Transparent, Staining, and Granulating Paints Explained

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.

At a Glance

• Transparency controls how much light bounces back off the white paper; transparent colors glow, opaque ones sit flat.
• Staining pigments bond into the paper fibers and can't be lifted back out once dry; non-staining pigments rinse away.
• Granulating pigments have larger, heavier particles that settle into the paper's texture as a wash dries.
• A pigment can be both staining and granulating at once (French Ultramarine is the classic example).
• Single-pigment paints, marked with one code like PB29, behave far more predictably than multi-pigment student mixes.
• Match transparency and staining to the layer: transparent, low-staining pigments in early washes; transparent staining pigments for final glazes.

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. As the handprint guide to watercolor pigment attributes puts it, transparency comes down to particle size and how much of the paper layer the pigment actually covers, which is also why a thin, watery wash of an opaque color can still look fairly transparent while a thick, concentrated layer of the same paint turns chalky.

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). The mechanism is a matter of particle size: pigments with especially fine particles can work their way into the tiny gaps between paper fibers, where they lodge too deep to swab back out, which is exactly the behavior the handprint pigment attributes page describes when it explains why small-particle pigments stain and larger-particle pigments generally don't.

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.

That pigment code, like PB29 for French Ultramarine or PY43 for Yellow Ochre, is not a marketing label. It comes from the Colour Index, an international system that assigns every pigment a class (Pigment Blue, Pigment Yellow, and so on) plus a sequential number, so the Colour Index International reference on Wikipedia is worth a look if you want to understand why the same code shows up across completely different brands. Two tubes from different manufacturers with the same code are, in principle, made from the same pigment, which is why the code is a more reliable way to compare paints than the marketing name printed above it.

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. The ratings themselves are tied to a physical standard, not a manufacturer's opinion: ASTM lightfastness testing, as summarized by handprint, correlates each grade with the blue wool scale and an expected number of years of light exposure before noticeable fading, with Grade I meaning over a century of display life under normal conditions and Grade IV or V meaning a color that can visibly shift within a couple of years.

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.

Why do two tubes with the same pigment code look slightly different?

Manufacturers vary in how they mill and formulate paint, so particle size, binder ratio, and concentration can differ even when the pigment code matches. The code tells you the base pigment is the same chemical family, not that the paint will handle identically. It's still the most reliable starting point for comparison, but a swatch test on your own paper is what settles the question for a specific brand.

Does granulation mean a paint has more or less pigment?

Neither, on its own. Granulation is about particle size and specific gravity, not concentration. A well-loaded wash of a granulating pigment and a well-loaded wash of a smooth pigment can carry the same amount of color; one just settles unevenly into the paper's texture while the other lays down flat.