What does mould look like? Black, green, white & orange explained

What mould actually is

Mould is a type of fungus. It grows from microscopic spores that are always present in the air around us. Given moisture, a suitable surface and a little warmth, those spores settle and grow into the patches you can see. The colour of the patch depends on the species, the material it's growing on, and how established the colony is.

What every type has in common is this: mould is always a symptom of moisture. Identify the colour and location and you get a strong hint about the moisture source feeding it — and that is what you actually need to fix.

Black mould

Black mould is what most Cyprus homeowners find first. It appears as dark spots or a sooty coating on walls, window frames, silicone sealant and tile grout — especially in bathrooms, behind kitchen units and around windows. It's most often linked to condensation: warm, damp air settling on cold surfaces.

Black mould on grout or silicone is usually surface-level and cleanable in the early stages. Black mould that appears in patches across a wall, returns quickly after cleaning, or sits low down near the skirting may point to a deeper moisture source like rising damp or a hidden leak.

Green mould

Green mould tends to grow on damp organic materials — wood, plasterboard, paper, cardboard and fabric. You'll often find it under a leaking window, behind a damp wardrobe, on a water-stained ceiling, or on furniture that has been wet. Green patches that spread across a wall or ceiling usually mean the material itself has taken on water and is staying wet long enough to support a colony.

Unlike surface condensation mould, green growth on plasterboard or wood often means the material is damaged and may need to be removed rather than just cleaned.

White mould

White mould often looks fluffy or powdery, like a fine dusting of flour. It favours damp, poorly ventilated spaces — under floors, in cupboards, on stored clothing, and on the back of furniture pushed against an outside wall. It's easy to mistake for dust or efflorescence (the salty deposit left by evaporating water on masonry).

A simple test: efflorescence dissolves in water and feels gritty; mould smears and feels slightly fuzzy. White mould on fabrics or leather usually means the air in that space is too damp.

Orange and pink mould

Orange or pinkish patches most often appear in bathrooms — on shower curtains, grout, silicone and around drains. This growth is fed by soap residue, body oils and warm, humid air. It's generally less of a structural concern than black or green mould but thrives in the same damp conditions.

It tends to return quickly in bathrooms that never fully dry out, which is a sign that ventilation in the room isn't adequate.

Mould vs mildew vs dirt

These three get confused. Mould grows down into the surface it's on and can be black, green, white or orange. Mildew is a surface fungus, usually grey or white, that sits on top of damp materials and wipes off relatively easily. Dirt collects where dust settles and washes away cleanly without returning.

The tell-tale test is the return. If a mark reappears in the same spot within days of cleaning, it's mould — and it means moisture is still feeding it from behind.

When a patch is worse than it looks

The visible patch is often only part of the problem. Mould grows into and behind surfaces, so what you see on the wall can be a fraction of what's in the wall cavity, behind the plaster or under the floor. A small visible patch accompanied by a strong musty smell, blown plaster, or a tide-mark near the floor is usually worse than it looks.

If the patch is on an outside wall, near a window, or low down on a ground-floor wall, the moisture source could be condensation, a leak or rising damp — and each needs a different fix. An inspection from €75 measures the moisture in the wall, identifies the source, and tells you exactly what you're dealing with before you spend on the wrong treatment.