The Colour of Light

Light has no colour of its own.

Colour appears only when light meets matter — when certain wavelengths are absorbed and others are reflected back to the eye.

On earth, plants are the primary translators of light into matter. Through photosynthesis, photons are converted into chemical bonds. Energy becomes structure. Time becomes substance. Every oil, resin, extract, and hydrosol begins here — as light, slowed down.

Olive oil is no exception.

The golden colour associated with olive oil — and with true Castile soap made from it — is not decorative, and it is not incidental. It arises from plant pigments formed in the olive fruit itself, shaped by sunlight, geography, season, and biology.

The dominant contributors are carotenoids — pigments such as beta-carotene, lutein, and zeaxanthin. These molecules absorb higher-energy blue wavelengths and reflect yellow–gold light back to the eye. They are the same class of pigments responsible for the colour of ripe fruit, autumn leaves, and many seed oils. In the olive, they are formed slowly, as the fruit matures under Mediterranean sun.

These pigments are fat-soluble and remarkably resilient. Even through saponification — the transformation of oil into soap — carotenoids persist. What changes is not their presence, but how light moves through them.

Alongside carotenoids are remnants of chlorophyll, and more often its transformed derivatives, pheophytins. Fresh chlorophyll is green, but under time, heat, and alkali it shifts toward warmer olive-gold tones. In liquid Castile soap, these compounds no longer announce themselves as green, but they subtly deepen and soften the gold, giving it optical depth rather than brightness.

Then there are polyphenols.

Polyphenols are not responsible for colour in a direct sense. Most are colourless or pale. But they play a quieter role: they protect what light has made. Polyphenols stabilise oils against oxidation. They slow degradation. They preserve clarity and vitality over time. In optical terms, they influence how “alive” or “flat” a colour feels — not by adding hue, but by defending it.

In a well-made liquid Castile soap, these elements come together within a translucent structure. Light passes through the liquid, scatters within its micellar system, and returns altered — not blocked, not masked, but filtered. The result is neither opaque yellow nor artificial brightness, but something closer to what we recognise intuitively as sunlight made visible.

This is why the colour matters.

Not because it is attractive, but because it is evidence.

No dyes are added. No colourants are required. The hue emerges from the oil itself — from pigments shaped by the tree, preserved through restraint, and revealed again through process.

What you are seeing is not “gold” as ornament.

It is light that has lived inside a plant.

At Phytocea, this understanding matters because it defines how we formulate. We work with materials that already carry structure, energy, and history. Our role is not to improve them, but to avoid damaging what is already there. Precision, patience, and discipline are not aesthetic choices — they are functional necessities if light is to survive the journey from tree to skin.

The colour of our soap is not a branding decision.

It is the natural consequence of working with living materials and allowing them to speak.

This is what light looks like when it has been absorbed, transformed, and returned.