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What makes emulsion loose viscosity?
I made 100g glycerin cream in laboratory scale with :<div>
Water Qsp
Edta 0.1%
Citric 0.05%
Cetearyl alcohol 3%
Emulsifier wax 5%
Glycerin 3%
Parfum 0.5%
Paraffin oil 10%
Preservative 0.8%
Process heating oil phase and water phase separately to 70 °C, start cooling and add oil phase to water phase mixing with 600 rpm
So the emulsion get thick then it loose viscosity.
I want to know the reason of loosing viscosity.
My doubts are :
1)The fast cooling where I take my emulsion far from the heating source just before adding oil to water phase then the 100 grams cream was cooling fast.
2)Reason of mixing after cream getting thick (but I did with other emulsion and they didn’t loose viscosity)
3)there is needed mixing time in hot temperature to get stable thick cream that will not get thinner after thickening.
Also by making after shampoo( hair conditioner )I get very strange curve of viscosity with temperature variation so supposed u is the viscosity, I had as viscosity u(75°C)>u(70°c)>u(49°C)>u(53°C)>u(60°C)
Any explanation from experts please I really thought a lot without reaching convincing answer.
@Perry44 @chemicalmatt @Cafe33 @Abdullah @Pharma @Graillotion @Paprik @ngarayeva001 @ketchito
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16 Replies
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I am having a little trouble following the timeline. But it sounds a little like a phase inversion (for lack of details). This occurs when an emulsion tries to first become a W/O instead of O/W. They manifest as being very thick at first. Typically once you reach a certain point that breaks…and tries to return to O/W which is typically far less viscous.
Again… without a detailed description of what is happening at what point in time… I could be way off.
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Thanks.
For making cream the order is :
1)heating separately oil and water phase to 70°C(Except perfume and preservative)
2)take both oil and water phase far from heat source(cooling start very fast it needs near to 30 min to reach 40°C)
3)start stiring with 600 rpm speed
4) between 50° C and 40 °C emulsion became thick as usual(stiring 600 rpm) .
5)from 40° C or lower emulsion became thinner( stiring 600 rpm without adding preservative and perfume)
For conditioning hair : the chronology of viscosity is in cooling phase.
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You should add the oil nto the water phase while keeping the heat during the entre emulsification process. Only after that, you start cooling (not before). This prevents crystal formation of your high melting point waxes so they can properly mix.
Also, the amount of mineral oil might also be to blame for the viscosity loss. Non polar oils are hard to emulsify. Are you making a massage cream? If that’s the case, then build a more robust interfase to support the mineral oil. If not, then just drop it to 2-3%.
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Actually I have very close formulation with preolatum instead paraffin oil and I did not face a problem actually I got with petrolatum viscous cream. About recristalisation all solids have fusion temperature far from 70 °C then it can not happen. ( today I just do same process described just increasing the speed of stiring and I got better results.)
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I’am not making massage cream however why massage cream use parrafin oil?
When adding dimethicone 350 to cream the viscosity decrease more. Can you guess why?
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It’s either preservative or the emulsifier because the formula os straightforward otherwise. Can you post INCIs, please?
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I did not add preservative and perfume.
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But you have both listed in your formula? What was the emulsifying wax you used? An INCI name would help, but a trade name would be better. As @ketchito said, make sure your emulsifier works well with the amount of oil you’re using (especially the paraffin oil). If you’ve got a lot of oil in there (like 10% paraffin oil), you might need extra stabilisers &/or thickeners to keep things thick after it cools. As @ngarayeva001 suggested, GS+GSPEG100 would work if you kept the formulation unchanged. Like her, I’ve used mineral oil with GS+GSPEG100 lots of times over the years without issue.
The observed viscosity drop at around 40°C might be related to phase separation or incomplete emulsification, particularly if the emulsion hasn’t been given enough time to stabilise during cooling. I’m basing this on [quote] u(75°C) > u(70°C) > u(49°C) > u(53°C) > u(60°C) [/quote] as I think this suggests that the conditioner’s viscosity is sensitive to temperature.
Another thing is phase inversion could indeed be the reason your cream is losing viscosity. Gradual cooling and reducing mixing speed at lower temperatures can help prevent this, along with adjusting the emulsifier ratio to better handle the oil phase. So, make sure the oil and water are properly mixed at 70°C and let the emulsion cool down gradually so you don’t end up with crystals forming or the structure breaking down. Keep stirring gently as it cools. It’s fine to keep mixing at 600 rpm when it’s hot, but once it starts thickening (around 50°C), drop the speed to about 300-400 rpm.
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Thanks a lot for your comment, I wrote full lol but when cream loose viscosity I didn’t add preservative and perfume, about stirring it needs high speed stirring to get good viscosity 600 rpm is low.
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If you keep everything unchanged and use Glyceryl Stearate + PEG100 Stearate (goes under many different trade names) as an emulsifier it will work. It handles non polar oils pretty well. I used it with petrolatum and mineral oil many times.
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What is that emulsifying NF?
You need a high shear mixer for emulsification or you would need to mix for a long time when they are hot.
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Hi,
The HLB required to emulsify paraffin is 10-11, what is the HLB of the emulsifier wax you are using?.
It might also be due to the cooling mixing speed and the propeller you are using. after combining oil to water phase, maintain the rpm and temp for 8-10 min, then turn off heat, switch to an anchor blade and reduce the speed.
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This reply was modified 1 month, 3 weeks ago by Bureta14.
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I fix hlb 10, the solution is as you said from process.
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This reply was modified 1 month, 3 weeks ago by
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