Why I Love Plaster as an Architectural Finish

If you have not experienced a room finished out in natural plaster and earth ground pigment, you don’t know what you are missing. Or perhaps you have been in such a room, and felt a difference, but couldn’t quite put a finger on it. The energy feels different, the air cleaner, the sound clearer, and of course, the aesthetics!

I remember when I stepped down into a subway station in Rome, Italy for the first time. I was struck by the lime plaster on the walls. As I felt the smooth glossy walls run under my fingers, I looked up into the arches to see the sweeping motions of the plasterer’s trowel stuck in time, mottled out in varying shades of a beautiful ochre. I laughed as I thought to myself what this type of finish would cost in the United States, and here it was beautifying the subways of Rome. (I can only imagine what the Italians thought of the tourist rubbing down their subway walls, and I chuckle to this day.)

A plaster finish is something that has been with humanity for thousands of years. (9,500ish years to be more precise, go ahead Google it. Trust but verify.) While the type, texture, color, and finish may change with the plaster type and the applicator, one thing does not: its variation, or mottling. The beauty of a plaster lies within its variation as color moves from light to dark. As if the plasterer moved the gradient with each pass of their trowel. This speaks to our deepest soul. Our eyes did not evolve to see monochromatic hues stretched in plastic across our walls. And we certainly did not evolve to be surrounded by sheets of “Hunting Coat Red and Antique White.” Our eyes have evolved with the natural world, always seeing the subtle changes of an arching sky, the gentle color sweeps in a leaf and the stepped fade in color from one ridge to the next as they recede to the horizon. A plastered wall speaks to that evolution, and draws our eyes to its subtle variation and that is comforting to an eye bombarded by screens and the empty promises of “Swiss Coffee.”

Another thing that draws me in on a plaster finish is the smell, and the freshness of a plastered room. Clay plaster and lime plaster have two very distinct smells, but they are both a very pleasant, earthy, sweetness. The initial weeks after a fresh coat of plaster goes up are intoxicating, in the best of ways, (we’ll compare this to the in-toxic-ating ways of latex paint later), and the subtle effect of plaster lasts much. A plastered wall breathes. It absorbs humidity. It is naturally anti-microbial due to plaster’s pH, and it does not hold a static charge. I believe this affects how fresh a room can feel. When we step into a room with latex paint on the wall, we are stepping into a sealed chamber, and it feels just like that: stale, stagnant, sterile, and stuffy. That positive charge in a plastic paint attracts and holds dusts to the wall; not so with lime or clay plaster. A plastered wall feels fresh, lighter, and more welcoming.

Speaking of feel: reach out and touch a natural plastered wall. Run your fingers over it, go ahead, no Italians are watching, I promise. A plaster wall invites touch, whether its texture is rough and gapped (as in a skip trowel) or smoother than polished marble, we want to feel it. The tactile feel of plaster cannot be overstated, its texture speaks to us. It should feel like home as earthen plasters have been used in shelter since we decided to “make the cave.” They have changed and matured as our building prowess and aesthetic have matured, but the base material is still clay, or lime mixed with sand, and water.

Clay and lime-based plasters also carry many advantages over modern latex and acrylic paints. Not least of which are their health benefits. Earthen plasters are naturally zero VOC and don’t contain biocides or plasticizers, because they naturally perform the functions of those additives. “What about the environmental benefits?” Those are topics for future posts. What’s most important right now, is simply knowing that natural plasters have been time-tested over thousands of years. They are healthy, durable, building materials that should be used whenever possible; modern paint, like all plastic, is a by-product of the petroleum industry. They have been used for perhaps 100 years and it seems every 20 years or so, some new toxicity is exposed in modern paint that must then be formulated out (see lead, see mineral spirits, see various plasticizers, et al. Next up see crystalline silica). Modern paint is still very much in the experimental stage when it comes to its effects on human health.

I’ll get this out in the open now, I’m old-school when it comes to building. I think the technological breakthroughs in plastics should stay out of our homes as much as possible. That’s not to say there aren’t some exceptions, as surely there are, however with the amount of synthetic toxins we are exposed to daily, it sure is lovely to walk into a home or a room with elegant materials, time-tested over thousands of years. Lime. Wood. Clay.