Vitamin C serums contain powerful antioxidants that help make skin visibly younger, brighter, smoother and firmer. However, vitamin C (or ascorbic acid) undergoes a decomposition process when it is exposed to elements such as light, heat, or oxygen. Although it is not possible to prevent this phenomenon, you can extend the shelf life of the serum by choosing an appropriate packaging and keeping it in a cool, dark place.
Steps
Part 1 of 2: Keeping the Serum Fresh
Step 1. Close the cap tightly after each use
Since oxygen breaks down vitamin C, you should make sure you close the cap tightly each time you use the product and try to leave it open as little as possible.
Step 2. Store the Vitamin C Serum in the refrigerator
Ascorbic acid has an extremely short shelf life because it tends to oxidize or decompose when exposed to oxygen. The fridge is perfect for storing it, as the cold helps to delay the oxidation process more effectively than room temperature.
Don't have the possibility to keep it in the fridge? Look for a cool, dark spot in your bedroom or other available room
Step 3. Never store Vitamin C Serum in the bathroom
Since this environment has fluctuations in temperature and humidity, the whey will tend to decompose faster than in other rooms.
- Try keeping a portable mirror next to where you store the serum so you can apply it here.
- If you apply vitamin C serum in the bathroom, don't forget to store it in the right place after use. Try using a trick to remember it. For example, you could hold the bottle in your hand for the duration of the application rather than leaving it on the sink.
Step 4. Transfer the serum into smaller opaque containers to make it last longer
Instead of keeping it in a large container, buy or recycle opaque glass vials. Distribute the product between these bottles.
This method is very effective in preventing half of the serum from being exposed to oxygen, making it last longer
Step 5. Discard the serum once it turns yellow or brown
The oxidation of vitamin C causes discolouration. When the product turns yellow, red or brown, then it has oxidized and is no longer effective.
For most formulations, this usually happens after about 3 months of storage at room temperature or after 5 months of refrigeration, although exact times vary by brand
Part 2 of 2: Choose a Stable Serum
Step 1. Avoid choosing a serum containing water, as it will decompose it sooner
Vitamin C begins to deteriorate as soon as it comes into contact with water. This process can be slowed down by adding preservatives, but the balance must be precise and in any case the formulation will have a shorter shelf life than a water-free serum.
Look for a serum made from ascorbic acid (AA), tetrahexyldecyl ascorbate (THDA), magnesium ascorbyl phosphate (MAP), or sodium ascorbyl phosphate (SAP)
Step 2. Choose a less potent but more stable form of vitamin C
L-ascorbic acid is the type of vitamin C most used in the cosmetics sector. Unfortunately, it is also one of the least stable forms. Other types of vitamin C are less potent, but have a greater stability in terms of durability.
Look for a formulation with ascorbyl glucoside, magnesium ascorbyl phosphate, and tetrahexyldecyl ascorbate
Step 3. Look for a serum sold in an opaque jar or airtight bottle
A product exposed to light and air tends to decompose earlier. If you buy a vitamin C serum that is sold in a clear, airtight bottle or jar, it is likely to lose its effectiveness before you can even use it.
If the only product you can find is sold in a clear glass bottle, pour it into an opaque container as soon as you get home
Step 4. Buy vials of vitamin C serum to avoid waste
To avoid wasting large quantities of product, try to buy small bottles. You can also try to find samples of the product you want to test, so that you don't spend too much on a serum that will go bad before you can finish it.
