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Is it normal for W/O cream to double its viscosity few hours after production?
Hi all,
I have noticed my W/O cream to have its viscosity doubled (from 45.000 mPas to 90.000mPas) within 4 hours after its production at room temperature. Is this normal and how can it be explained? Also, the 25C stability sample retains this viscosity value for weeks, while the 45C oven stability sample looses it. Any thoughts?
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4 Replies
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It is normal. Really depending on your waxes and lipids.
Sometimes the full viscosity is reached a few days after manufacture.
And yes, the higher temperature the more “liquid” your product will be. 45°C is considered high temperature for stability testing and will not likely to happen in real life.
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It’s actually quite common, especially with certain fatty alcohols. At a company I worked with we would recheck these batches at 24 and 48 hours post-manufacturing while they were still in QC hold.
As mentioned previously, the viscosity will not be seen at 45C. You would use RT samples.
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Thank you both for your replies.
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I can add here @ntina that your 45C ACC sample will generally fail if this is an invert (w/o) emulsion. Virtually all invert emulsions are thermodynamically unstable. We classify these as meta-stable. I have 10-year-old w/o samples that still basically look fine but have the same small amount of syneresis they had at 24 months at RT. The ACC sample was disjoined at 30 days as I recall. The world of invert emulsions (w/Si are same) is a topsy-turvy one.
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