Color Mixing & Color Theory

Why color fades, shifts, or turns out wrong

There are three things that generally cause food color to fade or shift: pH, UV light sensitivity, and heat. Most "why did my color do this" questions trace back to one of those three, plus a fourth factor that isn't about the color at all: how much pigment actually went in versus what the recipe needed.

Red icing that turns out pink is usually underpigmentation, the icing itself is white and dilutes every drop added, so a weak or thin color runs out of pigment before reaching true red. It can also just need time, food coloring often takes time to fully develop, so a pink that looks underwhelming right after mixing can deepen into red as the pigment settles. Stopping one shade early and waiting beats piling on more color. In rarer cases the color in the bottle has lost potency from age or heat, and even the right amount won't reach true red if that's happened.

Black icing that dries green is a blend problem: black food coloring is typically blue, red, and yellow together, not one pigment. Red is more sensitive to light and pH than the other two, so it fades fastest, and as it fades the remaining blue and yellow become more prominent, which reads as a green shift. Starting from the darkest base you can reduces how much fading the blend has to do. Icing colored with highly concentrated synthetic dyes, black included, also tends to stain teeth temporarily, the same way it can stain hands, it fades on its own and brushing helps it along.

Bitterness is a separate issue and usually isn't the food coloring itself, it's overpigmentation. Pushing far past the amount actually needed to reach a deep shade brings along whatever's concentrated alongside the pigment, often acidic preservatives or the base ingredient, and that reads as bitter. The fix is reaching the shade with less product: a concentrated color gets there in a fraction of the volume a weak one would need.

Mixing the shades everyone struggles with

Teal is made from blue and yellow, at a ratio of about one part blue to three parts yellow. Mix in gradually and let the color sit for a few minutes before judging the shade, since gel keeps deepening after you stop mixing.

Grey comes from black used in a small dose, mixed into white icing a little at a time until you reach the shade you want. From there, adjust the temperature: a touch of blue for a cooler grey, a little brown for a warmer one. Use a concentrated, true black rather than a weak one, a weak black tends to drift green or purple as it dilutes instead of staying a clean grey.

Lilac is a soft purple. Take a purple gel color, or lavender, and add small drops at a time into white icing until you reach the tone you want, mixing fully between each addition since pale shades show every extra drop. Stop a shade lighter than your target, purple deepens as icing rests, and purples are among the quickest colors to fade in light, so keep the finished icing covered and out of direct sun.

Brown is the natural midtone you get from combining all three primary colors, yellow, red, and blue, though red is typically the dominant of the three for a true brown look. Go slowly and adjust in small amounts, too much blue drifts the batch toward grey-green, too much red toward brick. For icing, cocoa powder is an easy shortcut that colors and flavors at once, but a premade brown gel is the most consistent route since balancing three colors by eye is hard to repeat batch to batch.

Peach comes from a warm yellow base with a small amount of red added, rather than reaching for orange or a premixed pink, which can push the shade toward coral or salmon faster than expected. Add the red a drop at a time into the yellow-tinted base and mix fully before adding more. If the result reads too warm, a touch of white pulls it back toward pastel; too cool or grey, a bit more yellow warms it back up.

Getting it to hold: batter, fondant, and true dark colors

Cake batter color reads paler after baking than it looked in the bowl for two reasons: heat diminishes pigment intensity and can push a color back toward a more neutral, baseline tone, and baked crumb always reads lighter than wet batter regardless of heat. Color the batter a shade or two deeper than your target to account for both, and judge the final color only after the cake has cooled.

Fondant fades for two separate reasons, acidity and light. Avoid adding lemon extract or other acidic flavorings directly into fondant, the acidity can shift the color, and keep the finished piece out of direct sunlight, stored covered rather than near a window. Color a shade or two deeper than your target here too, since fondant fades in light over time and can dry slightly lighter than it looked when mixed.

For genuinely dark colors in white frosting, the fix is concentration and patience together: use enough concentrated color, thin liquid runs out of pigment before the icing gets anywhere near dark, and stop mixing one to two shades lighter than your actual target. Then let it rest, color fully develops over time, anywhere from fifteen minutes up to two hours depending on the shade and how much color went in. Icing that looks underwhelming right after mixing often reaches the target shade on its own without adding more, piling on additional color instead of waiting is what leads to bitter-tasting icing.

A few things worth knowing before you start

• ✦ Color keeps developing after you stop mixing, fifteen minutes to two hours depending on the shade. Stop a shade lighter than your target and wait before adding more.
• ✦ A weak or diluted color runs out of pigment before reaching a deep shade, which is exactly what pushes red toward pink and grey toward green. Concentration solves more color problems than technique does.
• ✦ With thirty years of experience, The Sugar Art is recognized as the industry standard in food coloring, professional-grade lines are typically two to three times stronger than grocery-store or hobby brands.

Frequently asked questions