Transparent soap with 40% TFM possible?

Hi all. 

I am trying to make transparent soap with 40% TFM. 

Ingredients : Stearic acid, lauric acid, castor oil, NaOH, water, propylene glycol, sles 70%, capb, peg 400, triethanolamine. 
Process: I add the sles to the oil phase, heat it and add hot lye solution. After saponification, i add the solvents one by one, keep stirring for 10-15 minutes with constant heating. The solution now is transparent. I pour it in the mold. When it cools down, it gets cloudy.. not completely opaque. The edges are clear. 

Where am i going wrong? Should i be using different solvents? Should my process be different? Please help!


  • @Padmavathi Perhaps your fatty acids or castor oil are not being completely neutralized, and either being emulsified by surfactants or just migrate to the center and crystalize due to cooling down. Also, cooling rate could have an effect on transparency.

  • Hi @ketchito ! If i saponify my oils without the surfactants, i am getting a very hard mass. I am not able to dissolve it in the surfactants then. That is why i mixed both.
    And for the cooling part.. i just pour it in my mold and leave it on the table overnight. Where i am, the temperature is always on the hotter side; so i know it is not cooling down rapidly. 

    I can probably try to saponify under closed conditions, giving it more time than i do now. 
  • @Padmavathi It's ok that you mix both saponified oils with surfactants. My point is that you might not have used enough NaOH, so part of the fatty acids were not converted into soaps themselves, but rather stayed as fatty acids. So, when you mix them with your synthetic surfactants, you'd emulsify them, similar to when you mix cooking oil with water and detergent. Some companies actually leave part of the fatty acids unsaponified, since they give humectancy and there's less free alkalinity in the system, but the product is of course not transluscent. 

    By cooling rate I was thinking more about trying to cool the soaps rather fast to avoid tight packaging of surfactants (similar to when you make glass, which is cooled fast so it stays as an amorphous inner structure that lets light pass without scattering). 
  • @ketchito I calculated the NaOH needed for my oils, but used little more than that, just to be safe. I avoided any super-fating as it might affect the transparency. 

    For the cooling, do you suggest i keep it in the refrigerator? 

    Other doubt... my formula is for 120g, to get 100g soap after evaporation loss. If 20g water has not evaporated, will that affect the clarity? Or if i let too much water evaporate, will that affect my clarity? I am not sure how much water is lost, as it is difficult to get the exact weight of my soap. After i pour it in the mold, there is so much wastage in the vessel, stirrer, spatula and seive. If i try to weigh it with the vessel before pouring in the mold, it hardens so quickly. Is that hardening due to excess water loss? 

  • @Padmavathi Yes, you can put one sample on the fridge just for testing, to see if cooling rate here is an issue.

    Also, maybe you can make a sample without Castor oil, since it has triglycerides, which need to be broken down first to have free fatty acids for saponification. Again, just as a test.

    Water loss could affect clarity, although it might not be the issue here. Just to be sure, you can make another test using a bit of excess water to see if clarity improves.
  • @ketchito I will try it out. Thanks a lot :)
  • @ketchito Hey! I did the whole process, covering the vessel. I covered the vessel with aluminium foil, leaving a small gap for steam to escape. It worked. My soap is clear! 
    And the soap is 100g approx (formula was for 120g). The water loss was as expected. 
    Thanks for your inputs :) 
  • @Padmavathi I'm glad you managed to make it clear. Good luck!
  • I covered the vessel with aluminium foil
    Do NOT do this. NaOH + Al -> NaAlO2 +H2. BOOM!
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • @Belassi ; I added the lye solution slowly to the oils with constant mixing. After I poured the whole solution, I covered the vessel with foil. So, will there have been NaOH to react with the aluminium foil? 
    But, never thought of this at all! OMG!
  • Use plastic. Aluminium will react with soap.

    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • @Belassi ok! thank you :)
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