Systems & Finishes - V·04
Clay plaster.
Unfired clay, sand and natural fibre. The softest surface we install and the only one that actively regulates the humidity of the room it is in.
Clay plaster is not fired, not cured chemically and not sealed. It dries and that is the whole process - which means it stays hygroscopic for the life of the wall. When a room gets humid, the clay takes moisture out of the air; when it dries out, the clay gives it back. In a bedroom the effect is measurable and most people describe it as the room simply feeling calmer, which is a vague thing to say but is consistently what we hear.
Visually it is the matt end of everything we do. No sheen at all, a soft velvet surface and a colour that comes from the earth pigment and the sand rather than from a tint added at the end. It absorbs light instead of returning it, so it makes a room quieter both literally - the texture takes the edge off hard acoustics - and visually.
Where it belongs
- Bedrooms. The humidity buffering and the sound absorption both matter most where people sleep.
- Living rooms and studies. Anywhere the ambition is calm rather than drama.
- Period and solid-wall property. Completely vapour-open, so it belongs on walls that need to breathe.
- Low-VOC and allergy-sensitive projects. No solvents, no biocides, nothing off-gassing.
Where it does not
Bathrooms, kitchens, hallways with a dog and anywhere with children at wall height. Unsealed clay is soft - it marks and it is not washable. That softness is not a defect, it is the reason it performs, but it does mean choosing the room honestly. In a family hallway we would specify Marmorino and be far more confident about how it looks in three years.
Repair is the compensation
Because clay never chemically sets, a damaged area can be re-wetted and re-worked and it blends into the surrounding wall in a way no cured finish can. A scuff that would mean repainting a whole wall can be dealt with locally in twenty minutes. We leave material at handover for exactly this.
Sustainability, without the marketing
Clay is dug, dried and milled. It is not fired, so the embodied energy is a fraction of cement or gypsum. At end of life it can be re-wetted and reused, or returned to the ground with no processing at all. We mention it because it is true and because it matters on projects chasing a genuine environmental standard - not as a slogan.
Questions we get asked.
Does clay plaster really regulate humidity?
Yes and it is the main technical reason to choose it. Clay is hygroscopic and never chemically sets, so it absorbs moisture from humid air and releases it again as the room dries. The effect is measurable and in bedrooms it is what people notice first even if they cannot name it.
Is clay plaster washable?
No and that is the honest limitation. Unsealed clay is soft and it marks. It belongs in bedrooms, living rooms and studies - not bathrooms, kitchens, or hallways with children or dogs at wall height. For those rooms we would specify Marmorino instead.
What happens if clay plaster gets damaged?
It is re-wetted and re-worked and it blends invisibly because it never cured in the first place. A scuff that would mean repainting an entire wall can be dealt with locally in about twenty minutes. We leave material with you at handover for exactly this.
Is clay plaster suitable for allergies or chemical sensitivity?
It is among the most inert finishes available. No solvents, no biocides, no VOCs, nothing off-gassing - the ingredients are clay, sand, natural fibre and mineral pigment. It is a common specification on projects where indoor air quality is a stated requirement.