Give Food Coloring Time To Fully Dye Your Royal Icing
Royal icing is not buttercream icing. While both are used for decorating, buttercream stays soft, while royal icing hardens to a candy-like texture. If you want the best decorating results with royal icing, it is important to get the color right. To accomplish this, you need to do something simple that you might never have thought was important.
For the color to develop to a full, rich shade, let it set after mixing. A 30 to 40-minute wait is the minimum. However, for the most vibrant hues, let it sit for 2 to 4 hours. This is especially true for darker colors.
The problem with giving the color of your royal icing time to fully dye is that it can harden or begin to crust over while you're waiting. To prevent that from happening, store the icing in an airtight container with a slightly damp paper towel on top. This will provide you with the time needed for the icing to obtain the deepest color without giving it a chance to harden.
Other tips for getting the best royal icing colors
Besides giving the dye time to set, there are a few other simple things you can do to get the best color from your royal icing. Begin with a streak-free mix. When blending colors, make sure you stir the food coloring into the icing until it reaches an even shade throughout. There should be no darker or lighter streaks or swirls marring your icing.
Another important tip to remember is that it is easier to go darker than lighter. In other words, start with a slight tint. If it is not dark enough, add more dye. If you do go too dark, all is not lost. You can add white icing to the mix to diminish the intensity, but this might give you more icing than you need.
Finally, know when to stop. When royal icing dries, the color gets a little darker. Admittedly, it may take some trial and error for you to get this right, but the general idea is to mix your colors a shade or two lighter.