(Applied on Chestnut - color remains the same and covers grey hair)
4N can be used on the following colours to achieve a dark tone colour:
5N - 6N - 7N - 4D - 5D - 7D - 8D - 4M - 5M - 7M - 4R - 5R - 7R - 8R - 4C - 7C
4N - Chestnut with 5% grey hair
If grey hair is all over the head, you can use 4R, this will create highlights on the grey hair and Copper Chestnut on the rest of the hair. On more than 5% you must use this formula.
4N - Chestnut with 10% - 20% grey hair
Mix 25ml of 4N, 35ml of 4R, 60 ml of glycol to get a Copper Chestnut.
4N - Chestnut with 30% - 50% grey hair
Mix 30ml of 4N, 30ml of 4R, 60ml of glycol to get a Copper Chestnut.
4N - Chestnut with 60% - 100% grey hair Mix 45ml of 4N, 15ml of 4R, 6Oml of glycol to get a Copper Chestnut.
This formula will apply for 4M Mahogany Chestnut, 4D Golden Chestnut and 4C Ash Chestnut.