fine.

By 'lack of water' I believe what she means is that there is not 'a whole lot of water' in a bar of soap, as opposed to liquid soap, which is predominantly water.

 

[gloopygloop]

I have added milk after cook many times and it works fine has never spoiled or given dos etc. mostly I have used powdered milk mixed with either a littel oil or water from batch but I have added natural milk also and that has worked fine, powdered is just so much more convenient for me as I am a city person without grazing goats sadly! Any how final soap has always been super good, no ammonia smell, no dark caramel colour.

 

[Complexions]

What earlene said!

 

[Primrose]

This is really interesting, thanks to everyone for the input!

So how does this compare to M & P, as I'm pretty sure I've read you cant add milk to M & P because saponification is already complete, so the milk will spoil?

 

[earlene]

The general consensus is that, yes, fresh ingredients, even reconstituted powdered milk, will spoil given enough time in M&P soap. I am pretty sure that's why there are so many MP bases available, including GM M&P base, so you can have the best of both worlds.

I don't know how all the additives that may be in MP soap affect pH (they may, and they may not), but I do know MP bases cool pretty darn fast, sometimes too fast to do intricate designs. So there just wouldn't be enough time for the heat and the pH to work together. At least that's my thinking on the matter. I could be entirely wrong.

 

[Lin19687]

Make sure to WARM up the 'milk product' before adding.
I added yogurt and obviously didn't get it warm enough as I have a couple "clumps" so not sure if it was a curdle or what. I think I got them all mixed in but finally I had to add the salt so I left it.
These were soaps for testing recipes so not selling them.

 

[IrishLass]

So how does this compare to M & P, as I'm pretty sure I've read you cant add milk to M & P because saponification is already complete, so the milk will spoil?

This is just my own experience with goat milk in M&P: My sis once had an inlaw that made M&P to which she would add fresh goatmilk from her goats, and she would often gift such soaps to my sis........and always, this would happen- part way through using a bar- it would start smelling like vomit and she's have to throw it away because the smell was so yucky. My sis had me try an un-used bar once to see if it was just a fluke that only happened to her, and sure enough, it started smelling like vomit for me, too, after I had used it a few times.


IrishLass

 

[Laurabolyard]

So... I've used yogurt in my last few HP batches with great success. I'm wondering if sour cream or heavy cream can be used. Is there a reason for yogurt, specifically? Sorry for the hijack!

 

[earlene]

Yogurt has a high amount of lactic acid, and helps keep the batter more fluid in HP to help with the pour. That is if you use enough of it and keep from allowing too much liquid to evaporate off by not keeping it tightly covered during the cook.

But, yes, of course you can add any milk product you like. However yogurt is a fermented milk product (as is Kefir) so has a higher content of lactic acid.

 

[Complexions]

So... I've used yogurt in my last few HP batches with great success. I'm wondering if sour cream or heavy cream can be used. Is there a reason for yogurt, specifically? Sorry for the hijack!

I have never tried sour cream but heavy cream works well

 

[Lin19687]

I have a 1/2 gallon of milk that I think I should turn into Yogurt today I don't usually have 'leftover' sour cream though

 

[Iluminameluna]

Hi, I'm still fairly new to soaping but I'm reading as much I can.
I'm curious about the yogurt at the end, when I've made HP soap.
My recipe only included lard (5.95 oz) as a solid fat. The rest were: canola (10.2 oz), olive (5.8 oz) and very little castor oil (1.85 oz). I used 1 oz total of eo's (half each of lavender and peppermint). My lye ratio was 2:1 with 1.5 oz of lye and 3 oz of water.
I added 4 oz of room temp (75°F) full fat yogurt, 2 Tbsp of each sugar and salt you to hot oils.
I tried a whisk for stirring and did so for over 2 hrs, but the mixture never traced.
I did add the yogurt at the end, along with the eo's, when the slimy mixture had cooled to 110°.
And it WAS slimy! The "soap" stayed like putty even after 4 days in the mold (a plastic-lined box), and 2 weeks of sitting in cubes out on my porch, curing.
There's NO sudsing whatsoever, and there's an oily feel on my hands after handling it.
Tonight I rebatched it, adding 1/4 c of water, and it ALL melted in less than 45 minutes. I've now formed it into a log and it'll sit on my porch until I can unwrap it tomorrow night. I have to go into the city in the morning and won't be back home until late.
Would the yogurt have affected it, my not having a stick blender (can't be found here), or the eo's?' I have made a similar batch before. Except for the canola oil and the yogurt, that batch was perfect, but not very appetizing. I wanted to be able to really mold this batch, which is why I added the yogurt, and used canola oil because I didn't have enough of the other oils especially the lard.
Anyone have ideas?
P. S.: I'll be using a cordless drill for mixing next time! I just saw that idea!!

 

[earlene]

Well, I just put your formula into soapee's lye calculator and it's no wonder it never came to trace. You should have use 3.05 ounces of NaOh. Also the water should have been 6.11 ounces if you used a 2:1 lye to water ratio.

Hi, I'm still fairly new to soaping but I'm reading as much I can.
I'm curious about the yogurt at the end, when I've made HP soap.
My recipe only included lard (5.95 oz) as a solid fat. The rest were: canola (10.2 oz), olive (5.8 oz) and very little castor oil (1.85 oz). I used 1 oz total of eo's (half each of lavender and peppermint). My lye ratio was 2:1 with 1.5 oz of lye and 3 oz of water.

 

[Iluminameluna]

Wow, +earlene, I used SoapCalc for my numbers and can't imagine how I could've goofed so badly!!
Maybe I'll rebatch it again, and add the missing lye amount.
Grrr!
I thank you for that!!

 

[earlene]

It's not hard to miss-read numbers. I've done it, too.

 

[Lin19687]

Another reason why I have not soaped all week since I am sick. I don't want to miss read anything.

But it does happen to all of us at some time during the soaping bug