Inconsistent of Production Viscosity

Dear all, 
Wish everybody is safe in this tough time. 
I have some questions regarding the control of product viscosity during production. The background of the story is I have some formulations with consistent viscosity during lab batch. However, the viscosity is always inconsistent when it goes to production. The viscosity is fluctuate largely. Some batch are far too high while some are way too low from the lab batch. The viscosity of production batch is also drop over time, and some are dramatically fall. It happens mainly in w/o foundation and anhydrous lip cream production. The production process I'm practicing is I put 70% of pigment in oil phase before emulsification process, then carry out the colour adjustment using pigment dispersion after the emulsion formed.  

So my questions are: 
1. Why are there such a large difference across the production batch? 
2. Is the blending method wrong and how to correct it? 
3. Is blending time a factor to consider as well? 
4. How can we prevent the viscosity fall over time?  [The formula is confirmed stable with 6 months standard stability test, including in extreme condition]
5. What is the correct viscosity range for a foundation with various shade? for example, would a viscosity range off 100 000 - 400 000cps consider too big?
6. Are they any corrective action if the viscosity is under or over the desired viscosity? 

Hope somebody can guide me through this... I really have hard time with this...

Thank you very much in advance. 

Stay safe~
Newbie of formulation

Comments

  • PharmaPharma Member, Pharmacist
    Looks as if you have difficulties scaling production up.
    What's the size of your lab batch and the production patches?
    Do you use a different type of mixer/homogeniser?
  • PeiHoongPeiHoong Member
    @Pharma yes, I'm having difficulties to scale up my product. Lab batch varies from 150g to 1kg. Production from 25kg to 100kg.  In lab batch I use only one type of homogenizer while production  mixer varies according to batch and available machine.  Thank you
    Newbie of formulation
  • mikethairmikethair Member
    My approach would be first to ensure that I have detailed Batch Manufacturing Records (BMR), including in-process testing results. Second, be consistent with your homogenizer. Produce a minimum size batch using the same homogenizer as your larger batches.

    I use BMR's to identify where the issues are, and then try to correct these. It's slow work.  And important that once the issue is sorted that you remain consistent for subsequent batches.

    I had viscosity problems when scaling up a hair conditioner. The above approach sorted it out.
    Dr. Mike Thair
    Cofounder & Chief Formulator
    Indochine Natural
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