I want to do black scrolls on white buttercream - how do I keep the black from bleeding? Do I need to do the scrolls in royal? Thanks in advance for your thoughts!

I just read a thread on this question but can't find it now. Someone did a little test and found that the scroll didn't bleed when the icing was allowed to crust overnight, but bled if allowed to crust only an hour. If you go to google and type in preventing bleeding cake central a bunch of cake central threads come up. You could play around with the search words to check about royal icing.