Natural Finishes

Image courtesy of Tempe Sikora, www.rarestbloom.com

Paint consists of pigment, binder, filler and solvent and can easily be made from natural, non-toxic ingredients.  Like plasters, natural paints should be breathable so that moisture can easily evaporate from the wall.  Pigment can be derived from natural sources either directly or from commercial powder derived from natural sources.  Plants, insects, minerals, and iron oxides work well.  For example, madder root (Rubia tinctorium),[1] the dried insect Dactylopius coccus (feeds on prickly pear and torch thistle cactus),[2] and iron oxide are all used for reds and crimsons; the medicinal indigo shrub (Indigofera tinctoria)[3] can be used for indigos, and chrome oxide for greens.  Binders include starch (typically from flour), casein (milk protein), and linseed oil (from flax seeds).[4]  Fillers add bulk to paint and can be made from chalk, clay, talcum, limestone, silica or marble.

Several common natural paints that we love to work with include:

• Flour Paint: Clay is typically mixed with flour, and increases the binding ability of the starch. Basic flour paint is comprised of flour, clay and water.[5]   Produces very thick paint and can be uneven unless smoothed with a damp sponge or brushed after the coat is partly dry.
• Casein Paint: Made from nonfat milk, lime, water, and filler (usually whiting).
• Lime Wash:  Pure slaked lime mixed with water. Produces a stunning glowing finish because of the refraction of calcite crystals.[6]  It is washable, durable, and has antibacterial properties.[7] Important to note that opacity increases as it dries.
• Milk Paint: Made from quark and borax.  Dries hard and glossy, is water repellant, and produces thin, pastel colors.[8]
• Egg Paint: Consists of linseed oil, water, pigment and egg yolk.  Egg paint produces deep, solid colors, but smells strong, and has to be mixed in small batches, making it best suited for bright detail work.[9]
• Quark and Oil Glaze: great for sealing flour paint.

Linseed oil is made from flax seeds and can be used as a natural wood varnish; however, raw linseed takes a long time to dry and does not prevent mildew.  To improve the performance of raw linseed, chemical additives are mixed in, affecting the environmentally benign nature of the oil itself.  Another natural oil that can be used to coat wood is Tung oil, derived from the nuts of the Tung tree.  Tung oil dries much more quickly than linseed oil, doesn’t require the same additives, and does not darken with age.