- 7 days ago
- 4 min read
When formulating cosmetics at home, one of the most important concepts to understand and implement is Good Manufacturing Practices (GMP). This is what separates a product that is simply “made” from one that is safe, stable, and professionally executed.
GMP is not just for large-scale laboratories—it applies to every single batch you create,
regardless of size. If you are working with water-based products, actives, or even anhydrous
systems that may come into contact with moisture during use, GMP becomes essential.
Why GMP Matters More Than You Think
Improper GMP doesn’t just create messy workspaces—it directly impacts your formulation.
It can introduce microbial contamination
It can overwork your preservation system
It can lead to product failure or reduced shelf life
One of the biggest misconceptions in DIY formulation is assuming that contamination is always visible.
It is not.
A product can look, smell, and feel completely normal while still containing harmful levels of
bacteria, yeast, or mold. By the time contamination becomes visible, the product has already
failed.
This is why GMP is focused on prevention, not detection.
Start with a Clean, Controlled Environment
Your workspace is your first line of defense.
Even in a home lab, you should:
Work on clean, disinfected surfaces
Remove clutter before starting
Keep pets and food out of the area
Tie your hair back and practice proper hand hygiene
Every surface and tool that comes into contact with your product should be treated as a
potential contamination point.
Why 70% Isopropyl Alcohol is More Effective Than 99%
It’s common to assume that 99% isopropyl alcohol is stronger and therefore better, but for
Sanitization, 70% is the gold standard.
Here’s why:
The added 30% water slows evaporation, allowing for longer contact time
This improves the alcohol’s ability to penetrate and destroy microbial cell walls
It effectively denatures proteins and disrupts cellular function
In contrast:
99% isopropyl alcohol evaporates too quickly
It may not remain on the surface long enough to properly disinfect
It can dehydrate microorganisms without fully destroying them
How to Use It Properly
70% isopropyl alcohol should be used to:
Sanitize work surfaces
Wipe down equipment after washing
Clean tools, scales, and mixing vessels
Sanitize packaging (when appropriate)
Always allow it to air dry completely—this is part of the sanitization process.
Proper Cleaning: The Step You Cannot Skip
Sanitizing is not effective if the surface is not properly cleaned first.
Step 1: Wash with Hot, Soapy Water
This removes:
Oils and butters
Residual raw materials
Dust and debris
Microbial buildup (including biofilms)
Hot water helps melt lipids and improves the effectiveness of your detergent. Without this step, alcohol cannot properly contact the surface underneath the residue.
Step 2: Rinse with Distilled Water
This is a critical but often overlooked step.
Tap water can contain:
Minerals (calcium, magnesium)
Trace contaminants
Microorganisms
If you rinse with tap water and let it dry, you can reintroduce impurities back onto your
equipment.
Using distilled water ensures a clean, residue-free surface before sanitization.
The Full Cleaning & Sanitizing Process
Wash with hot, soapy water
Rinse thoroughly
Final rinse with distilled water
Allow to dry (air dry or lint-free cloth)
Sanitize with 70% isopropyl alcohol
Allow to air dry completely
This ensures both physical and microbial cleanliness.
Packaging: One of the Most Overlooked GMP Failures
Packaging can make or break your product—even if your formula is perfect.
Ideally, your packaging should arrive sanitized from your supplier and ready for
immediate filling. This is the standard you should expect when sourcing cosmetic packaging.
If your packaging:
Arrives dusty
Has visible debris
Does not appear clean or protected
...it may be worth re-evaluating your supplier. Contact them immediately to initiate a return.
When You Must Sanitize Packaging at Home
If you have no other option, be extremely cautious.
Only sanitize open-neck jars
These are easier to access and properly clean
Avoid attempting to sanitize:
Pumps
Sprayers
Airless systems
Bottles with narrow openings
These types of packaging have crevices and internal components that are difficult to clean
and dry properly. Incorrect sanitization can actually introduce more microbes, not remove
them.
Preservation Systems Are Not a Safety Net for Poor GMP
Preservatives are designed to control microbial growth, not compensate for
contamination-heavy manufacturing conditions.
If your GMP is poor:
You introduce a higher microbial load into the product
Your preservative system becomes overworked
This can lead to:
○ Shortened shelf life
○ Reduced preservative effectiveness
○ Complete product failure
Even a well-formulated, broad-spectrum preservation system has limits.
A Personal Note from Kennece, Your Cosmetic Chemist
When I first started formulating, I was focused on ingredients—what oil to use, what butter felt the best, what actives would give the best results. Over time, and through both education and experience, I realized something very important:
The success of a formulation is just as dependent on how it’s made as what goes into it.
I’ve seen beautiful formulas fail—not because the formulation was wrong, but because the
manufacturing process wasn’t controlled.
GMP is something I take very seriously in my own lab and something I continuously emphasize in my classes, ebooks, and formulations. Not to overwhelm you—but to protect you, your products, and anyone using them.
You don’t need a commercial lab to do this right. You just need to be intentional, consistent,
and disciplined in your process.
Because at the end of the day, we’re not just making products—we’re creating something
people trust to put on their skin. And that trust starts long before the product is finished.
