DIY Clay-Based Paints

Many of today’s paints are made from unhealthy, synthetic materials that contribute to poor indoor air quality and poor health. While many no- or low-VOC paints are now available, many are still made with materials from destructive industrial processes. They may not have VOCs but that’s not to say they’re benign. Luckily, you can make your very own paints using clay. Clay-based paints are not only non-toxic, but also life-enhancing, not to mention beautiful!

The amazing thing about clay paints is that they go beautifully over natural materials but you can also use them to rehabilitate a conventional surface, like painted drywall. And best of all, you can make clay paints for just a few dollars per litre.

To begin you’ll have to make 2 coats – a base coat and a top coat. Here’s what you’ll need to do:

Base coat

Starter recipe:

–  1 part clay subsoil, coloured clay or bagged clay (kaolin clay) – available at any pottery supply store

–  1 part fine sand (silica, 125 grit or finer)

–  ½ part wheat flour paste (see recipe below)

–  pigment optional (not entirely necessary in the base coat)

Mixing:

  1. Make up wheat flour paste and allow to cool
  2. Add roughly 2-3 parts cold water to every 1 part flour paste to make liquid enough to incorporate into the remaining ingredients
  3. Add sand and clay to wheat flour paste and whisk together until the consistency of a heavy cream.

Top Coat

Starter recipe:

–  Same as the base coat, though you may choose to add mica or finely chopped straw (chop in a bucket with a weed whacker, blender or use scissors) at this point to give more texture. 

–  For colour, add mineral-based pigment. These are available as iron oxides from pottery supply stores (avoid heavy metal-based pigments, also available at pottery stores) or from American Clay or Solamente Color, both of which are supplied through Riva’s – The Eco Store in Calgary, AB.

Mixing:

–  Same as for the base coat.

–  Add colour pigment into this mix. Start with 1 tsp per litre, adding more for more vibrant colours. This is where experimenting and making test patches is important (see test patch guidelines below).

Application

  1. Simply apply with a standard paintbrush, working it in all directions until you have full coverage.
  2. Let this layer fully dry before applying the top coat.
  3. Apply top coat just as you did the base coat but be sure not to overwork. Overworking this layer can dissolve the base layer, making the wall streaky.
  4. Allow the top coat to dry until leather hard (the point where it has dried sufficiently but is still damp and workable – this usually takes around 10 – 30 minutes). Use a damp sponge and work gently in a circular motion to remove brush strokes and to bring out straw fibres if added. 

Test Patch Guidelines

–  Paints should not dust off on your hands or clothes when dry. If they do, you’ve added too much sand, too little clay or too little wheat paste. Adjust accordingly.

–  The surface should be relatively smooth. Too much grit means you have too much sand.

–  If the paint cracks, there is too much clay, not enough sand, or it has been applied too thickly. Adjust accordingly.

Coverage

–  Approximately 6 – 7 m2 per litre.

Wheat flour paste recipe

  1. Whisk together 1 cup white flour and 2 cups cold water into a smooth paste, working out all lumps.
  2. Bring 6 cups of water to a rolling boil in a large pot.
  3. Maintaining the boil, add the wheat-water mixture, stirring constantly.
  4. Continue this until the paste becomes thick and slightly translucent. The paste is now ready and should be cooled before using. Use immediately otherwise it will mould.

Adapted from the book Using Natural Finishes by Adam Weismann & Katy Bryce.

 

 

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