A tube labelled with a familiar colour name can look like an easy replacement. Yet oil paint colour equivalents are rarely decided by the name alone. Two paints called Ultramarine, Crimson Lake or Naples Yellow may differ markedly in pigment, opacity, undertone, tinting strength and behaviour in a mixture. For painters who want a palette that remains dependable from sketch to final glaze, those differences matter.

Why oil paint colour equivalents are not exact matches

Colour names have a long and imperfect history. Some refer to a particular pigment, such as Cobalt Blue or Burnt Sienna. Others describe a historical appearance, a regional association or a colour family. Terms such as hue, lake and deep can add further ambiguity. They are useful descriptions, but they do not tell the whole material story.

The most reliable starting point is the pigment index name and number. A single-pigment paint tells you precisely which colourant is doing the work. For example, French Ultramarine is commonly based on PB29, while Phthalo Blue may be PB15. Both can occupy the blue area of a colour wheel, but they differ profoundly: ultramarine is warmer, granulating in some media and relatively moderate in tinting strength; phthalo blue is cooler, intensely strong and often more staining in mixtures.

A paint made from several pigments can still be excellent, particularly when it has been formulated to achieve a historic colour or a specific practical balance. It is simply less predictable as a direct equivalent. When replacing a multi-pigment colour, compare the complete pigment list rather than matching the mass tone on the tube or colour chart.

Colour appearance is only one part of the decision

A convincing equivalent must work in the same role in your painting. That role may be a transparent glazing red, an opaque pale yellow for landscape light, a quiet neutraliser or a powerful blue for clean green mixtures. The replacement does not need to be chemically identical, but it should meet the needs of the passage you are painting.

Consider opacity first. An opaque substitute can cover a dark underlayer where a transparent original would allow it to influence the result. This is particularly evident with yellows, earth colours and pale blues. A transparent paint, by contrast, may be ideal for luminous layering but disappointing when used to establish a solid note of colour.

Undertone is equally significant. A red can appear rich and balanced in a thick brushstroke, then reveal a distinctly blue, pink, orange or brown bias when pulled out thinly with white. Testing a small tint is often more revealing than judging the full-strength colour. The same applies to blacks and earths, whose hidden temperature can alter a whole mixture.

How to compare oil paint colour equivalents

Begin with the function of the colour you are replacing. Ask what it does in your current palette and paintings. Is it the only transparent warm red? Does it make the greens you rely on? Is it a convenient flesh-tone modifier, or an earth that quietly unifies a landscape? A useful equivalent preserves that function, even if the tube colour is not visually identical.

Then compare four practical characteristics: pigment composition, transparency or opacity, colour bias and tinting strength. Drying behaviour is a fifth consideration when working in layers. Some pigments dry relatively quickly, while others may remain open longer; this can affect both your painting rhythm and the order in which layers are applied.

The following distinctions can help when assessing a candidate:

• A single-pigment replacement is often the clearest choice when clean, controllable mixtures are required.
• A hue may be a practical alternative where an historic pigment is unavailable, costly, less lightfast or unsuitable for your studio requirements.
• A stronger modern organic pigment may need far less paint in a mixture than the colour it replaces.
• An opaque equivalent can be valuable for direct painting, even where it cannot reproduce the glazing behaviour of the original.

Do not assume that a pigment with the nearest name will be the closest match. Viridian and phthalo green, for instance, are often discussed together because both can produce cool greens. Viridian is usually quieter, more restrained and less forceful in mixtures. Phthalo Green is exceptionally powerful and can dominate a palette unless used sparingly. One is not a lesser version of the other; they offer different decisions at the easel.

Test the paint in the way you actually work

A small studio test is more useful than an isolated swatch. Paint each colour at full strength beside the other, then make a tint with the same white in the same proportion. Pull out a thin wash with a little medium, if glazing is part of your practice. Finally, mix each with the colours it meets most often in your work.

For a landscape painter, that might mean testing a yellow with a blue for greens and with an earth for sunlit neutrals. For portrait work, test a red or yellow in a flesh mixture, then assess whether it remains natural when modified with white and a cool blue. Abstract painters may be more concerned with whether the substitute holds its identity beside a high-chroma neighbouring colour.

Let the tests dry before making a final decision. Oil colours can shift subtly as the surface settles, and gloss differences can make a wet comparison misleading. Label the panel with pigment information, not only colour names. Over time, it becomes a practical record of how your chosen materials behave together.

Common equivalent questions on the palette

Historical reds are a frequent source of confusion. A colour named Alizarin Crimson may refer to traditional natural alizarin, a modern synthetic alizarin pigment, or a permanent substitute made from different red and violet pigments. These paints can share a deep crimson appearance, but their lightfastness, transparency and mixing character may not be interchangeable. If permanence is essential, inspect the pigment information and test the colour in thin glazes as well as tints.

Cadmium colours require a similarly careful comparison. A cadmium-free yellow or red may offer excellent brightness and lightfastness, but it will not necessarily reproduce the opacity, density or subdued mixing quality of a cadmium pigment. For some painters, a more transparent and cleaner-mixing substitute is an advantage. For others, particularly those building form with opaque passages, the traditional pigment’s covering power is central to the result.

Earth colours also deserve more attention than their quiet appearance suggests. Burnt Umber, Raw Umber, Yellow Ochre and Sienna colours vary in temperature and opacity between formulations. A replacement may be close enough for blocking-in yet alter the warmth of a shadow mixture or the speed at which a layer dries. If an earth is structurally important to your process, compare it as carefully as a bright blue or red.

Build a palette around roles, not tube names

A well-organised palette does not need every apparent equivalent. It needs colours with distinct jobs. A warm and cool version of each primary may be helpful, but the exact arrangement depends on your subjects, working method and preference for mixing versus convenience colours. A limited palette can produce extraordinary range when its pigments are well understood.

When a familiar tube is unavailable, begin by identifying whether its contribution is temperature, transparency, opacity, mixing clarity or convenience. You may find that two existing paints can replace it more effectively than one near-looking substitute. A transparent warm red plus a cool violet, for example, may offer more control than a ready-made crimson whose pigments pull mixtures in several directions.

Michael Harding’s Colour Compare and Equivalent Finder tools can provide a useful first comparison by bringing pigment information and colour relationships into view. Use them as a point of enquiry rather than a substitute for a painted test. Your ground, medium, white, brushwork and preferred layer structure all affect what an equivalent means in practice.

The most satisfying replacement is the one that makes your palette more intelligible. Keep a record of the pigments that earn their place, test unfamiliar colours without expectation, and allow the painting itself to decide whether a near match has become a better choice.