There WILL be a grease stain on the ribbon from the buttercream icing.
There are several things you can do:
1. I have read that you can wet the ribbon. Wet the ribbon, squeeze the liquid out and then place the ribbon on the cake. I have never done it that way. I would be afraid the wet ribbon wouldn’t stick to the cake.
2. Grease the ribbon: take a small amount of shortening and rub it over the ribbon, then place it on the cake.
I have tried this once but find it not necessary.
3. Cut strips of wax paper, the same size of the ribbon. Wrap the wax paper around the cake and then the ribbon around the wax paper. You will need to fasten the ribbon in some way, either double stick tap, or a fancy dress maker’s pin.
4. Take the ribbon and just wrap it around the cake. (this IS how I do this) If you are concerned about it not sticking, just use some thinned buttercream to ‘glue’ the ribbon on the cake. I try to make the ends of the ribbon end on the back side of the cake. I take three icing ‘dots’ and cover the end. This seals the ribbon into place.
As far as the grease stain is concerned, usually, I let it just sit and the ribbon darkens on it’s own. You can also take your finger and lightly brush your finger on the ribbon, pressing it lightly into the buttercream. The heat from your hand will soften the icing a little bit and the grease from the icing should come through the ribbon evenly.
Food for thought…Have you thought about making fondant ribbons? They are not too difficult and would stick to the cake without having the grease come through the ribbon.
These are not the only ways to do this, and not necessarily the correct way to do it. It works for me every time I use it.
I hope this helps,
tokazodo
Cake Hatteras
Psalm 127:1 Unless the LORD builds the house, the builders labor in vain.