Semi permanent hair colour help please

[yodelehoho]

I'm finding it too expensive and too much of a faff going to the hairdresser every 6 weeks to get my semi permanent colour.

Are the chemist boxes all much and such the same? I have fine hair with a few gray hairs coming through (I'm 52).

Loreal castings are nice semi permanent colours.

Thanks. My friend (who has very similar hair) feels it spoiled hers. She only used it about 4 times a year but it got very dry and damaged. She says she followed the instructions carefully.

That's the only reason that I'd like to try something other than them.