I'm making a tiara from Royal Icing - to be place on a cake frosted with Buttercream icing. Will the Royal Icing absorb any moisture from the BC icing? The customer wants as little fondant as possible, so covering the cake in fondant isn't an option.

Thanks in advance for your suggestions.

If you have piped the crown thick enough there should not be a problem....... but to help why not place the crown on a ring or circle of fondant just big enough to accommendate it.

I put royal icing letters, which would be a lot thinner than a crown, on BC all the time. They stay hard for quite a while (hours). I would think a crown, which would be thicker, would hold up for much longer.

Thanks!

I'm delivering the cake Friday afternoon - the party is Saturday. I think I'll make a small fondant ring for it to sit on just in case. I'm hoping that the buttercream will be crusted enough so it won't be an issue, but you never know . ..

It's only going to be an issue if you are in a high-humidity area. The ONLY time I've had my RI decorations melt was at my dd's first birthday party - August in New England with 75%+ humidity and no air conditioning. If you deliver on Friday for a Saturday party, you shouldn't have any issues.