Hair developer doesn't exactly "go bad" in the traditional sense of spoiling, but its effectiveness diminishes over time. This is because the hydrogen peroxide within the developer can break down, reducing its volume strength, or it can become more concentrated through water loss.
Factors Affecting Developer Lifespan:
- Storage: Proper storage is crucial.
- Frequency of use: The more you open the bottle, the more the hydrogen peroxide degrades.
- Original quality: Higher quality developers may have stabilizers that extend their shelf life.
Signs of Deterioration:
- Weakened strength: If the developer's volume (e.g., 10, 20, 30, 40) is reduced, it won't lift hair color as effectively.
- Changes in consistency: It might become thicker or thinner than usual.
- Discoloration: While not always indicative of a problem, significant color changes could suggest degradation.
Estimating Developer Lifespan:
While a definitive "expiration date" isn't always printed, consider these guidelines:
- Unopened: An unopened bottle of developer can often last for 2-3 years if stored properly (cool, dark place). However, checking for any visible signs of degradation is still important before using.
- Opened: Once opened, developer typically remains effective for 6 months to 1 year. This depends heavily on how well it's stored and how frequently it's exposed to air.
How to Store Hair Developer:
- Keep the cap tightly sealed: This prevents air exposure, which accelerates degradation.
- Store in a cool, dark place: Heat and light can break down the hydrogen peroxide.
- Avoid extreme temperature fluctuations: Don't store it in a bathroom where temperatures and humidity change frequently.
- Keep away from children and pets: Hair developer contains chemicals that can be harmful if ingested or come into contact with skin or eyes.
Important Note:
Always perform a strand test before applying developer that's been opened for a while. This will help you assess its effectiveness and avoid unexpected results. If your developer appears or smells different from when you bought it, it's best to discard it and buy a new bottle. Using ineffective developer could lead to unsatisfactory or uneven hair color.
