Riddle Me Half

If you've just half an idea, then let me know here and click the title.

I sprout, I spread, I'm fair as day,

I thicken black, then fade to gray,

I lose my will and run away.

'This week you're shorter. Is that a clue?'
'It is not, I'm both long and short.'
'Well that's the most useless clue I've ever heard.'
'But at least you aren't clueless.'


Riddle Answer Hair