Lab Skills: How to use Dip Slides for Preliminary Microbiological Testing

Cosmetic products that contain water are a perfect breeding ground for microorganisms which is why adequately preserving cosmetic products is so important. The only way to know for sure that they are adequately preserved is through product testing.

Dip slides are a useful and inexpensive way to carry out preliminary microbiological testing. They will show you how many microorganisms are currently present in your product, giving you some information on how well your preservative is working. What dip slides can’t show you is how well a product would resist microbial growth if we introduced more contaminants into it, for example during consumer use. This can only be determined by a Preservative Efficacy Test (PET) which is strongly recommended (and in some countries required) before a product is placed on the market.

Dip slides are a useful addition to a home lab. The advantages of dips slides include:

• Inexpensive.
• Tests can be conducted at home.
• Easy to interpret results.
• Tests can be carried out quickly.
• Useful if you are making products for your own use and will not send products for PET.
• Useful for preliminary testing of a product prior to PET, therefore can save you money on failed PET.
• Can be used to check the quality of raw materials and finished products.

In this class, we will cover:

• Introduction to microbiology.
• What are dip slides and how do they work?
• Comparison between dip slide testing at home and professional microbiological testing: advantages and disadvantages of each.
• Choosing dip slides.
• Equipment needed.
• How to use dip slides to test liquid and semi-solid products.
• How to get accurate and useful results.
• Reading and interpreting the results.
• Calculating CFU (colony forming units).

This class will help you develop a new and very useful lab skill and you’ll receive a beautiful PDF textbook to download.

Not a member of the Club? Join now and use your first month's credits to access the Lab Skills: How to Use Dip Slides for Preliminary Microbiological Testing class, plus another 25-credit class of your choice.

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