Mud is a perfect material for art and architecture; it’s durable, beautiful and easy to work with. Earth is used by many cultures for building — in fact, it’s the most common construction material on the planet. For comfort, beauty, ease of use, ecology and economy, it beats most other materials hands down. While earthen accents are easy to incorporate into new cob or straw bale walls, you don’t need to build a brand new house to enjoy them. Whether you have sheetrock, masonry or even wood walls, mud can add texture, color and warmth to any interior. All the examples shown here were made with basic clay plaster mixtures, and reflect the artistry and lives of their makers. And don’t worry if you’re not an artist; if you can make mud pies, you can make art out of earth!
Earthen plasters add life to a building. There’s a reason a so-called “perfect finish” is often referred to as “dead” straight, or “dead” flat — dead surfaces don’t move. When every inch of a wall is the same, there’s no variation of light, shadow, texture or color. But as you walk past a hand-plastered wall, you notice shifting light and shadow — it lives! Rather than just connecting corners, sculptured walls literally shape space. Living, handmade plaster walls embrace you.
Earth is easy to sculpt, and sculpture need not be complicated. Mud makes it easy for anyone to make beautiful textures, patterns and lines. Just rounding a corner or building up edges at doors or windows helps define a room. Extending the play of light from a flat wall into the third dimension removes the division between sculpture and architecture.
Designs shown on these pages were made of clay subsoil, sand, fiber and additional binders as needed. Sand and fiber help control drying and cracking, while binders add workability, strength and resistance.
Small decorative earthen accents are relatively easy to make. Consider making a drawing on graph paper first, but if drawing makes you nervous, just start playing with mud on a piece of sheetrock. For a large mural, try enlarging the design on a grid, it’s easy and it teaches proportion. Divide the design in half or into quarters, then copy it section by section until you’ve recreated a larger version.
The Many Faces of Mud
Just like people, mud varies. Still, a few basic principles and some practice can make you an expert artist of your own soils, techniques and recipes.
The term “plaster” is generic, and applies to everything from real, under-your-feet mud, to gypsum plaster (also called “plaster of Paris” or “casting plaster”), to traditional African mixes of manure and clay, to stucco (the old fashioned kind made of lime and sand, or the post-World War II type made with cement). Earthen plaster is merely “clayey” subsoil mixed with sand and fiber. Clay is the primary binder, while sand and fiber limit cracking. Any mud can be “plaster,” and most plasterers call their material “mud.”
A well-finished plaster won’t rub off easily and can be cleaned. If you have pure fine clay soil and “sharp” quartz sand, your mud will be quite tough and hard. If you have silty soil and soft, “round” sand, your plaster will be more vulnerable.
Earthen art can be further cemented and stabilized with binders. One approach is to mix sticky stuff like lime putty or wheat paste directly into the plaster. The other approach is to paint a penetrating wash, such as casein, whitewash or sodium silicate, over dry plaster.
Most plaster sticks well to most surfaces, though texture is often helpful, and sometimes necessary, depending on the thickness of the mud. Texture on a wall helps thick plaster stick — the thicker and heavier the layer, the more surface texture you’ll need for it to stick well. A thin plaster sticks beautifully to plain or painted sheetrock, with little or no prep. It’s also easily applied to most masonry, such as brick, stone or block. I even have applied it successfully to masonite and glass. Very fine mud works best on a smooth surface. Mud sticks to wood too, but because wood swells and shrinks, it must be covered with a layer of tar paper or other waterproof barrier, followed by a textured material for the wood to grab onto. Otherwise it cracks and falls off when the wood moves.
Maintenance needs vary, but the beauty of mud is that “worn” surfaces made of natural materials often look more interesting than fresh ones. Look at our love affair with ancient buildings. Traditionally, old buildings were maintained with a fresh coat of lime wash or other natural paint which, over the years, produces a “patina of age” that can’t be faked.
Colors can be mixed into the plaster itself or applied to finished surfaces. Try colored earths if you have any around your area — they’re especially common in the Western states. I collect natural earthen color pigments when I see them in road cuts or construction sites. Various shades of yellow, orange, red, brown and black all are common around my home in central Oregon. However, if you don’t have easy-to-get color underfoot, concrete pigments work well (Davis Colors, for example), and often are composed of various iron oxides that are quite potent in small amounts, and relatively cheap at builders’ supply stores. (Be aware that some blues, yellows and greens, especially those used in potters’ glazes, can be highly toxic; some contain heavy metals and pose hazards even just with skin contact.)
The Price of Creativity
What does it cost to add earthen accents to your home? Well, how long is a piece of string? If you hire a contractor and buy commercial products, the costs could mount to the point at which a deluxe paint job starts to look cheap. If you do it yourself with local mud and sand, you may spend nothing. Your best bet is to take the time to experiment and play. Prove the truth of my favorite quote, “An artist is not a special kind of person, every person is a special kind of artist.”
An Earth Plaster Recipe
- One part “clayey” subsoil
- Three to four parts sand
- Just enough water (too much causes slumping and cracking)
- One half part fine fiber, quarter inch or less is best for detail work and thin plasters, but anything works, from cow or horse manure; to chopped grass or straw; to horse or human hair.
Mix all of the above in a wheelbarrow, bucket or the like, using your hands, a shovel or power tools. Remember, it’s easier to add water than to take it away! I make my plaster a bit wetter than peanut butter, and adjust as I go. The finer your materials, the finer your plaster. Remove coarse materials by sifting through a window screen or quarter-inch hardware cloth.
Then smear the mud on by hand, with masonry trowels or any other tool you can think of. You can go up to about a half inch thick before you’ll start having trouble with cracks and slumping. For more thickness, apply multiple coats, add longer fiber and give it some textured surface to “grab” onto. Try texturizing with small sticks or reed mats, mason’s lath, coarse burlap glued and pegged on, twine wrapped and tied around nails, etc.
Use circular strokes to smooth the surface. Try different tools for different effects — from deep finger and hand prints, to subtly undulating strokes of your palm. Wood gives a softer finish, metal a harder polish. A tool held perpendicular to the mud will make a ragged line, but at a low angle, it will make a clean line. Scratch or carve in a design using forks, knives or spoons — experiment! Adjust the recipe “to taste.” See “Get Muddier!” below for more details.
Get Muddier! Books and Printed Materials
Dig Your Hands in the Dirt: A Manual for Making Art Out of Earth
By Kiko Denzer (Hand Print Press, 2005)
Details on Denzer’s earthen mural projects.
Build Your Own Earth Oven
By Kiko Denzer
Combine the utility of a wood-fired oven with the ease of earthen construction.
The Hand-Sculpted House
By Ianto Evans, Michael G. Smith and Linda Smiley
Everything you need to know to build an earthen building, including plasters.
The Last Straw Journal
Detailed information on various techniques and materials can be found in the following back issues: Issue #43: “The Case for Clay,” Issue #33: “Earth-Cement Plaster” and Issue #29: “Selecting Lime Products.”
The Natural Plaster Book
By Cedar Rose Guelberth and Dan Chiras
Guelberth also operates the Building for Health Materials Center, which supplies plastering tools and materials.
Because this field is expanding rapidly, Denzer recommends conducting a Web search to locate workshops on specific topics, such as plastering or finishes. Also check out these organizations:
The Natural Building Network
A good resource for finding expertise local to your region, as well as consultants, teachers and contractors.
Cob Cottage Co.
Since 1993, Cob Cottage has taught hundreds of workshops on natural building.
Workshops on cob and natural building.
Kiko Denzer has been an earth artist since 1994, when he attended a cob building workshop. He made ovens first, and sculpture followed naturally. Then he got various mud jobs: at a restaurant making ovens, designing garden walls, doing interior plastering, as well as various school projects, gallery shows and community installations.