Oh...one thing I noticed was that when I made fondant rectangles to simulate the box top on my Tiffany cake, I used the same color and could not get them to match the buttercream exactly. I had to add a touch of yellow to the fondant to get it close. I kept wondering why until my Homer 'DOH' moment when I remembered that my buttercream was made with real butter (yellow base).
A closed mouth gathers no feet.
A closed mouth gathers no feet.