The Lascaux Sirius Primary System Explained

Founded in 1963 by Alois K. Diethelm in collaboration with professional artists, Lascaux pioneered the first acrylic paint made in continental Europe. Over the past 30 years, under the leadership of artist Barbara Diethelm, Lascaux has expanded its expertise and innovation to become a leading Swiss manufacturer of premium acrylic paints and mediums. Inspired by the prehistoric cave paintings found in Lascaux, France, they are committed to long-lasting quality, consistent colours, and reliable performance. These values have made Lascaux trusted by artists and creative professionals worldwide.

In this article, Barbara Diethelm explains the innovative Sirius Primary Colour System – a patented colour mixing system that relies on five primary colours instead of three. She delves into the development, colour theory, and unique philosophy of the Sirius Primary Colour System.

How the Lascaux Sirius Primary Colour System Was Developed

As both an artist and paint manufacturer, I have long been fascinated by colour and its harmonies. In 1995, I developed a Five-Colour Theory based on five primary colours that produce the widest range of pure hues and, when mixed equally, create a neutral black. This system was patented by the European Patent Office in 2001.

For over 30 years, the Sirius Primary System has offered artists two water-based paint ranges – watercolour and acrylic – built on this concept. Using just five colours, an unlimited spectrum of pure, vibrant, and harmonious colours can be mixed for applications in art, design, education, colour theory, and architecture. The simplicity of the system makes colour mixing accessible, enjoyable, and highly economical.

I am often asked: What are the most suitable primary colours? How can a wide colour range be mixed from only a few colours? And why is there such a gap between colour theory and practice? These questions reflect the same challenges I faced during my studies. Most painters find that mixing with only three primaries rarely produces satisfying results or an even colour wheel, highlighting the disconnect between theory and reality. My search for a colour system that was both theoretically sound and practically effective ultimately led to the development of the Five-Colour Theory and, in 1995, the Sirius Primary System.

Artists need precise, predictable colours to mix exact hues consistently. This is especially important when colour is used therapeutically, where specific frequency ranges must remain constant. Modern pigments, with their accurately defined wavelengths, are ideal for creating precise colours. However, a paint’s properties depend not only on the pigment but also on its complete formulation. In the Sirius Primary System, the key challenge is not just producing each colour, but ensuring that all five primaries work together as a coherent, harmonious system.

Consistency of Theory and Practice using the Sirius Primary System

The Sirius Primary System uses five primary colours – Magenta, Red, Yellow, Cyan, and Ultramarine – creating a broader and more nuanced colour range than the traditional three-primary systems. Their purity and balanced relationships produce clear, vibrant harmonies, while equal parts of all five mix to form a rich neutral black. An additional White rounds off the system. The colours maintain their chroma in unlimited ranges of mixtures: from secondary and tertiary colours to earth and pastel tones.

By including warm and cool versions of red and blue, the Sirius Primary System offers greater control over colour temperature. With Magenta and Cyan as cool primaries, Red and Ultramarine as warm primaries, and a neutral Yellow, artists can create balanced palettes and mix colours that feel warm, cool, or neutral.

The Sirius Pentagon includes five secondary colours derived from the primary colours, with complementary pairs positioned opposite each other for easy identification. At its centre is a neutral black, created by mixing all five primaries in equal parts – demonstrating the system’s balance, coherence and alignment. Patented by the European Patent Office in 2001, the Sirius Primary System extends traditional three-colour theories by enabling cleaner, more accurate colour mixing. Together, Sirius black and white provide a full light-to-dark scale, from vibrant pastels to rich, deep tones.

The Joy of Easily Mixing an Unlimited Range of Vibrant Hues with the Sirius Primary System

Mixing black from the five primaries is a creative exploration that often reveals a rich range of greys and earth tones. Whether achieved immediately or discovered through experimentation, the resulting colours remain vibrant, brilliant, and highly saturated. Rather than prescribing fixed mixing formulas, the Sirius Primary System is designed to encourage exploration and creativity. It demonstrates how clean, harmonious colour mixtures can be achieved while leaving room for personal discovery, experimentation, and the joy of colour mixing.

The pure, luminous colours make it easy to create and distinguish a wide range of hues. Even a single drop can transform a mixture, making colour mixing intuitive, inspiring, and rewarding for artists of all levels. Because the five Sirius Primary colours are precisely aligned to each other, they always yield pure and clear colour mixtures.

To motivate people who are inexperienced in colour mixing, we developed an easy, playful method. This ‘drop mixture method’ can be employed loosely, by using a drop as the measure, or more precisely, by utilising an exact part. For example, equal parts of Red and Yellow yield the secondary colour orange and playing with the ratios of these two primaries opens up a range of orange tones. Similarly, when one mixes White with Magenta or Red, one can generate a range of pink shades. Increasing the ratio of red drops yields redder mixtures.

With this simple mixing method, over 78,000 harmonious hues can be created while maintaining colour intensity (chroma) and clarity. This is especially noticeable when mixing subtle earth and pastel hues or when a colour is lightened with Sirius White or darkened with Sirius Black. Even in tints and shades, the colour tones retain the greatest possible colour constancy and chroma. From vivid brights to subtle earth tones, pastels, tints, and shades, a rich palette can be achieved from just a few source colours.

Colour mixing is central to the creative process, often more so than applying paint. It encourages imagination, expression, and intuitive exploration of hue. Difficult early experiences with dull or ‘dirty’ results often discourage experimentation, but these reflect limitations of the colours rather than the user’s skill. With luminous, pure colours, mixing becomes simple, rewarding, and inspiring for artists of all levels. The balanced five primaries of the Sirius System produce consistently clean, luminous colours, encouraging confident and joyful colour exploration. Suitable for all ages, it supports both strong and subtle image-making outcomes.

The harmonious and nuanced range of vibrant hues stimulates colour sensitivity. As perception shapes awareness, refining the way we see colour expands both our perception and our awareness. Working with subtle variations strengthens the ability to distinguish more colours, deepening both learning and awareness. The sensual nature of colour reaches beyond the mere visual. In a painting by Swiss artist Vera Deforet, the intuitive use of the Sirius colours creates a sense of coherence, where all parts resonate together in visual harmony.

A deep appreciation of the complex sensual nature of colour is essential where it shapes physical, emotional, and even spiritual experience – in fields like architecture. The Sirius Primary System’s transparent, luminous colours are ideal for glazing techniques, creating harmonious, vibrant spaces. Their high intensity also means that only a thin coat of paint is needed for effective results.

Their luminosity, purity, and balance enable precise mixing of a wide range of harmonious colours, supporting deeper exploration of colour relationships. This subtle differentiation enhances perception and offers therapeutic value in settings such as hospitals and clinics.

The above examples are but a few of the remarkably successful projects which have employed the Sirius Primary System. The range’s use in paintings, sculpture, and architecture demonstrates its versatility. The transparency and brilliance of the colours, often applied through glazing and washing techniques, bring depth to architectural spaces and create a joyful, radiant atmosphere. They show how a coherent colour scheme can be achieved using vibrant hues, and how maximum aesthetic value can be achieved through a minimal range of a few intense colours – in today’s challenging times, these can offer us the opportunity to experience beauty, harmony, and wholeness.

Further Reading

In Conversation with Barbara Diethelm, Owner of Lascaux Colours & Restauro

Artist Review of Lascaux Resonance Gold Gouache

A Modern Medium: A Brief History of Acrylic Paint

Colour Mixing: The Atmospheric Quality of Cool Palettes

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