I have a cake-making book that is, first of all, of European origin so it is hard enough to interpret some of the terms used in the recipes. Secondly, it tells me how to marble the fondant, (called "Sugarpaste Icing"), but the instructions are brief and vague.
I do suggest that for a cake you use colors that are somewhat similar in intensity. A light tan and a dark tan, light blue and a darker blue, etc.
The subtle color changes are very pleasing to look at.
Place them side by side on the counter.
If you want 3 or 4 colors, you add them the same way at this point.
Now twist colors together like a breadstick.
I usually pinch the ends together so that it is easier for me to handle.
Now you fold the batch in half so that the bunch of fondant is 6 to 8 inches long.
Lightly cornstarch the counter and place the roll on the cornstarch.
Start to gently roll the batch out. You will be seeing the marbling effect as you are rolling. If you want more effect, twist and fold until you get the desired effect.
That is all there is to marbling.
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Buttercream Icing 101
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