Natural Whitewash is the First Finish at CGH

One of the most important features of Canada’s Greenest Home will be the use of nothing but non-toxic finishes for every surface in the home. Many of these will be home-made from natural ingredients. These non-toxic finishes will go a long way in ensuring that the home has a high level of indoor air quality, rather than the polluted air of most conventional new homes.

Natural finishes are an exciting part of this project because they are the most easily reproducible sustainable building element that a homeowner can apply to any new housing or renovation project. We hope the ideas and recipes we’ll post here will encourage more people to use natural finishes.

The whitewash we have used on the pine ceilings on the main floor of this home are a great example of a natural finish that is simple to make, non-toxic, durable and beautiful. Whitewashes have been used for centuries on wood and masonry surfaces, and bring a clean brightness to a room without affecting the moisture storage capability of the material or introducing any VOCs or petrochemicals to the building.

 

The whitewash recipe we used to achieve a semi-opaque whitewash on bare pine wood is:

1 part Casein powder
12 parts water
16 parts powdered hydrated lime

The water and casein were mixed 2-12 hours in advance and allowed to sit. The lime powder is then slowly added while stirring in a bucket with a drill mixer. The mixture will have some tendency to settle, and should be stirred frequently during application to ensure an even opacity. 1 gallon covers approximately 500-750 square feet per coat. We apply two coats to ensure an even coloration.

The amount of water can be varied to make a thinner or thicker paint, and pigment can be added to give tints. Without pigment, the colour is a bright white.

If powdered casein can’t be obtained easily, a similar recipe that will give good results can be made by mixing:

1 cup skim milk
90-120 grams of powdered hydrated lime

A good quality whitewash brush or thick paint brush with natural bristles will do the best job for applying this paint. On flat surfaces a roller could be used, but our V-groove ceiling required a brush to get into all the grooves.

This paint works so well because the casein molecule contains a powerful glue that is released when it reacts with the base nature of the lime, cracking open the casein molecule and allowing the glue to become a binder that securely bonds to the wood and the lime.

More natural finishes will follow!…

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