Saturday, July 20, 2013

The Joy of Milk Paint

I've been working on a couple of shaker side tables with the hopes of selling them in one of the several galleries dotting the greater Richmond. It's great, because the side table offers a little practice in mortise and tenon joinery, dovetailing, half-blind dovetails, and working with proportions.
I know working with proportions sounds odd, but that's exactly what sets Shaker furniture apart from a generic, genre-defying piece. The most recent table I've completed has the drawer widened and the depth lessened to give it a little bit of airiness, but now that I think about it, it's probably an unconscious reaction to my second table I built that I have informally dubbed "crate on legs."
For the run of tables I'm building, I bought one board of 8/4 white ash stock specifically for making legs. But as soon as I saw the board, I knew there was no way I could use a film finish. The 8/4 board had several knots, waney edges, and a slightly grayish hue to it that obscured the grain. What happened is that I got a board that was cut very close to the heart, or it had an ingrown branch near the center.
My only option is to paint them. Oil-based paint is fine, but there's nothing exciting about it. So I turned my eye to milk paint.
Milk paint, so called because it uses slaked lime to bind to the milk protein casein, is a great water-soluble paint that leaves a thin, matte streaked finish to a piece. It doesn't completely obscure the grain, and the paint texture isn't exactly smooth, but the real clincher is that it mimics the look of painted antique furniture that you've seen, more than likely because those antique pieces were painted with milk paint. The grainy, streaked surface provides enough visual variation to give the piece character, and the tactile feedback from stroking it reminds you that you're touching wood and not plaster.
I've been using milk paint for almost a year and my enjoyment has increased with every use. Milk paint comes in powdered form. I use an 8 oz mason jar and mix equal parts water and powder and shake it as Mike Dunbar described in his thorough article in Fine Woodworking magazine. I sand between coats and stop at three. After it's dried for a few days, I'll rub a paper bag over it to dislodge any caked paint and to smooth out the surface just a little. You're left with a thin paint that will develop a nice patina with wear and time.
The positives:
  1. Texture
  2. Color
  3. Paint coats won't chip easily, they'll wear instead
  4. No Volatile Organic Compounds, unlike oil based paint, so you can paint to your heart's content, even indoors, while retaining most of your brain cells
  5. Looking at Mr. Dunbar's chairs, you can layer different color coats to mimic patina
  6. Cleaning paint brushes only requires dish detergent and warm water
The negatives:
  1. Not exceptionally convenient. If you mix the paint by stirring, you'll need to strain the clumps of undissolved paint from the jar. If you mix by shaking, you need to wait at least an hour for the froth to settle down
  2. The lime in the paint can burn your skin. I've never had this issue, only a mild itchiness, but if you're of the persuasion that flings paint everywhere, I'd wear a face mask so you don't burn your eyes
  3. It doesn't bind well over other types of paint. You'll need to strip or scrape away the old paint to bare wood prior to repainting
  4. Difficult to strip. The only solvent that can strip milk paint is lye which is extremely caustic

You can see what all the hoopla's about, in addition to the colors, here and here. I'm very partial to blues and reds.
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