I made my first cake this week- and I was pretty happy with it! I finished it Saturday afternoon and put a few sheets of saran wrap over the cake, but they were loose- not tightly wrapped. When I got home from Church Sunday morning, and removed the wrap, all of my black polka dots had bled pink onto the white icing! Ack...

I pulled off all of my dots and re-did them with larger spots. Luckily I had put all of the icing in the refrigerator just in case I needed to make a repair.

Does any other icing bleed? This was a pre-mixed BLACK food coloring that I purchased from a cake supply store.

The good thing was the cake tasted great, and quite a few people asked me where I had bought it. Very satisfying!

Was this fondant or buttercream?
I find that you have to make sure that fondant that is darkly colored is very dry (i.e., use just a tiny smear of liquid to adhere to the cake). If it was buttercream, I'd say to not cover it at all because that increases the chance of condensation.
That being said, it's always a bit of a chance that "mega" colors like red and black will bleed onto a lighter color in my experience. It does get better with practice though.
I'm sorry you had a junky time with this cake but it's awesome that it came out good in the end!

Black food coloring has a TON of different colors in it, and it can bleed if there's too much in it. For black accents I'd use black fondant just to give it less of a chance of bleeding. When I roll black fondant out it turns the counters pink, so it definitely has a lot of red in it.

Having said that, I do make black icing and it does fine and doesn't run. I usually start with a chocolate icing, then add black airbrush color to it. Then you let it sit overnight to give it time to darken. If you start with the chocolate you don't have to use as much food color, and letting it sit will allow it to darken so you don't hve to use as much color.

It might also have had something to do with the plastic wrap. If the icing was covered with plastic the moisture in it will recirculate and it won't dry out on the surface. Letting the surface of the icing dry out will prevent some of the bleeding, but if everything stays moist it will probably have more of a chance to bleed. Maybe I'll do a little experiment with that and see if it makes a difference. Thanks for the blog post idea!