Hi,
Thank you for your question! 🥰
The product can be used to color already lightened hair, as it contains a relatively mild oxidant. However, we do not recommend using the product if your hair is clearly damaged ❣️
You can see from the product images which darkness level can be used for which shades.
Please note, however, that the final result of the color also depends on which hair color it is applied to 😊
If the hair is pure blonde, the final result is generally also brighter/closer to the product image result than if, for example, the lightened hair is yellowish/orange.
Generally, the greenish tone you mentioned appears if a slightly darker, cooler shade is added to light hair. This is because the hair lacks warm pigment, and for this reason, the shade tends to turn green. However, I believe that this problem will not occur with the lightest shade variations 🤭
Hope this helps 🤍 Have a wonderful day!