You have mixed henna in too cold yoghurt, as when temparature is fridge cold and you mix with henna, the warmth seperates some water from the yoghurt and this has been the reason why you experience yoghurt drips.
Well I have a habit of taking yoghurt and placing in a bowl and letting it sit few hours before adding henna. This tends to make yoghurt more sour. You should take the required yoghurt and allow it to sit few hours, then you will see a liquidy watery seperation on the yoghurt top. Pour this out then add henna. Goodbye to drips enjoy.
Quelle:
H4H