Viscosity Tips for Cosmetic Products
On another discussion group someone asked how to determine the correct viscosity range and spindle for your formulas. Specifically, they wanted to know what parameters go into making a viscosity range and picking a spindle.
First, see this post for a quick primer on fluid viscosity see this post we did and then look at what the viscometer manufacturer Brookfield has to say about what is viscosity.
Viscosity factors to consider
The key things to consider when picking a spindle and speed.
1. Target viscosity of the product. This is more dependent on the marketing of the product than the formulating. Body wash/shampoo have viscosity ranges from 5000 - 20,000 cps. But lotions, gels, and other products vary. If you haven’t set a target viscosity find a competitive product that looks like what you want.
2. Middle of the range. Get spindle/speed combination that puts target viscosity at middle of the range. A Brookfield viscometer has a range from 0 to 100 (at least the old analog ones did) which was then multiplied by a factor depending on spindle & speed. Ideally, you want to use a spindle and speed that gives a reading of 50.
3. Use “drilling” viscometer for non-Newtonian fluids. Since some products get thinner as you apply a force (e.g. creams & gels) you need a movable viscometer so the reading is more reflective of the static product. Brookfield calls this type of viscometer a Heliopath. Typically, you use T-bar spindles for these products.
Do you have any other tips for taking viscosity? Leave a comment below.
