Color & Mixing
Transparent, Staining, and Granulating Paints Explained
Learn how transparency, staining power, and granulation affect your watercolors and which pigment properties matter most for beginners.
Pick up any quality watercolor and you will find a small panel of symbols on the tube or pan. Most beginners ignore them entirely. That is a shame, because those symbols tell you three things that change how a color behaves in your painting: how transparent it is, whether it will stain the paper permanently, and whether it will separate into a grainy texture when it dries. Understanding these watercolor paint properties takes about ten minutes and saves a lot of frustration later.
Transparency: How Much Light Gets Through
Watercolor works by letting light pass through the paint, bounce off the white paper underneath, and come back to your eye. The more transparent a pigment is, the more light gets through and the more luminous the result. Opaque or semi-opaque pigments sit on the surface and block some of that light, which produces a chalky or matte effect.
Most manufacturers rate each color on a scale using one of four labels:
- Transparent (T) - Light passes through almost completely. These colors are ideal for glazing layers over each other and for building rich shadows.
- Semi-transparent (ST) - Mostly clear with a slight veil. Works well in both layering and direct painting.
- Semi-opaque (SO) - Begins to block light noticeably. Useful for tinting or softening, less so for clean glazes.
- Opaque (O) - Sits on the paper surface. Can lift or muddy layers beneath when painted over.
In practical terms, transparent pigments like Phthalo Blue (PB15), Quinacridone Rose (PV19), and Viridian (PG18) produce glowing results in washes and layers. Opaque pigments like Cerulean Blue (PB35), Naples Yellow, and most Cadmiums tend to look heavier. Neither group is better overall. You just need to know which one you are using.
A quick test: paint a swatch over a pencil line once the first layer has dried. If you can still read the line clearly, the paint is transparent. If the line disappears, it is opaque.
Staining: What Stays on the Paper
Some pigments bond chemically with the paper fibers. Once dry, they cannot be lifted back out. These are called staining pigments. Others sit loosely on the surface and can be rewetted and blotted away, which gives you far more room to correct mistakes.
This property matters in two main situations. First, when you want to lift out a highlight or soften an edge after the paint has dried. If you painted with a staining pigment, that area is permanent. Second, when you mix colors on the paper and later want to push the balance in a different direction, staining pigments resist any adjustment.
Common staining pigments include Phthalo Blue (PB15), Phthalo Green (PG7), Quinacridone Magenta (PR122), and Prussian Blue (PB27). Common non-staining or low-staining pigments include most Ultramarine Blues (PB29), Raw Sienna (PBr7), Burnt Sienna (PBr7), and Yellow Ochre (PY43).
To test a pigment yourself, paint a swatch on your usual paper, let it dry fully, then scrub the center firmly with a damp stiff brush. Staining pigments leave a clear ghost of color behind. Non-staining pigments lift away cleanly, often down to near-white paper.
If you are working on a painting that requires corrections or glazing on top of existing color, reach for low-staining pigments in the early layers. Save the staining pigments for final glazes or areas where you want permanent depth.
You can pair this knowledge directly with palette planning. The guide on how to build a limited watercolor palette and why it helps covers choosing pigments that work together, and staining power is one of the variables worth tracking when you make those choices.
Granulation: The Texture Effect
Granulating pigments are made from particles that are too large to stay suspended in the water. As a wash dries, those particles collect in the tiny dips of the paper's surface while the water retreats into the fibers. The result is a soft, sandy, or mottled texture that can look like stone, old wood, fog, or aged plaster.
Heavy granulators include French Ultramarine (PB29), Cobalt Blue (PB28), Burnt Umber (PBr7), Raw Umber (PBr7), Viridian (PG18), and most Manganese-based pigments. Light or non-granulating pigments tend to dry flat and smooth.
Granulation is more pronounced on cold-press or rough paper than on hot-press because the surface texture gives the particles more pockets to settle into. If you want maximum granulation, use cold-press paper, a loose wet wash, and let the paint dry undisturbed. Tilting the board slightly increases the effect. If you want less granulation from a naturally granulating pigment, add a drop or two of water to thin the paint further and let it dry flat.
The effect is not always decorative. When you mix a granulating and a non-granulating pigment together, the granulator separates from the smooth pigment as the wash dries. This is called pigment separation and it produces beautiful blooms and textures that are impossible to achieve any other way. French Ultramarine mixed with Burnt Sienna is a classic example: as it dries, the two pigments drift apart, giving you warm browns in some areas and cool blues in others within a single brushstroke.
Reading a Tube Label
Manufacturers print these properties in different places and use slightly different notation, but the information is almost always there. Daniel Smith labels include a row of symbols at the bottom of the tube. Winsor and Newton print transparency and staining information in their product guides and on the tube back. Schmincke uses a numbered system in their swatch books.
What to look for:
| Property | Common label | What it means |
|---|---|---|
| Transparency | T / ST / SO / O | How much light passes through |
| Staining | High / Low / None (or star ratings) | How permanently it bonds to paper |
| Granulation | Yes / No, or G in some systems | Whether particles settle visibly |
| Lightfastness | I / II / III (or ASTM rating) | How resistant the color is to fading |
Lightfastness is worth adding to this list because fading matters if you plan to display or sell your work. ASTM I or II is reliable. ASTM III and below is not suitable for anything you want to keep.
Putting It Together: Choosing Pigments for Layers
The most useful application of all three properties is deciding which pigment goes in which layer of a multi-layer painting.
For an early wash that you will paint over later, transparent and low-staining pigments give the most flexibility. Transparent pigments let subsequent layers glow; low-staining ones can be partially lifted if the first wash goes wrong.
For a final shadow glaze, transparent staining pigments are ideal. They deepen the tone without muddying the colors below. Phthalo Blue or Quinacridone Magenta work well here.
For sky and atmospheric areas, granulating pigments add natural texture without needing any technique tricks. A loose wash of French Ultramarine in a sky will granulate on its own.
Understanding how warm and cool versions of your primaries interact with these properties makes the whole system click into place. The article on warm and cool primaries explains that concept, and once you combine it with pigment properties, color mixing starts to feel predictable rather than accidental.
For building a starting palette that gives you a range of transparency and granulation levels without buying too many colors, the guide on how to build a limited watercolor palette and why it helps is a good companion read.
Frequently Asked Questions
Do I need professional paints to get these effects?
No, but student-grade paints sometimes blend multiple pigments into a single color, which makes the staining and granulation behavior harder to predict. Single-pigment colors, marked with one pigment code like PB29, behave more consistently and are easier to learn from.
Can a single color be both staining and granulating?
Yes. French Ultramarine (PB29) granulates heavily and has moderate staining. Understanding that a color has both properties helps you predict exactly what it will do in a wash or mix.
How do I know if a color I already own is a heavy granulator?
Paint a loose, well-watered swatch on cold-press paper. Let it dry completely without tilting or touching it. If the dried swatch shows visible texture, speckle, or a mottled pattern, it granulates. If it dries smooth and even, it does not.
Is opacity always a problem?
Not at all. Opaque pigments like Titanium White or Chinese White are useful for adding highlights on top of dry layers, especially on toned paper. Cerulean Blue's slight opacity gives sky washes a soft, hazy quality that more transparent blues do not have. The key is choosing opacity on purpose rather than by accident.
Can I test these properties before buying new paints?
Most art stores have color charts or sample sets. You can also find free swatch comparisons on manufacturer websites. Doing a quick set of test swatches on your own paper with your own water is more reliable than relying on printed or digital color charts, since those do not show texture or lifting behavior. The beginner's color wheel guide also walks through practical swatch-making as part of learning color relationships.