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When to add ~25% cold water in this emulsion?
In a simple LGN emulsion
1% BTMS active
3% cetearyl alcohol
Water
When water is heated to 90°c, then BTMS is added, then melted FA is added and homogenized for 5 minutes.
adding ~25% cold water to this to cool the batch faster was reducing temperature ~15°c.
Now when should i add this 25% cold water?
A: when batch is hot(80-90°c) to reduce temperature to (65-75°c)
B: when batch is a little cold (~65°c) to reduce temperature to (~50°c)
C: below 50°c to reduce temperature to 30-35°c.
Note: I have noticed that in the batches that we have added cold water earlier, they are a bit thicker( dont have viscometer, just feel during use).
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8 Replies
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I’d add it in the phase B, since you need to give your emulsion time to build some identity, so, when disturbed, it can use its “memory” to recover its structure. Usually, cooling down water is pushed inside the lamellar structure which swells, but if your structure is not formed yet, then that water will remain as free water or maybe even hydrating some free fatty alcohols (which might explain the high viscosity you see when adding at high T, but the stability and final texture might suffer).
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Thanks
At what temperature do structures usually form?
Currently i make two emulsions.
BTMS+ FA which is heated to 90°c.
SLS+FA which is heated to 60°c.
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At the emulsion temperature, you ensure there are enough colisions and energy…it’s like you have all the instructions then to organize themselves. Some organization occurs here, but since there’s quite some free energy, there’s also some exchange of molecules. It’s during cool down where the main arrangement happens. That’s why shear here is not advisable (would you shake the table while playing jenga?). I always take between the end of the emulsion process and around 55-60°C as the time where “the baby” learns how to walk. From then on, some high mixing could happen (like in UL’s patent), but shortly, and not so low in T so the emulsion has time to recover in case there’s some disturbance.
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So it is better to take a break from high shear between 55-60°c?
Is it 55-60°c because of melting point of fatty alcohol or they don’t have any connection?
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If you emulsify at 80°C, then after that and till around 55-60°C, you should remove high shear. In fact, you wouldn’t need high shear after the emulsion. Sometimes (like in UL’s patent), it helps to use some high shear for a couple of minutes but that’s about it.
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Thanks
What if we don’t mix it at all after homogenization until temperature is down to 50°c?
Is it necessary to slow mix?
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I did that once, and the product was thicker but rough. Also, not mixing makes the cooling process longer.
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Thanks a lot
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