October, 2007
Painting on walls is arguably humanity’s longest running DIY task. For most of our 30,000 years on the job we took scant regard to the risks to our health and environment, but these days only a caveman would ignore them.
What’s the problem? Aside from watching out for remnants of old lead based paints when renovating, you should be aware that Volatile Organic Compounds (VOCs) including benzene, formaldehyde, toluene, and xylene are used as solvents in some modern paints to make them flow properly, and in most paint strippers. These give off potentially harmful gases into the atmosphere during production and at room temperature – your room temperature. They can continue to do so long after they are dry.
So? VOCs do occur naturally. But you should take the headache, dizziness and sore throat from painting all day with the windows closed as a timely warning: scientific studies suggest increased exposure to VOC’s may cause effects which will mean more than a couple of paracetamol and a lie down.
The risks include possible damage to the liver, kidney, and your central nervous system as well as an increase risk of asthma.Some organics can cause cancer in animals; some are suspected of causing cancer in humans, and their release may also contribute to climate change. And if you don’t check, it may be that VOCs aren’t the only nasties lurking in your paint pot. Other potentially toxic substances in there include heavy metals, formaldehyde, ammonia, acetone, odour masking agents and the proven carcinogen, benzene.
Want paint without the pong? Water-based paints, sometimes referred to as latex paints, have become the norm across New Zealand’s $250 million decorative paint industry, making up about 75% of the most popular lines.They have a lower VOC content than solvent-based paints, and brushes, rollers etc used with them can be cleaned with ordinary soap and water rather than white spirit.
What’s the downside? Water-based paint must be protected from freezing and applied at a minimum temperature of 10 degrees Celsius. It can also rust steel and adversely affect some aluminium surfaces. It may have lower chemical and solvent resistance and reduced temperature resistance, meaning the paint may give a finish which is not quite as tough as its more toxic alternative. Its sensitivity to humidity also means that low humidity can cause it to dry extremely fast and even crack, while high humidity can cause very slow drying times.
The levels of VOCs vary in paints depending on their ingredients and the finish they are designed to produce. The tendency is for glossier finishes to require higher levels of VOCs. As a guide, UK-based DIY giant B&Q has developed its own company-wide labelling system, which defines VOC levels as:
- Minimal: 0 – 0.29%
- Low: 0.30 – 7.99%
- Medium: 8 – 24.99%
- High: 25 – 50%
- Very high: more than 50%
B&Q stipulates that the the term ‘VOC’ in the labelling phrases used must relate to the total VOC content of the product, and they use the term ‘minimal’ rather than ‘No-VOC’ or ‘VOC free’, otherwise VOCs can be present in the tints of paints marketed as having no VOC in their solvent.
Always read the label. The VOC content may also be expressed as grams/litre (g/litre). To convert this into a percentage on the B&Q scale, divide by 10. Look out for paints with the Environmental Choice NZ stamp. Including their tint they are between 5-10% VOCs, depending on the finish, which would put them in B&Q’s low and medium categories. These also comply with additional standards on heavy metals, packaging, consumer information, product stewardship, waste and energy management. But you may need to ask the manufacturer to be sure, since no standard compulsory VOC labelling system exists.
If you want really green biodegradable paint in virtually any colour. You can go for paints made from blends of plant oils, tree resins and earth clays. The ingredients list for these tend to read more like a half decent fruit cake than a hardwearing substance you spread on your wall. It is best to ask the retailer which one to use for areas which need regular washing or a particularly tough finish. Given proper maintenance, they should last as long as the more toxic paints and come complete with highly valuable peace of mind.
And if you don’t think that is the way of the future for paint, what about this? Oxford University scientists have been researching the possibilities of using single cell algae to make eco-friendly iridescent paints that shimmer into different colours as you move around the room. Each tiny organism has a silica shell with tiny holes that only allow some colours of light through. The plan is to use a low energy process to grow huge amounts of the algae, and then kill them off with heat or mild acid to leave the shells for use in the paints.
Paint instead of heating? Insulating and thermochromic paints, which change colour with differing temperatures, may become an integral part of a home’s internal atmosphere control system. In 2001 at Tongji University in Shanghai scientists began developing paints able to reflect heat when the weather is hot, to keep your house cool, and absorb heat in cold periods to help keep you warm inside. It also changes colour to match the seasons. But the challenge will remain to produce these products in ways which don’t help make our seasons even more erratic, or place our long-term health at risk.