Yes, hair developer, which is essentially hydrogen peroxide, doesn't go bad in the sense that it spoils like food. However, it does deteriorate over time.
Understanding Hair Developer Deterioration
Hair developer, primarily hydrogen peroxide, undergoes a chemical breakdown. This means the hydrogen peroxide gradually decomposes into water and oxygen. This process weakens the developer's potency. A 10-volume developer, for example, might decrease to a 9-volume or lower strength. Conversely, it can also become more concentrated, going from a 20-volume to a 22-volume or higher, through dehydration—a loss of water content.
Signs of Deterioration:
- Reduced effectiveness: The most significant sign is a noticeable decrease in its lightening or lifting power during hair coloring.
- Changes in consistency: Although less common, some changes in texture (like thickening) might indicate deterioration.
- Expired date: Always check the expiration date printed on the product packaging.
How to Prevent Deterioration:
- Proper storage: Store hair developer in a cool, dark, and dry place. Avoid extreme temperatures and direct sunlight.
- Airtight container: Keep the bottle tightly sealed after each use to minimize exposure to air.
- Use before expiration: Always use the developer before its expiration date for optimal performance.
Therefore, while not technically "bad" in the traditional sense, hair developer loses its effectiveness over time due to chemical breakdown and dehydration. Using an expired or deteriorated developer may lead to unpredictable and unsatisfactory results during hair coloring.
