Diary Of An Eco-Builder

There's nothing like a wall finish to bring joy to the heart of a self-builder. I've grown so accustomed to the guts of Tree House hanging out all over the place that a perfectly plastered wall, courtesy of super-smooth Calvin, feels like an extravagant luxury. In fact, it's the cue for more hard labour - a long-anticipated paint job.

Whitewash, a traditional paint made with lime, is the etymological ancestor of greenwash, the corporate practice of dressing up a polluting business in a cloak of environmental respectability. This is irresponsible, but I think far greater harm is done by pinkwash: imbuing environmentally harmful products with such a fluffy aura that shoppers have no hesitation in snapping them up and foisting them on their new-born babes.

Paint is a pinkwashed product. Little Dorothea is due soon, so it's time to pop down to the DIY warehouse and wander among the gleaming tins, browsing the colour catalogues filled with cheerful homes and healthy families. Soon, mum and dad have 10 litres of Oxtongue Cerise for the nursery walls. Dad gets a headache painting the room, but the air soon clears and all that's left is the satisfying smell of freshly painted walls.

But you don't have to scratch much away to see what lies below. Synthetic paint is made from crude oil, cracked at high temperatures to produce a range of hydrocarbons that are then processed to make a fistful of chemical ingredients, leaving a volume of toxic waste behind many times greater than the paint produced. When the paint is applied, the solvents evaporate, becoming volatile organic compounds (VOCs) that are known to cause respiratory and neurological problems (water-based paints may be "low VOC" but they contain other chemicals that are far from benign). Two weeks later, the paint is still fresh enough to give Dorothea a good initiation into a lifetime of indoor air pollution.

Not surprisingly, synthetic paint makers don't advertise their ingredients, so if you want this information you will have to look elsewhere - to the natural paint suppliers. Natural paints, derived from plants, minerals and the odd insect (cochineal is made from crushed bugs), have an impressive track record. The remarkable paintings in the Grotte Chauvet in France are more than 30,000 years old, so you needn't worry about quality and durability.

The paints we are using in Tree House are made by Auro, a German company that only uses natural raw materials, all of which it is happy to declare (www.auro. co.uk). Although more expensive than a comparable pot of petrochemicals, there are no hidden environmental costs in manufacture and waste disposal. We can compost any paint left over. Some natural paints do emit VOCs from citrus-based solvents, but Auro wall paints are 100 per cent water-based, so we won't be getting high on paint fumes.

If you have the time and enthusiasm, you can make your own paint. It's amazing what you can do with milk and lime juice, the basis of casein paints - see The Natural Paint Book (Kyle Cathie, 2002). Bear in mind that natural paints are not identical to synthetic paints in use and application, so don't force them on an unsuspecting decorator. Get advice first from a good eco-merchant (www.greenshop. co.uk; www.constructionresources.com). So there will be no pinkwash, greenwash or whitewash in Tree House. But you must forgive me for the odd lapse into gingerwash - don't let anyone persuade you that cats are anything other than 100 per cent eco-friendly.

Will Anderson's complete 'Diary of an Eco-Builder' will be published by Green Books in spring 2006 ( www.treehouseclapham.org.uk)