Thanks Hersute for the help. You are really clued in with the colouring. Do you colour your own hair too? My usual colour is actually one of the Indola range as it matches what I want better than any of the Koleston browns. There are no letters for these colours, just numbers so it;s hard to know what's best. I did a test with the ash Koleston today on some paper and it came out green. That makes sense as green is the opposite of red so it woult neutralise red tones, but my pieces have more gold/brass so I think a blue would be better. I'd like to use an Indola ash/blue of some kind. Do you think there's anything in this list that would be the one?

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