Just my 2 cents:
I have BLACK eyebrows and NOTHING works to color them, not the colored mascara, not the Ben Nye hair color, nothing.
I have faked it in the past with a colored pencil, but tomorrow is AX and my new wig is silver. So I figured I'd give this a try...
It worked really well! I wore the glue/ paint for the last hour and just washed it off. Everything worked fine and it washed off easily with a tiny bit of scrubbing and some soap.
So I'll be trying it tomorrow and hoping it holds up for the con.
Thanks for the tutorial =)