What makes this happen on stain sticks?

[Feelin' Soapy]

I've made lots of these and sometimes they come out with these super hard edges, and sometimes they don't. Always the same recipe (100% CO, 2% limonene, 0 SF, 38% lye concentration). I put them in the fridge right after pouring. I'm thinking the darker centers are where it's gelled?

It's always a tough call when to unmold and cut because a little too long and they're like concrete, too soon and they fall apart or mush out. It's a small window of "just right." Would adjusting the lye concentration help?

 

[DeeAnna]

The darker centers are indeed due to partial gel.

A 100% coconut oil soap will get hot while saponifying. I normally try to discourage that by soaping cool and using around 28-30% lye concentration. This particular recipe is one of the few times I'll use that much water.

I know the common wisdom in small-scale soap making says to put saponifying soap in the fridge or freezer to cool it down. For one thing, I can't fathom why one would want to put a hazardous material in a place that contains food.

Not to mention the fact that non-moving air, even if it's cold air, is a really inefficient way to cool something down. Better option: Put the mold on a few cans of soup and train a fan to blow room temperature air over, around and under the mold.

Don't cut soap according to time; cut soap when it's ready to be cut -- when it yields to a gentle finger press but doesn't dent. Like refrigerator-cold mild cheddar cheese. If it dents like cold cream cheese, it's not ready. If it feels hard like Parmesan cheese, it's too hard.

In my experience, a 100% coconut oil soap might be ready to cut in 4-6 hours or it might be ready the next day. If you do cut at 4-6 hours, be sure to wear gloves to protect your skin because the soap won't be quite done saponifying at that point.

 

[Feelin' Soapy]

The darker centers are indeed due to partial gel.

A 100% coconut oil soap will get hot while saponifying. I normally try to discourage that by soaping cool and using around 28-30% lye concentration. This particular recipe is one of the few times I'll use that much water.

I know the common wisdom in small-scale soap making says to put saponifying soap in the fridge or freezer to cool it down. For one thing, I can't fathom why one would want to put a hazardous material in a place that contains food.

Not to mention the fact that non-moving air, even if it's cold air, is a really inefficient way to cool something down. Better option: Put the mold on a few cans of soup and train a fan to blow room temperature air over, around and under the mold.

Don't cut soap according to time; cut soap when it's ready to be cut -- when it yields to a gentle finger press but doesn't dent. Like refrigerator-cold mild cheddar cheese. If it dents like cold cream cheese, it's not ready. If it feels hard like Parmesan cheese, it's too hard.

In my experience, a 100% coconut oil soap might be ready to cut in 4-6 hours or it might be ready the next day. If you do cut at 4-6 hours, be sure to wear gloves to protect your skin because the soap won't be quite done saponifying at that point.

Thank you, thank you, for so much helpful info on this! I will definitely cut the lye concentration way back and try your cooling method instead of the frig. I began putting it in the frig after one batch cracked and bulged from internal heat.

I usually soap stain sticks at about 90, but I will drop that down to 80 next time. I'd assumed that since I wasn't doing any swirling or anything fancy, it didn't matter doing it a little warm.

Judging the time to unmold and cut these bars has been difficult for me because they tend to get very hard around the edges while still being too soft in the center. First time I made them I waited about 4 hours, and they were so hard I had trouble cutting them.

I'll be making more soon and will put all your advice to use. Thanks again!

 

[Ford]

Hi, would using individual cavity molds work also?

 

[AliOop]

Hi, would using individual cavity molds work also?

That's what I prefer so that there isn't any issue with timing the cut, volcanos, etc.

 

[not_ally]

@AliOop, I took your advice (to use cavity mold) on this, and was glad. Mine did overheat/bubble over a little but were fine in their little cavities, did not make a mess by bubbling over anywhere else, and came out of the cavities easily. They are not pretty, but with stain sticks who cares!

I was also making two different types, tallow and coconut, so it made it easy to identify them (tallow in square cavities, CO in round) so that I can figure out if one works better than the other in use (I didn't want to use colorants in case they made the stain sticks stain!)

 

[Feelin' Soapy]

Cavity molds are a great idea for this. I just ordered some
@AliOop Does your other sage advice still hold for cavity molds? 28-30% lye concentration? Cool with fan blowing?

 

[AliOop]

Cavity molds are a great idea for this. I just ordered some
@AliOop Does your other sage advice still hold for cavity molds? 28-30% lye concentration? Cool with fan blowing?

Great question! With cavity molds, I use my typical 40% lye concentration. I've never had any overheating in cavity molds so have never needed to elevate them or have a fan blowing on them.

I only heat the CO to about 90F, since it is fully melted at 76F. Then I pre-mix the d-limonene into the oils, pour in my room-temp MB lye solution, blitz for a just few seconds with the SB to reach light trace, and pour. Easy-peasy!

 

[Feelin' Soapy]

@AliOop Thank you again! Will give this a try when the molds arrive

 

[Feelin' Soapy]

So my new cavity molds arrived and I made a batch yesterday. 40% lye concentration, soaped at about 90F. All went well with only one surprise: it took about 6 hours to unmold!
Can anyone (@DeeAnna ? @AliOop ?) explain why this same recipe in a loaf mold unmolds in about 2 hours and becomes too hard to cut if I wait much longer, but in cavity molds they're still "cheddar cheese" soft at 6 hours? Is it because they don't hold so much heat in the centers?

 

[DeeAnna]

So my new cavity molds arrived and I made a batch yesterday. 40% lye concentration, soaped at about 90F. All went well with only one surprise: it took about 6 hours to unmold!
Can anyone (@DeeAnna ? @AliOop ?) explain why this same recipe in a loaf mold unmolds in about 2 hours and becomes too hard to cut if I wait much longer, but in cavity molds they're still "cheddar cheese" soft at 6 hours? Is it because they don't hold so much heat in the centers?

It's all about how warm the soap gets during saponification.

A single mold filled with all of the soap batter will get warmer than the same amount of batter in multiple cavity molds. A loaf mold has less surface area than individual molds, so soap in a loaf mold doesn't lose heat as fast. The soap gets warmer overall.

Soap that gets warmer during saponification (up to a point) tends to be harder sooner than soap that doesn't get very warm, assuming all other things are equal. So the hardness of soap in a loaf mold >> soap from a slab mold >> soap in individual cavity molds

 

[Feelin' Soapy]

Thank you @DeeAnna for the detailed explanation! It makes total sense.

I just wish I'd figured that out before making that batch at 6pm and having to stay up late to unmold and cut each bar in half

There's always more to learn and unexpected surprises no matter how many years I've done this! Keeps it interesting

 

[DeeAnna]

Thank you @DeeAnna for the detailed explanation! It makes total sense.

Glad I could help. Maybe insulate the molds with a thick towel next time? Or even use a heating pad to add a little extra heat so they stay warmer?

Now that I've given this sage advice, I confess I don't always follow it. I sometimes have extra soap batter that I pour into small cavity molds. But I have yet to remember to keep these molds warm while they saponify. Maybe someday I'll get it right!

 

[Kiti Williams]

I bought a mold that had individual rectangular shape 4"X1"X1" size. I used it to make my stain stixs. They were hard in under 2 hours and unmolded. IDKW yours didn't harden up.

 

[Feelin' Soapy]

@Kiti Williams That is a mystery indeed! Mine harden in under 2 hours in the loaf mold, but not the individual cavities.

 

[Kiti Williams]

@Feelin' Soapy If it is the same mix, maybe the lye is to blame. Could yours be a lessor purity? Maybe weather/barometric pressure is to blame.

 

[Feelin' Soapy]

I'm very confident about the quality of my lye. And previous posters in this thread say it takes 4 to 8 hours for their SS on cavity molds as well. It's just one of those things, and I'm fine with giving it the time it needs.

 

[Kiti Williams]

I'm very confident about the quality of my lye. And previous posters in this thread say it takes 4 to 8 hours for their SS on cavity molds as well. It's just one of those things, and I'm fine with giving it the time it needs.

It's weird, though.....