When and why do you need to use preservatives?
Cosmetic products need to be be preserved in order to prevent microbial spoilage that would make the product unsafe for consumers.
Preservatives play a very important function in products containing water: they kill microorganisms and water-borne bacteria, and prevent the growth of bacteria, mold and yeast. If a product contains water (including hydrosols, floral water and aloe vera juice, all of which contain water), a preservative is essential to help prevent microbes growing.
Anhydrous (water-free) products generally don’t require preservatives as they are not prone to microbial contamination. This includes products like lip balms and anhydrous whipped body butters. The exception here is an anhydrous product that might come into contact with water (eg a body scrub or a cleansing balm applied with wet fingers). With these types of products you either need to be very careful not to introduce water to the product during use, or you should include a preservative.
Here are 3 broad spectrum natural preservatives for cosmetics:
The preservatives in the list below are all approved for use in certified organic products. They are either derived from natural sources or are nature identical.
REMEMBER: It is your responsibility to check the efficacy of your preservative system. We strongly recommend having a microbiological challenge test carried out by a lab as this is the only way to be completely sure that your preservative system is effective. You can find more information on product testing here: Guide to cosmetic product testing and safety assessments.
1. Preservative Eco
Other trade names include Mikrokill ECT, Geogard ECT and Plantaserv M.
INCI: Benzyl Alcohol (and) Salicylic Acid (and) Glycerin (and) Sorbic Acid
This is a broad spectrum preservative which contains four different components: Benzyl Alcohol, Salicylic Acid, Glycerin and Sorbic Acid. These molecules are all found in nature in plants such as pine resin, rowan berries and willow bark. It is a non-paraben, non-formaldehyde, non-isothiazolone based preservative system.
It’s a liquid that is added to the cooling phase of a cream. It has a slight almond-like smell that is normally not detectable in the finished product. Over time, benzyl alcohol oxidizes to benzaldehyde, which has a strong almond smell. Suitable for use in oil-in-water, water-in-oil and water based formulas, so compatible with a wide range of skin, hair and sun care formulations.
Not permitted in products for children under the age of three years due to the salicylic acid content.
It is supposed to have a wide pH compatibility of pH 3-8, but it’s most effective at pH below 5.5.
2. Geogard 221
INCI: Benzyl Alcohol (and) Dehydroacetic Acid
Dehydroacetic Acid and Benzyl Alcohol are both organic compounds which are accepted for use in natural cosmetics, offering a broad spectrum of stability at a wide range of pH. The organic preservative compound is a non-paraben, non-formaldehyde, non isothiazolone based preservative system.
It is water soluble with an effective pH from pH 2-6; it’s most efficient at pH below 5.5.
Typical recommended use level is 0.2-1%.
3. Euxyl K 712/Potassium sorbate and sodium benzoate
INCI: Sodium Benzoate (and) Potassium Sorbate
It is a liquid cosmetic preservative, which can be used in leave-on as well as in rinse-off products. It was developed for use in cosmetic formulations with a skin-friendly pH value of up to 5.5. It has a broad, balanced spectrum of effect against bacteria, yeasts and molds.
Its activity greatly depends on the pH of the product; the lower the pH, the higher the activity. It is best used at pH below 5.5, ideally around 4.0-4.5.
Usage rates are between 0.5% and 1.5%. It can be added to the heated water phase, but prolonged heating periods (maximum four hours) above 80°C should be avoided.If you cannot easily obtain Euxyl K 712 you may find it easier to buy sodium benzoate and
potassium sorbate individually (they are widely available separately as powders/pellets). As a replacement for 1% Euxyl K 712 you should add 0.2% potassium sorbate and 0.3% sodium benzoate to your formulation. If you choose to add these, they will need to be added to the water phase and heated until dissolved.
You will need to use a broad spectrum preservative, which means it is effective against bacteria, mold and yeast.
It’s important to follow the manufacturer’s instructions regarding the amount of preservative to use; too much or too little could be potentially hazardous.
The only way to know that your preservative is working sufficiently is to have a microbiological challenge test carried out by a lab. This is recommended (and in some countries compulsory) if you are selling your products.
Vitamin E, rosemary extract and grapefruit seed extract are not preservatives.
Source: https://www.schoolofnaturalskincare.com
