Thanks Dan
that worked great.
i have another effect that im trying to create that i would be keen to get your advice on.
basically what i have is a background comp similar to the example at the start of this topic (round circles, but i have 60 of them) i want to start with all circles black (off) and then randomly select them and turn them “on” (to a random colour) one at a time, they then stay at their random colour until all 60 have turned on, then they do the reverse (turn off to black one at a time)
any ideas how i can achieve this with an expression?, or at least an idea of where i should start?