Do I really need to do a patch test every time?
Yes. Sensitivity can develop at any point, even to a product you have used for years. The 48-hour allergy alert test is the only reliable way to catch it.
Will it cover grey?
Both ranges are designed to. Coverage depends on how much grey you have and how coarse it is - a strand test tells you before you commit.
What do the numbers mean?
The number is depth, 1 being black and 10 the lightest blonde. The letter is tone - N for natural, R for copper, and so on.
Is ammonia free the same as chemical free?
No. These are still permanent dyes and still use developer to work. Ammonia free means gentler on hair and far less harsh to use, not that there is no chemistry involved.