Product Stability

Microscope picture of DER JOAN Butter Protection

Stability was done on Butter Protection Body Lotion in the following manner: 12 weeks at 45C, 25C (room temperature), 5C and 3 cycles of freeze/thaw.

The method calls for the formulator to evaluate the product on a weekly basis for the first 4 weeks and once a month after that by evaluating the pH and the viscosity of the product. Microscope pictures can also be taken of the product that to measure the oil droplet size of the oil-in-water emulsion. A particle size of 10 microns is usually considered good. Butter Protection has a particle size of under 10 microns. The smaller the droplet particle size the better the odds of the formula making it through the stability process.

Taking pictures of the edges of the product can give information on how well the oil droplets are dispersed in the water. This will give you an idea of how stable the product is. As the above picture shows the particles go right up to the edge signifying that the product has good distribution throughout the water.

The above method allows for an accelerated way to understand how the product will behave as it sits on the shelf. Further studies can be done on the product in the actual packaging (or close to the final packaging as possible) to know how well it will do in the packaging. This is called "compatibility". At times, you can have formula interaction with the packaging depending on the material the packaging is made out of, or the product could increase in viscosity and no longer able to be pumped or pushed out of the bottle. Successfully completing this final study will allow the formulator or Brand to have full confidence in the product's stability as it sits on the shelves. Once the product hits store shelves or sits in a warehouse the formulator will know that their product will be stable.