Can't get rid off bubbles in soap

[Lyma]

Hi,
I'm making cold process (40C) soap (90% Olive - 10% Coconut) since the last 5 years.
I making large batches (20kgs) and use big cube molds.
I was always using a painted drill for stirring and never had any issues with bubbles. Except if i was too careless when pooring in the mold or the soap turned too thick when pooring, something quite reasonable.

The last months i've switched to an immersion blender which made stirring much easier and quick. But since then i'm having issues with tiny bubbles in the final soap.
I've tried anything (very light trace, very careful when pooring in mold, changed temperatures, low speed on blending with much hand stirring, tap the blender, tap the mold etc.) but most of the times these bubbles are there. I've also tested that it's not the wire cutter that does this.

When pooring the lye or the additives (e.g. pomegranate juice) in the mixture i see some similar tiny bubbles forming, but i keep on handstirring till they dissapear. I suppose it's not from stirring, because when pooring to mold i see no bubbles going down.
The other weird thing is that the bubbles appear mostly in the inner (warmer) layers of the cube mold. Suppose that we split the big cube in 4 horizontal layers, these bubbles are mostly seen in the middle 2 & 3 layers, while at the upper & lower layers there are only a few or not at all.

As you see in the pic below, the one on the left is from the upper layer of the mold while the other two are from the middle ones. The soaps from the bottom of the mold, have also no bubbles.
Does anyone knows why this is happening? It's really important for me to understand the process, although it may not be so serious. :0

 

[lsg]

Sometimes air can get trapped under the bell of a stick blender. I have seen tutorials in which the lye/liquid mixture is poured down the side of the stick blender, into the oils. This is supposed to help prevent bubbles.

 

[earlene]

Is the pomegranate juice carbonated?

Can you show a picture of the immersion blender and tell us the make and model?

 

[Lin19687]

2 things, Do you bang it enough after the pour?
Check the stick blends. I had one that the blade was bent a little and it made all sorts of tiny bubbles

 

[Lyma]

Sometimes air can get trapped under the bell of a stick blender. I have seen tutorials in which the lye/liquid mixture is poured down the side of the stick blender, into the oils. This is supposed to help prevent bubbles.

Yes i've read that too. I try to do this, but because of it's big volume, it's really difficult to avoid bubbles while pouring lye to the oils. However i can't see them after light trace and when pouring to mold.

Is the pomegranate juice carbonated?

Can you show a picture of the immersion blender and tell us the make and model?

No the juice is not carbonated.
I use that kind of blender

2 things, Do you bang it enough after the pour?
Check the stick blends. I had one that the blade was bent a little and it made all sorts of tiny bubbles

I bang it as much as i can. The blends seem fine.
If the problem was the blender and during stirring, why the bubbles appear mostly on the middle of the mold where the temperatures are higher and the soap softer?
Also if you can see at the pictures on the inside of the bubbles, are formed something like tiny crystals.

 

[earlene]

So if you go back to the painted drill stirring method of blending you would have no bubbles? You said it was slower, right and it took more time to do the blending?

Could it be the SB is too powerful? What is the wattage? Does it have multiple speeds or powers? If yes, which speed/power are you using? I looked for blenders that look like what you've got and they all seem extremely powerful, and also quite expensive. But since you are in Greece and I am in the US, I doubt I found the brand and model you have and therefore am only guessing that it is super powerful.

As to why the bubbles would only be in the center part of the mold, it is the nature of air bubbles to rise in liquid. It is also the nature of bubbles to expand as they rise. That would explain why they are bigger in the center portions of the soap mold.
Perhaps there are tiny bubbles that you don't see when pouring, but they expand as they rise in the heating up soap, as is the nature of air bubbles.

 

[Lyma]

So if you go back to the painted drill stirring method of blending you would have no bubbles? You said it was slower, right and it took more time to do the blending?

Could it be the SB is too powerful? What is the wattage? Does it have multiple speeds or powers? If yes, which speed/power are you using? I looked for blenders that look like what you've got and they all seem extremely powerful, and also quite expensive. But since you are in Greece and I am in the US, I doubt I found the brand and model you have and therefore am only guessing that it is super powerful.

As to why the bubbles would only be in the center part of the mold, it is the nature of air bubbles to rise in liquid. It is also the nature of bubbles to expand as they rise. That would explain why they are bigger in the center portions of the soap mold.
Perhaps there are tiny bubbles that you don't see when pouring, but they expand as they rise in the heating up soap, as is the nature of air bubbles.

To be honest i didn't make a batch with the drill again, as it had a damage and then i bought the blender. The blender is 800W and has multiple speeds. It's more powerful than the drill but i don't work it in the maximum. After i saw the bubbles i've tested it at the lowest possible speed together with hand stirring, but again the bubbles were there.
The only difference i observed, is that with the blender, althought it's much poweful, does not make the mixture spinning around quickly and evenly as it did with the dril. I suppose due to the bigger surface of the blends. So maybe the problem is at the time i pour the lye to the oils. Before it was spinning all the mixture quickly, but evenly, when i was pouring the lye and didn't see many bubbles forming. Now with the blender i can obviously see them when i pour the lyem but i was supposing they disappear till trace. The problem with oilve oil mixture is that it's quite thin in the beginning, comparing to a mixture of saturated oils, so much more prone to bubbles.
I will do two last tries with the blender, one with no stirring at all when pouring the lye to oils, and one with full speed, and see any if i have any difference.

Two questions:
1. After these tiny bubbles are trapped in the mixture after pouring lye, is there any way to get them out when pouring into the mold? I've tried a narrow strainer, but again nothing. I banged the mold, or hand stir with a spoon inside the mold, but the damn bubbles can't move. They are so tiny that you can't even see them. And while in the mold they become larger as you said due to high temperature.
2. The crystals i see inside the bubbles what exactly is it? Is it trapped NaOH that didn't manage to dissolve, or is something of not to worry about?

 

[cmzaha]

I will go a different direction here, you mentioned it happens in the middle of the mold so maybe you are getting a slight overheating issue, the beginning of a volcano resulting in alligator teeth. If using a lye concentration of 33% or lower I would up the lye concentration, resulting in using less water/liquid and soaping cool. Just my take on this and the juice could very well add to the overheating issue.

 

[earlene]

Two questions:
1. After these tiny bubbles are trapped in the mixture after pouring lye, is there any way to get them out when pouring into the mold? I've tried a narrow strainer, but again nothing. I banged the mold, or hand stir with a spoon inside the mold, but the **** bubbles can't move. They are so tiny that you can't even see them. And while in the mold they become larger as you said due to high temperature.
2. The crystals i see inside the bubbles what exactly is it? Is it trapped NaOH that didn't manage to dissolve, or is something of not to worry about?

1. I don't know really. I struggle with that myself sometimes. Even with small batches. I don't make anything as large as yours. The biggest batch I've made was less than 3000 grams, but I was just lucky and didn't get any bubbles at all in the soap. With some I do get bubbles and all the tapping and pounding of the mold doesn't always get rid of them. For me, I am pretty sure that if I soap too thick bubbles just will not rise to the top and they get trapped inside.

Slow stirring is one way to prevent air bubbles, according to what my research tells me. So it would stand to reason that using the immersion blender on the slowest setting is also the best way to prevent air bubbles. Pouring the lye slowly against a weir or the side of the stick blender or a spatula so that it cannot create more air bubbles is another way. And it is suggested to hand stir the batter gently with a whisk or a spoon to help release bubbles AFTER you quit using the immersion blender and before pouring the soap. Also when pouring the soap, take the same precautions to prevent introducing new bubbles by pouring slowly against a weir, a spatula or a spoon.

2. I really don't know. But I doubt very much that it is undissolved lye crystals. However, if you really suspect that, you should zap test. I did not notice crystals; I just thought those were pieces soap that flaked off during cutting and got lodged inside. If they are actual crystals, then I'd be concerned and zap test.

So, you say this is the very same recipe you have used with the previous stirring method? No changes at all except the blender?

 

[Lyma]

I will go a different direction here, you mentioned it happens in the middle of the mold so maybe you are getting a slight overheating issue, the beginning of a volcano resulting in alligator teeth. If using a lye concentration of 33% or lower I would up the lye concentration, resulting in using less water/liquid and soaping cool. Just my take on this and the juice could very well add to the overheating issue.

I make almost cold process. I just heat it slightly (40 C) to get things a little bit faster. And i'm using 38% lye concentration. I don't thing it's an overheating issue. As earlene said, they are more obvious in the middle, because heat makes them expand.

1. I don't know really. I struggle with that myself sometimes. Even with small batches. I don't make anything as large as yours. The biggest batch I've made was less than 3000 grams, but I was just lucky and didn't get any bubbles at all in the soap. With some I do get bubbles and all the tapping and pounding of the mold doesn't always get rid of them. For me, I am pretty sure that if I soap too thick bubbles just will not rise to the top and they get trapped inside.

Slow stirring is one way to prevent air bubbles, according to what my research tells me. So it would stand to reason that using the immersion blender on the slowest setting is also the best way to prevent air bubbles. Pouring the lye slowly against a weir or the side of the stick blender or a spatula so that it cannot create more air bubbles is another way. And it is suggested to hand stir the batter gently with a whisk or a spoon to help release bubbles AFTER you quit using the immersion blender and before pouring the soap. Also when pouring the soap, take the same precautions to prevent introducing new bubbles by pouring slowly against a weir, a spatula or a spoon.

2. I really don't know. But I doubt very much that it is undissolved lye crystals. However, if you really suspect that, you should zap test. I did not notice crystals; I just thought those were pieces soap that flaked off during cutting and got lodged inside. If they are actual crystals, then I'd be concerned and zap test.

So, you say this is the very same recipe you have used with the previous stirring method? No changes at all except the blender?

Thank you very much earlene.
1. I tried most of what you suggest.
I do a light trace before pouring, because i don't want to mess with thick soap. (difficult to mold).
I tried really slow stirring with many breaks for hand stirring, and whisk at the end.
I always pour against a weir or a big spatula to prevent bubbles.

The only thing i'm not so careful, is when pouring lye to oils. It's quite heavy (8kgs) and it's difficult to pour it with one hand and hold a weir on the other. And it's that time that i see many tiny bubbles forming at the surface of the mixture.
After 30 minutes of stirring i can't see them at all, and i suppose they dissapeared during stirring, but they appear again when cutting the soap.

I'm positive that temperatures pay big role to the bubbles. Because i remeber when i used higher temperatures, the bubbles were bigger but not so many. And it's quite reasonable because a bubble expands due to heat, and it's also more easy to go to the surface (warm air goes up), than many tiny bubbles at the bottom or the middle of the mold. So maybe cold process makes things more difficult if bubbles are trapped inside soap.

Of course the goal is to avoid entering the bubbles in the mixture.

What surprises me also, is that i do all things exactly the same with older times i was stirring with the drill. But then i didn't saw any bubbles forming on the surface when pouring lye to oils. So i believe that it's important for the mixture to be swirled evenly at all of it's volume when pouring something on it, than to be stable.

Anyway i'm going to focus on that stage of pouring lye to oils in combination with stirring speed and different temperatures and see the results.

2. I don't thing also it's undissolved lye. It's just so small to zap test it, but i give it a try.

 

[DeeAnna]

Have you tried letting the mixture just sit quietly right after pouring the other liquids into the fats? The bubbles may remain trapped in the batter if you start stirring right away.

You might try asking Ariane Arsenault of La Fille de la Mer, https://www.lafilledelamer.com/ for help. She might have some tips for you. She makes large batches of soap too and may have encountered this problem before.

 

[Lyma]

Have you tried letting the mixture just sit quietly right after pouring the other liquids into the fats? The bubbles may remain trapped in the batter if you start stirring right away.

You might try asking Ariane Arsenault of La Fille de la Mer, https://www.lafilledelamer.com/ for help. She might have some tips for you. She makes large batches of soap too and may have encountered this problem before.

Thank you DeeAnna for the link. I may contact ger for more information.

I can see them at the surface without moving or breaking apart. Only after i start stirring i can see them gathering at the circled edge of the mixing pot, and then they disappear or that's what i think. It's difficult to be trapped inside the mixture at the beginning of stirring because olive oil is quite thin and runny, especially evoo.
I think if i was making hot process they could more easily brake up. At the time i will focus on the way i pour the lye into oils and the stirring speeds.
At least it's important to be sure for the reason that causes them, and eventually i'll try to reduce them to the minimum possible.

 

[Zoeybean]

Is it possible that the seal on your blender is broke or leaking air into the soap through the shaft?

 

[Lyma]

Is it possible that the seal on your blender is broke or leaking air into the soap through the shaft?

Everything is possible in soapmaking
But i think it's not that. I've checked it and it seems fine.

 

[Lin19687]

So what was the outcome ?
I was scanning over the 2nd page posts and wondered what happpened to this

 

[Lyma]

So what was the outcome ?
I was scanning over the 2nd page posts and wondered what happpened to this

Hi Lin
Well i've made a few batches since then, and managed to reduce them, but they are still there, fewer and smaller, but still there.
I payed much attention while pouring lye to oils and other additives, and also lower the temperatures at 40 C degrees.
Maybe the problem is happening while pouring the soap in the mold. I pay much attention, use a big spatula to reduce the momentum of the soap while dropping, and believe me while seeing the soap in the mold after i finish i see nothing, and think ok i did it.
But next day when i cut it, i still see these tiny bubbles on the hotter parts of the cube. It's really strange and frustrating.

I'll fix my drill to make a batch as the old times, and see if the same thing happens.

 

[Lin19687]

If you are using a drill with a paddle attachment to mix, that may just be it. They would be so small bubbles that you may not see them.
I think the drill goes too fast and gives a bigger air intake to the batter.
I hope that makes sense to you.
Try a small batch like a 1 or 2 pound and see how it does

 

[Lyma]

Hi again,
After many tries, while changing stirrers, ways to pour lye or additives to oils, and ways to pour mixture to mold, i concluded that these white crystal spots appear in the mold withing the 24hour waiting period before unmolding.
After searching on web from other soapmakers who have the same problem, and reading Kevin Dunn's book, i'm sure this happens because of gel phase. And that's why they appear mostly in the middle of the mold while on the surfaces are completely absent.
The dilemma now is to try for a full gel phase or to prevent completely gel phase?
While i believe i can achieve full gel (increase mixing temperatures, good insulation of the mold etc.) i don't know how to avoid partial gel phase. I use cold process (40C), lye concentration 40% and in my last batches i don't insulate the mold.
Of course the mold is quite big to put in the fridge.

I completely dislike partial gel. But if i try for a full gel phase, then the white spots i suppose will increase to the whole block mold and not only in the middle.
Can anyone give me any advise?