Whitewashing is one of those ideas that seems simple but has many layers once you get into it. When you want to whitewash interior brick -- a fireplace surround or an exposed brick wall, for instance -- you should begin at the end. Decide how much coverage you want on your brick, how little brick will be revealed by the white coating when you're done and, most important, how much work you are willing to do. Three different methods of whitewashing give you very satisfactory, if widely differing, results.
Light and Easy
Clean the brick surface to remove dust, soot and grease and provide a porous surface for your paint. Let the bricks dry so they will absorb the whitewash.
Mix powdered milk paint -- natural and nontoxic -- with water until it achieves the consistency of milk. Wipe the milk paint on the bricks with a paintbrush, brick-by-brick, and wipe some off with a damp sponge to leave an uneven film of white over the bricks. Experiment until you find the level of white you want.
Check the intensity of the white paint once your work dries and adjust the color by scrubbing off more paint with a wet sponge or by adding another thin coat of the watery milk paint.
Prepare the surface of the brick by cleaning it thoroughly. Lime wash is a mix of powdered, hydrated lime and water in approximately a 20 percent lime to 80 percent water ratio. It is a romantic coating, made from the ground coral and shells of ancient seas -- but its pragmatic value is that it covers well, is nontoxic and antibacterial, and is inexpensive. (see references 3, 4)
Put a painter's mask on to mix the powdered lime with water, to prevent breathing any airborne dust. Make a slurry the consistency of cream for thicker coverage, milk for thinner coats. Limewash will penetrate rough and porous brick while still allowing the brick to "breathe." (see reference 1)
Dampen the brick and, as the water is absorbed and begins to dry, apply the first coat of whitewash. Continue to dampen sections of the brick as you cover the area to be painted.
Work multiple thin coats of whitewash into the brick, using a special whitewash brush or any good quality paintbrush. Keep blending the edges of the painted areas into each other to avoid any lines where one section dried out before the adjacent section could be covered. (see reference 2)
Burnish the limewash into the brick with the paintbrush as you work, allowing the first application to dry before determining whether your coverage is transparent or opaque enough. Subsequent thin coats of whitewash will make the brick chalkier, smoother and whiter -- you may want limited coverage so some brick color and brick and mortar shapes show through.
Obliterate the brick look of the wall in a blizzard of plaster and paint that washes over the wall like a snowfall. The penumbra of the brick will show through the finish but the result is a wall of gleaming white sugar that shows no gaps, no mortar and no color.
Mix approximately equal amounts of plaster and joint compound together to make a thick, smooth paste. Trowel the plaster paste on a clean brick wall fairly thinly -- you want the surface of the wall to show but not its color. Allow the plaster coating to dry.
Sand the dried plaster with an electric hand sander -- if you have an artisanal and penitential bent, you can rub the plaster by hand with sandpaper -- to get a smooth surface. The more you sand, the more you reveal the brick.
Complete the whiteout with two coats of blinding white paint, a clean and unbroken finish over an unmistakable outline of the brick wall below.