Do edible images have to be put on a certain kind of icing? I heard that sometimes the colours will run/leak if the icing isn't the right kind, if buttercream is not made with real butter. Is this true? I am getting a bakery to print an edible image for me and I want to make sure it will work on my cake.

It is fine if your BC is made of shortening I do it all the time. It doesn't work on whipped cream style icings as well as they are too wet. The wetness will make your image bleed and distort.

I just put them on bc made with both butter and shortening and it worked great.

I've also put them on cookies with a glaze and it worked fine.

I didn't know there was a difference with the icing and the edible image. I told someone I could make them a cake this weekend with whipped icing and an edible image. Do you think if I keep the cake in the fridge and let the icing harden as much as it will being cold then put the image on right before I deliver it that it will be ok? Has anyone ever done that before? I've used them on buttercream and on cookies with a pourable buttercream and never had a problem so I didn't even think about it.