Have a few straggly greys and not booked into hairdresser until November so thought I could try this until then. Is the patch test essential? have had hair dyed every few months with no reactions at the hairdressers.
AFAIK you are supposed to do a patch test each time, even with the same product in case you have developed an an allergy since the last time - occasionally a reaction can be caused by repeated exposure.
Used to get my hair coloured at the Vidal Sasson academy (by students) & they were very strict about patch tests if you hadn't had your hair dyed within the previous six months - but I've never had another hairdresser suggest it.
(Sorry didn't mean to hijack your thread with a horror story - it really is very, very rare but so sad for the young girl above who'd dyed her hair loads of times with no problem by the sounds of things & was just terribly unlucky).