Issues with buttermilk powder

[rainycityjen]

I've made two batches with buttermilk powder that have turned out really crummy and dry-looking. I'll try to post a picture, but the problem is texture: it pours smooth, but dries very matte with lots of evenly-distributed, very tiny white bumps. I think this may be unmixed powder, but I'm not sure. I want to rule out stearic spots and air bubbles since I heated oils to 170 F before cooling, burped the blender, burped the mold, etc. The bumps didn't appear immediately but are becoming more prominent as it dries. It's also quite ashy though that's probably the FO.

My method of incorporating the powder was to slowly, incrementally whisk it in with a few ounces warm oil, then SB it into the soap at trace. I did the same with some green clay.

Recipe:
5% avocado oil
20% coconut oil
40% olive oil
21% palm oil
15% shea butter
33% lye concentration (384g water/189g lye)
1/4 cup buttermilk powder
2 tbsp green clay (in 3 lb oils)
peppermint, mint bergamot, rosemary EO blend + lavender FO @ 5%

The last time this happened I rebatched because at least then it would look intentionally lumpy and rustic. Thinking about that route this time too.

 

[DeeAnna]

I am pretty sure your problem is adding the milk powder to your oils. It really needs to go into water, not oil, to properly rehydrate.

 

[amd]

Maybe too much buttermilk powder? I have never used it in soaping, but in cooking it is very concentrated and doesn't need much to dilute it. So if you're putting in 1/4 cup powder plus 2 tbsp. clay, it may be too much powder. I thought I had read somewhere to use buttermilk powder the same PPO rate as clays (1 TBSP PPO), but I should let someone who has actually used it chime in. As I said, I've only used it in cooking and read about for soaping.

Side note: When I add clay to my soap, I reserve a good bit of my liquid (before adding NaOH) and mix it with my clay to get rid of lumps. Or I add my clay directly to my water before adding NaOH. You may want to consider adding a bit of liquid to the buttermilk powder to reduce the powder lumps.

 

[rainycityjen]

I am pretty sure your problem is adding the milk powder to your oils. It really needs to go into water, not oil, to properly rehydrate.

I've added goat milk powder directly to oils before - is this true for all milk powders? I hope so because then I can just change my method and get better results from all of them.

Maybe too much buttermilk powder? I have never used it in soaping, but in cooking it is very concentrated and doesn't need much to dilute it. So if you're putting in 1/4 cup powder plus 2 tbsp. clay, it may be too much powder. I thought I had read somewhere to use buttermilk powder the same PPO rate as clays (1 TBSP PPO), but I should let someone who has actually used it chime in. As I said, I've only used it in cooking and read about for soaping.

Side note: When I add clay to my soap, I reserve a good bit of my liquid (before adding NaOH) and mix it with my clay to get rid of lumps. Or I add my clay directly to my water before adding NaOH. You may want to consider adding a bit of liquid to the buttermilk powder to reduce the powder lumps.

Ah, I had been going by some thread on SMF saying to base milk powder usage on the amount of water in your recipe (the amount of powder you would need to make milk from that amt. water.)

Seeing as how many people dilute their milks with water anyway, I could have been more conservative. And adding the clay unwatered probably did not help.

 

[Obsidian]

IMO, all dry ingredients need to be hydrated before they get added to oils. I tried adding dry milk powder to batter once, ended up with little brown burned bits of powder all through my soap.
Now I add all my powders to water before blending into the oils, no more lumps or spots.

 

[DeeAnna]

I rehydrate milk powder in water (or fluid milk or any other water-based fluid is called for in the recipe) after one experience with the fine bumps you describe. I also stick blend the mixture well, give the mixture some time to rehydrate before use, and finally use a strainer when pouring the rehydrated milk into my oils. Not had a problem since then.

Some types of milk powders are very fine and quickly soluble in water. They may not form the bumps you describe even if mixed into oils -- once they see the water in the lye solution they will dissolve quickly. But some milk powders are coarser or less soluble or whatever. They need time, good mixing, and water to rehydrate properly ahead of time so they don't make those bumps. I don't sweat over which one might be okay in oil and which might not -- I just rehydrate in water, blend well, strain before use, and so far the problem has been solved for me.

"...base milk powder usage on the amount of water in your recipe..."

Yes, that is what I do, but you don't HAVE to do this. You can use more, as long as you can get the powder rehydrated. I just choose to use enough milk powder so the water in my recipe is basically reconstituted "normal" milk.

 

[rainycityjen]

Thanks DeeAnna! Very good to know as I have a LOT of buttermilk powder and keep hearing it's a lovely additive. Just needed to get it right.

 

[Arimara]

Did you stickblend the buttermilk into the oils before adding the lye solution? I haven't had the issue you have yet so I might make another buttermilk soap and see.

 

[DeeAnna]

I re-read your original post, did a little more thinking, and I want to also mention your problem could be stearic spots. Would be nice if you could post a pic -- that would be really helpful.

For me, stearic spots are the most obvious if I use a wire cutter to cut my soap. They don't show up when I use a blade to cut or plane the soap. The stearic soap is very slightly harder than the rest of the soap, and the wire floats around those harder bits, leaving a slightly bumpy surface. A blade cuts right through, leaving a flatter surface. Stearic spots don't have any effect on how the soap behaves during use. The stearic soap bits seem to wear away evenly as the bar is used at the sink or in the bath.

I made the soap with bumps from powdered milk before I had a wire cutter, so I can't tell you if "milk bumps" do the same thing as stearic spots when the soap is cut with a wire cutter. The soap looked fine after being cut with a blade, but that's the same as a soap with stearic spots. The problem showed up as I was using a bar at the sink. The milk bumps are apparently not very soluble in water, so as the soap bar was used, it developed a slightly rough surface. Not scratchy rough, just a pebbly texture. It wasn't horrible or anything, but I didn't like it and I didn't want a repeat batch. I couldn't for the life of me figure out what I'd done differently, until I realized it had to be the powdered milk and how I had handled it when making this soap.

 

[rainycityjen]

Did you stickblend the buttermilk into the oils before adding the lye solution? I haven't had the issue you have yet so I might make another buttermilk soap and see.

I whisked the crap out of it but didn't SB. It was smooth to the eye before I blended in. But possibly not fully hydrated anyway.

 

[Arimara]

A stickblender would have been more efficient than a whisk. A minute or two of that would have blended the powder way better than a whisk could with less of a an error margin. But, again, I made it once and would have to do so again. I could make a batch tonight when the little one is asleep to verify. I want to use up my PKO anyway.

 

[rainycityjen]

By the way here is a pic. The spots are smaller and more frequent than stearic spots I've seen.

 

[Arimara]

I spilled some of my batch on the kitchen table but I made some soap using 2.5 tbsp of buttermilk powder (that is a bit much in my opinion, especially since I used goat's milk XD). I will see how it is in the morning, when I can clean the mess up with less issue.

 

[DeeAnna]

Thanks for sharing the photo, but I do have to say it's still hard for me to say for sure. I think it's interesting that the spots do not go all the way to the edge of the soap; they stop maybe 1/4" from the edges. They also don't seem to be as common in the darkest green areas. That actually makes me lean more toward thinking they're stearic spots than "milk bumps" (wish I could think of a better name!) since the stearic spots are going to be related more to the places in the soap where it heated up, gelled, and then cooled slowly. But I could certainly be wrong.

 

[rainycityjen]

Hmm. Totally possible! Too bad either way, I really dislike the effect.

 

[ngian]

It reminds me somehow of the texture that oatmeal flour gives me to the soaps I use it. So I'm thinking it might be more on the "non-hydrated buttermilk powder" reason for this phenomenon.

It might also be great spots from which soda ash can appear while curing, making this phenomenon even more intense.

In the green clay portion of soap paste, it might not be very intense because of the probably more stick blending time you used so as for the clay to mix well also, leading to a better mix of all the ingredients.

As far as it concerns the stearic spots, I'm used to see them more concentrated (in bigger areas) in a soap surface such the one below:

 

[DeeAnna]

That sometimes happens, Nikos. I've seen that look in some of my shave soaps.

Stearic spots can also be smaller and more evenly distributed than that. Here's an example of one of my soaps that shows smaller stearic spots. This soap was cut with a wire cutter. If I passed it over my planer or if I had cut it with a knife, the spots would be almost undetectable. In this photo, I've sharpened the fine detail to make the spots easier to see -- they look softer and less obvious in real life.