Here's an example of oil bleeding from buttercream into fabric ribbon. All the ribbon on this cake had been backed with wax paper, which had been cut to size and attached with double-sided tape. Unfortunately, the second-from-the-bottom tier had bleeding nonetheless, because the ribbon made contact with the tier below it. This caused the oil to literally bleed upward from below, rather than from behind where it was actually attached to the cake. Luckily, I was able to fix the problem before the wedding, but I was careful not to allow my ribbons to touch the tier below. Just a head's up!!