I’ve been thinking about painting my back porch and deck white since it was built last summer. After all, we spend about fifty percent of our time out there. I’ve long disliked the toxicity of commercial paints on the market. Most common indoor and outdoor household paints contain volatile organic compounds (VOCs). VOCs contain a variety of chemicals, some of which give off noxious fumes and may have short term or long term adverse health effects. According to the EPA, levels of some VOCs are 2 to 5 times higher inside a home than outside; when you are painting or stripping paint in your home, particularly in older homes where lead paint may have been used in the past, indoor levels of VOCs may be 1000 times that of outdoor levels. I’ve used VOC-free paints for all of my indoor and outdoor painting since they came on the market some years back.
In thinking about my outdoor living area, I wanted to investigate additional ways to paint more safely, and came across two options that I could possibly make myself: whitewash and milk paint. Whitewashing, which many of us remember from Tom Sawyer whitewashing the fence in The Adventures of Tom Sawyer, was commonly used for years because it is inexpensive, can be homemade, and homeowners could use ingredients they had on-hand, improvising their own recipes. It is still used in rural areas to protect wooden surfaces like fences and barns, or by designers who want to give furniture a rustic look. The mixture’s base is always lime and water, which makes a chalky type of plaster. Then, ingredients might be added to thicken or strengthen the mixture, like flour, glue, sugar, soap, soil, or milk.
One of the downsides of using whitewash to cover a surface is that it takes a few days to cure. Until cured, it has almost no sticking power. Even then, whitewash can sometimes rub off on clothing or other surfaces, even years after painting. It adheres fairly well, however, to porous substances like adobe. Other outdoor whitewashed surfaces, like barns, are often painted with many coats for a more long-lasting coverage. This is why you may see white barns or fences that have flaking exteriors; though one layer may flake away, there are other layers beneath to maintain coverage. However, whitewash does not offer the greatest protection against rain damage, since repeated exposure to moisture will gradually saturate its natural ingredients.
10 pounds hydrated lime
2 gallons water
3 pounds salt
2 – 5 gallon buckets
Using a large spoon, mix 10 pounds of hydrated lime with 1 gallon of water in an extra-large bucket. Add more water if needed to make a thick paste.
In a second bucket, mix one gallon of warm water with 3 pounds of salt and stir until dissolved.
Slowly add the salt water to the lime mixture, stirring well. If mixture is too thick to apply with a paint brush, slowly add additional water to thin to the desired consistency.
If covered tightly, you can store whitewash for several days in a cool place.
The second alternative to traditional paint is milk paint. Milk-based paints have been used for over 20,000 years and have been found on ancient cave walls. When King Tut’s tomb was opened in 1924, artifacts inside were found to have been painted with milk paint. Almost all early American furniture prior to the Civil War was painted using this technique. After the Civil War, commercial oil paint was developed. It was easier to store and ship, since its shelf life wasn’t limited; milk paint will spoil in the same manner as whole milk.
From what I understand, this covering is durable because the milk contains casein, a protein that hardens as it dries and adheres well to wood, plaster, terra cotta, and clay. When applying to wood surfaces or plaster walls, milk paint is supposed to be self-priming, which removes a time consuming step from the painting equation. The first coat may be slightly uneven, due to the texture of the paint, so it is recommended to apply the second coat immediately after the first for a smoother finish. The finish will be translucent, but the opacity increases with each coat you add. As you might expect, milk paint has a slightly milky odor when first applied, but this odor fades as the paint dries.
I was given this recipe for milk paint which seems a lot like cheese making:
1 quart skim milk
Strainer or sieve
Dry color pigment (optional)
Mix the juiced lemon with 1 quart of skim milk in a bucket and leave the mixture overnight. (Sitting at room temperature causes the mixture to start curdling.) The next morning, pour the mixture through a strainer or sieve lined with cheesecloth to separate the solids and whey.
To give color to your paint, you may choose to add four or more tablespoons of dry color pigment to the curd and stir until the pigment is incorporated. Continue to add color pigment, stirring constantly, until you achieve the desired hue (Be sure to wear a mask when using dry pigments and/or follow the manufacturer directions.) .
Milk paint will spoil quickly, so it should be applied to your surface within a few hours of mixing. The recipe above makes a small batch, so you will want to test this on a smaller project to get started.
The first milk paints were dyed with pig’s blood, but, luckily, these days you can buy both natural pigments and the color pigments mentioned in the recipe above in a range of shades. You can also experiment by leaving steel wool in a dish of water and adding the resulting rusty water to your paint; simmering blackberries on the stove and straining the liquid; brewing and adding strong coffee for the desired shade of brown; or adding store-bought juice concentrates to your paint.
You may also buy milk paint already mixed and ready to go. Personally, I’m not really sure how I will finally choose to seal this wood. But, no one – even the ancient Egyptians – has been able to provide a recipe for keeping carpenter bees at bay. If you have any suggestions (for paint or bees) or experiences (good or bad), please share them in the comments below. In the meantime, I will keep researching my options and perfect my Tom Sawyer-style pitch to get the neighborhood kids excited about painting. Of course, such a specialized job can only be done properly by one in a thousand, maybe one in two thousand people…