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Getting along with SCI
In the context shampoo bars, Belinda Carli says to melt SCI slowly at about 50-60 C. She also warns that it takes time. Susan Barkley-Nichols uses a double-boiler and melts SCI into CAPB. So hers is at a significantly higher temperature, and melts faster with no apparent problem.
I am having a terrible time finding any information on best temperatures for SCI. Most of the guidance I’ve found says to heat it slowly without much detail on what that means either for temperature and/or time. I’ve spend months on this and I just don’t understand why SCI would need to be processed only at very low temperatures.
I assume there is an upper limit to how hot we’d want SCI to get. I don’t want to incinerate it of course. But do I really need to keep it at 50C to melt it? Even 100C? and why?
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12 Replies
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I used SCI only in solid (anydrous) formulations, such as bar shampoos and so on, so I end up adding the powder in the oil phase (while heating) and mixing everything until it completely incorporates.However, we have an ingredient of INCI Sodium Lauroyl Methyl Isethionate (Iselux® Flakes by Innospec) that presents in its technical material a high indication for cleansing systems, mainly transparent ones. Its melting point can be a little high and present some difficulties, but in general if you add little by little, waiting for it to melt before adding more, it can work. I have also only used it for anhydrous systems, so my main recommendation would be to check with your supplier for the most appropriate procedure.Also, in a quick search I found that the SCI flash point is +/- 96 ºC. I don’t know if it’s correct, but I wouldn’t recommend reaching 100ºC as you said
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On an unrelated note, SCI is starting to become scarce. One of my clients has been working hard to get stock and has been told to expect additional shortages.
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I dont know anything about shampoo bars but in my liquid shampoo i heat water to 70 or 75 then add sci, mix a for a couple minutes and its nice and dissolved. But if you leave it out to cool for too long after that point it will start to become solid again.
@Microformulation thats sad
to hear about the shortage, i love the stuff, i should order more now i guess. -
GeorgeBenson said:I dont know anything about shampoo bars but in my liquid shampoo i heat water to 70 or 75 then add sci, mix a for a couple minutes and its nice and dissolved. But if you leave it out to cool for too long after that point it will start to become solid again.Hey mate, what do you mean by “but if you leave it out to cool for too long after that point it will start to become solid again” ?
Do you mean like you need to proceed with the formulating or ? …
Why am I asking - It happened to me that it precipitated …
Thank you!
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So do suppose that the reason it’s recommended to melt it low and slow is because of this putative flash point?
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@Paprik i set aside maybe a fifth if the formula’s total water content. Then i proceed to mix the other surfactants with the majority of the water. Then I heat up the small portion of water and dissolve the sci. Then i mix that sci water back into the main batch of water and surfactants. Doing this gives me a clear and stable batch of shampoo every time. But if i were to leave that sci water out by itself for 20-30 minutes it would turn into a cloudy pasty mess. I’m not sure why this works but it works every time.
now if i could just figure out how to get cationic guar from precipitating out i would be a happy man…but i gave up on that a long time ago.
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@GeorgeBenson .. oh I see .. thanks for sharing. I actually always dissolved SCI in Cocamidopropyl Betaine. But I haven’t done a lot of stability tests.
However I love SCI and the idea to have it in facial cleanser or so … So will definitely try it
Regarding the guar gum, is it Guar Hydroxypropyltrimonium Chloride? I had never issues with it
It went always straight to the water and after acidifying it a bit it hydrated and no problem.
When are you adding it? If you add that before last ingredient containing water it might separate as the additional water might not be “used” by the gum?
(I also always use medium shear - sawtooth disc stirrer).Hope this could help a bit? Good luck and happy formulating.
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@Paprik yes i am using guarcat from lotioncrafter and would use a glycerin slurry and neutralize it. Maybe i will try it again though, it’s been a while.
So for a shampoo for instance you would just add it straight into the water after the surfactants and any other water-containing ingredient, and mix? -
Not sure where the information about the flash point came from but on the SDS I have it is listed as having a flash point of greater than 93 C. This is the cutoff value for flammable liquids so it just means it is not a flammable liquid.I usually just melt it around 70 to 80 C with the CAPB which works well. -
The good thing about Guar HPTCh is that you don’t need to slurry it. It goes straight into water. And you don’t neutralize it, you acidify it (you bring the pH down).
I am using it so far only in conditioner, but yes, I would add that after all water-containing ingredients.
So it hydrates with all water available. Otherwise it will swell only with some water and if you would add another water-containing ingredient it would not get “grabbed” by the gum as it is already hydrated. And that could result in separation.I hope it makes sense? Maybe someone will correct me. .
UPDATE:
https://cdn.shopify.com/s/files/1/0026/8317/5001/files/TIB_VC-993_N-hance_3215.pdf?v=1606338576
Hmmm .. I checked that ingredient on LotionCrafter and here’s how they recommend to use it -
* temperature/mixing conditions o cold processable, but tolerant of hot processing
* add the polymer to the vortex of well-agitated water until dispersed. o continue mixing and adjust pH to ~5.5 and continue mixing until particles dissolved
* add surfactants in order of ionic character, beginning with non-ionics, amphoterics then anionics to avoid incompatibility. Add the remaining formula ingredients, adjusting pH and viscosity if necessary. -
Yeah you know it actually works fine for me
in my conditioner as well. I will try it again in my shampoo using these different methods and hopefully it works this time. Thanks! -
ozgirl said:Not sure where the information about the flash point came from but on the SDS I have it is listed as having a flash point of greater than 93 C. This is the cutoff value for flammable liquids so it just means it is not a flammable liquid.I usually just melt it around 70 to 80 C with the CAPB which works well.
Sorry, my bad. I forgot to mention the SDS i found. I also took a look internally at the technical material we received, which indicated >96 ºC
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