Troubleshooting CP soap results

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Arlo

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Five days ago I made a small batch of coffee soap using a 1 lb silicone mold, first time using this mold. To ensure it went through gel, I placed in on a thick towel which I in turn placed on a heating pad turned to high, then covered the soap with cardboard and the towel. The result is what you see in the picture: the color is lovely, i.e. just what I'd hoped for, but four of the six bars have discoloration at the bottom. I'm guessing it's related to the heat. Any input on what might have happened? Thank you.
Coffee Soap.jpg
 

DeeAnna

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My guess is a bit of overheating, as you thought. I vote for less time with the heating pad on high.

Saponifying soap naturally heats up all by itself if given a chance, but the warmth travels from the inside of the loaf to the outside surfaces. Sometimes the outer surfaces of the soap don't get quite warm enough to gel.

This happens most often to my soap in wintertime when my house is in the upper 60s Fahrenheit. (I live in Iowa, USA) so I might set the mold on a bath towel and cover the top with another bath towel or a cardboard box. That usually works fine for me.

The main reason for adding external warmth is to keep those outside surfaces warmish enough. That's all. There's no real reason to warm the soap all the way through to the middle with your external heat source -- the saponification reaction can heat the center of the soap without any outside help.

In summer, my home is in the upper 70s to low 80s F. I only need to lightly cover the soap with a paper towel or sheet of waxed paper to keep the dust off. That is usually enough to cause my soap to gel completely through.

Outmoded ideas about heating soap were often based on the idea of "baking" the soap all the way through, but that caused more problems than it solved.
 
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I have always had to force gel with my recipes and used heating pads but never used them on high, normally on low or medium, and not directly placed under the mold. I used HDPE molds placed in low plastic crates. I am guessing you overheated the bottom.
 

TheGecko

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I concur with @DeeAnna...hot spot on the high heating pad, looking like it was getting hot enough to start separating.
 

Arlo

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Thanks! I was surprised it turned out so nice. Glad I did a small batch though as I learned a lot about heating pads!
 

Becky1024

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Thank you all. Lesson learned, I'll keep the heating pad on low, if I use it.
You might want to try the heating pad on top of the loaf too. Just cover the soap with some plastic wrap and put the heating pad on top. That works better for me, seems to heat the loaf more evenly.
 
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Why does the dark rectangular soap seem to have a white skin around it? I have never seen that before. My soaps that turned brown from vanillin (by design) went brown from the outside in. Your soap looks lovely. I would love to know how you got that white rim.
 

Arlo

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You might want to try the heating pad on top of the loaf too. Just cover the soap with some plastic wrap and put the heating pad on top. That works better for me, seems to heat the loaf more evenly.
This is a good tip, thanks!

Why does the dark rectangular soap seem to have a white skin around it? I have never seen that before. My soaps that turned brown from vanillin (by design) went brown from the outside in. Your soap looks lovely. I would love to know how you got that white rim.
That's a really good question. If it was just the top, I'd think soda ash (even though I sprayed with alcohol plus it doesn't really look like soda ash). But it goes all the way around. I have no idea why. I poured three little round ones with extra batter and they too are white although I don't know what the inside looks like.

Really good looking soap there -- good job! Did you add a scent? My trick with unexpected results is to call it 'rustic.' :)
Thanks! Yes, I'll call it rustic... No fragrance. I'm a little gun shy with scents ever since I had to leave a soap on the deck to cure for months because it was too strong to be in the house. And then there are those I've tried that ended up having no scent at all. I just haven't figured it out yet.
 

earlene

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Why does the dark rectangular soap seem to have a white skin around it? I have never seen that before. My soaps that turned brown from vanillin (by design) went brown from the outside in. Your soap looks lovely. I would love to know how you got that white rim.

That's a really good question. If it was just the top, I'd think soda ash (even though I sprayed with alcohol plus it doesn't really look like soda ash). But it goes all the way around. I have no idea why. I poured three little round ones with extra batter and they too are white although I don't know what the inside looks like.
When I enlarge the image, it looks a bit translucent around that lighter upper surface edge and makes me think it looks like when I pour batter at either emulsion or thin trace and the outer edge has some thinner soap clinging to the upper sides of the mold, & when removed from the mold often looks like that. Sort of like the outer edges of candy poured on a baking sheet becomes more translucent than the thicker center, and also more brittle.

Is that what it is? Even if not, I suspect once you bevel the soap (if you do) that will remove the lighter edge.
 
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This is a good tip, thanks!


That's a really good question. If it was just the top, I'd think soda ash (even though I sprayed with alcohol plus it doesn't really look like soda ash). But it goes all the way around. I have no idea why. I poured three little round ones with extra batter and they too are white although I don't know what the inside looks like.


Thanks! Yes, I'll call it rustic... No fragrance. I'm a little gun shy with scents ever since I had to leave a soap on the deck to cure for months because it was too strong to be in the house. And then there are those I've tried that ended up having no scent at all. I just haven't figured it out yet.
I'm not sure if you are using essential oils or fragrance oils or both. I get usage rates from Find Free Essential Oil Blends - Essential Oil Calculator .
 

Arlo

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I'm not sure if you are using essential oils or fragrance oils or both. I get usage rates from Find Free Essential Oil Blends - Essential Oil Calculator .
The time I had to cure it on the deck it was a fragrance oil and maybe I used too much. Otherwise, it's been essential oils. I'll take a look at the link you suggest. Thanks!

When I enlarge the image, it looks a bit translucent around that lighter upper surface edge and makes me think it looks like when I pour batter at either emulsion or thin trace and the outer edge has some thinner soap clinging to the upper sides of the mold, & when removed from the mold often looks like that. Sort of like the outer edges of candy poured on a baking sheet becomes more translucent than the thicker center, and also more brittle.

Is that what it is? Even if not, I suspect once you bevel the soap (if you do) that will remove the lighter edge.
Well, I'm not sure I really understand what you're saying (!) but the white surrounds the entire loaf so beveling won't get rid of it. Just like the round one at the top of the photo, the white completely covers everything.
 

earlene

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Well, I'm not sure I really understand what you're saying (!) but the white surrounds the entire loaf so beveling won't get rid of it. Just like the round one at the top of the photo, the white completely covers everything.
I missed that these were pictures of cut bars (or one cut bar). For some reason I assumed it was an uncut loaf. I see now that of course it is a bar and not a loaf. And I can't really see the lighter colored sides, only the solid darker surface and none of the sides, but I will take your word for it. :cool:

You know, it just occurred to me that what you might have is incomplete gel in your loaf because the soap heated from the inside and the bottom, but perhaps not completely on the sides. The bit of lighter color I can see on the edges looks the same color (to my eyes in this light) as the (ungelled?) round soap. I am guessing you did not gel the round soap because gelling vs not gelling coffee soap can give that result.

Here is a coffee soap with a lighter outside, a bit more pronounced than what I see in your photo, but it may explain your soap: Coffee soap problems
 

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