In this blog post, we’ll cover the essentials of color mixing with acrylics, including understanding the color wheel, the importance of undertones and color bias, using a split primary palette, avoiding muddy colors, and blending techniques that will help you create vibrant and harmonious paintings. Plus, I’ll share some personal insights from my own journey with color mixing to help you get confident and creative with your palette.
Introduction to Color Mixing with Acrylics
If you’ve ever mixed acrylic paints and wondered why your colors don’t turn out as bright or clear as you imagined, you’re not alone. Early in my painting journey, I often felt frustrated when mixing what I thought would be a beautiful purple but ended up with a muddy brownish mauve instead. Understanding how paints behave and learning the nuances of color mixing transformed not only my results but also my entire creative process.
Understanding Hue, Value, and Chroma: The Building Blocks of Color Mixing
Before we get into undertones and color bias, it’s important to understand the three key dimensions of color that affect every mix you make: hue, value, and chroma.
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Hue is what most people think of as “color” - red, blue, yellow, and all the colors in between. It’s the pure color on the spectrum.
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Value refers to the lightness or darkness of a color. Adding white lightens a color (a tint), adding black darkens it (a shade), and this affects how colors interact in a painting.
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Chroma describes the intensity or purity of a color - how bright or dull it appears. Colors with high chroma are vivid and saturated; low chroma colors look muted or toned down.
When you understand how hue, value, and chroma work together, you can mix acrylic colors more intentionally. For example, I often noticed in my early painting days that a color would look “off” because its value was too dark or the chroma was desaturated or muddy - not because the hue was wrong. Recognizing these three dimensions helped me troubleshoot and get the exact look I wanted.
Whenever you adjust one of the dimensions, the others will automatically be shifted. For example, when you add blue to yellow to make green, you're adjusting both the hue (the color) and the value (green is darker than yellow, because blue has an inherently darker value). If you used a blue with a complementary undertone such as a red, you may dull the chroma by making it muddier and less saturated.
This foundation makes it easier to grasp undertones and color bias, which add another layer of complexity and richness to your palette.
Understanding the Color Wheel and Primary Colors
At the heart of color mixing lies the color wheel. The three primary colors - red, yellow, and blue - are the building blocks from which all other colors are mixed. But knowing just “red” or “blue” isn’t enough.
Each primary can lean warm or cool, which changes how they mix. For instance, a warm red like cadmium red medium leans orange due to its yellow undertone, whereas quinacridone magenta leans cooler, leaning purple with its blue undertone. This is called split primaries, and I'll discuss this more later in the blog post.
What Are Undertones and Why They Matter
Undertones are the subtle secondary hues hiding within a paint color, and they dramatically affect your mixes. When I first learned about undertones, it was a game-changer. I realized that mixing a red with a yellow undertone with a blue might create a dull purple, while mixing a red with a blue undertone with that same blue results in a vivid, jewel-like purple.
Knowing the undertones helps you predict how colors will behave when combined, preventing hours of trial and error and allowing you to choose your paints with intention.
All colors have an inherent undertone. Magentas lean cool with blue undertones, cadmium colors lean warm with red/yellow undertones, and phthalos usually lean cool with green undertones. Knowing this in advance will help you when you go to buy your paints from the art store.
How to Create Vibrant Colors: Warm vs Cool Colors
Warm colors include reds, oranges, and yellows, while cool colors are blues, greens, and purples.
But it’s more layered than that: colors have biases depending on their undertones. For example, ultramarine blue is technically a cool color since it's a blue, but it leans warm because it has a red undertone (red is a warm color). Phthalo blue (green shade) is cool color with a cool bias because of its yellow/green undertone.
Recognizing these biases lets you mix a full spectrum of rich, vibrant colors. For example, pairing a warm red with a cool blue yields more saturated secondary colors than mixing two colors with conflicting biases, which create muddy colors.
Using a Split Primary Palette for Better Mixing
One of the most useful tools in my color mixing toolkit is the split primary palette. This means having both a warm and cool version of each primary color on your palette—for example, cadmium red medium (warm red) and quinacridone magenta (cool red).
This approach gives you the flexibility to mix an incredible range of vibrant colors, from warm oranges to cool purples, all with greater control and clarity.
Earlier, I showed you the split primary palette diagram. If you want to mix vibrant colors, mix colors that are facing each other on the wheel. For example, for a vibrant orange, mix a warm red with a warm yellow. For a vibrant green, mix a cool yellow with a cool blue. For a vibrant purple, mix the cool red with a warm blue.
Complementary Mixing: How Opposites Create Harmony and Depth
Above: a complementary mixing chart from my Color Mixing with Acrylic course, showing what happens when red is mixed into green, yellow is mixed into purple, and blue is mixed into orange.
Complementary colors are pairs of colors directly opposite each other on the acrylic color wheel. They create beautiful contrasts and can be used to tone down colors for natural, harmonious effects.
When placed side by side, complementary colors enhance each other’s vibrancy. For example, bright orange pops against deep blue. When mixed, they neutralize each other, creating muted earth tones like olives, browns, and grays—perfect for realistic shadows and backgrounds.
Complementary colors can also be referred to when trying to avoid mixing muddy colors.
How to Avoid Muddy Colors When Mixing
A common frustration is muddy mixes. This happens when colors with opposing undertones or complementary colors mix too evenly, canceling each other out.
Let's just say you mix a warm red with a cool blue: you'll get mud, since the yellow undertone in the red will mix with the blue to create green, which will dull the purple you were after.
Or mix a warm blue with a warm yellow: you'll get a muddy green, since both colors will have a reddish undertone, which is complementary to green.
When I first struggled with muddy purples, it was because I mixed cadmium red medium (yellow undertone) with ultramarine blue, introducing yellow into the mix, which dulls purple. The key is understanding undertones and pairing colors that lean toward each other, so your mixes stay bright and clear.
Tips for Mixing Secondary Colors
Mixing secondary colors - green, orange, and purple - becomes much more reliable and vibrant when you use a split primary palette. This means having both warm and cool versions of your primaries, which helps you avoid muddy or dull mixes.
For example, pairing phthalo blue (a cool blue with a green undertone) with cadmium yellow medium (a warm yellow) results in lively, bright greens that retain clarity and vibrancy. On the other hand, mixing ultramarine blue (a warm blue with a red undertone) with quinacridone magenta (a cool red) produces rich, deep purples with a jewel-like quality.
Why does this work? Warm and cool primaries have different undertones that either enhance or clash when mixed. Using a warm yellow with a cool blue prevents clashing undertones and keeps your secondary colors pure and intense. Conversely, mixing primaries with similar undertones can cause colors to lean muddy or gray because complementary undertones neutralize each other.
Common Mistakes in Acrylic Color Mixing
One mistake I made early on was assuming all reds or blues behave the same. Learning about color bias and undertones was essential to fixing that.
For a full YouTube video breakdown of this, you can watch my tutorial below, or checkout this blog post: Top 5 Acrylic Color Mixing Mistakes (and How to Fix Them)
Frequently Asked Questions
What causes muddy colors when mixing acrylic paints?
Muddy colors usually result from mixing paints with opposing undertones or complementary colors in equal amounts, which neutralize each other and dull the color.
How do undertones affect acrylic paint mixing?
Undertones are subtle hues beneath the dominant color that influence how paints mix. Matching undertones lead to more vibrant colors; opposing undertones can dull mixes.
What is a split primary palette and why use it?
A split primary palette includes both warm and cool versions of each primary color. It gives you more flexibility and vibrancy in your mixes.
How do I blend acrylic paints smoothly?
Build up layers gradually, work while the paint is wet but not overly wet, and let transparent layers dry before adding more paint for smooth gradients.
Can I mix pastel colors with acrylic paints?
Yes, adding titanium white to your mixed colors creates tints, or pastels, with softer hues.
What are analogous colors and how do I use them?
Analogous colors sit next to each other on the color wheel and blend harmoniously, creating smooth transitions in your paintings.
Ready to take your color mixing even further?
If you found this blog helpful, you’ll love my Color Mixing with Acrylic course. It’s designed to help you build confidence with your palette and finally understand how to mix any color you need - with clarity and intention.
You can also sign up for my FREE 36 page Introduction to Acrylic Painting eBook and join over 11,000 artists on my email list for free weekly painting tips and tricks.
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