Water based vs Solvent based
Generally, consumers can choose between two types of paints:
- Water-based paints
- Solvent-based paints
As their name indicates, solvent-based paints, sometimes referred to as "oil-based" or "alkyd" paints, contain a significantly higher level of organic solvents than water-based paints. These solvents are responsible for the strong odor noticeable in buildings that have been freshly painted. They are also potentially hazardous for both human health and for the environment which is why concerted efforts are being made to reduce or remove their presence in paints without negatively impacting on paint performance.
Today, water-based paints dominate and account for roughly 80% of paints sold in the residential market.
A simple way of finding out if a paint is water-based or solvent-based is to check on the label about how to clean brushes. Solvent-based paints need to be cleaned with white spirit or turpentine, water-based paints can be cleaned with warm, soapy water.
The function of organic solvents in a paint relates to certain properties it brings – it facilitates the paint’s application, it’s drying, and the formation of a regular paint film. During application and drying, the solvent evaporates. Ideally a dry paint film no longer contains solvent. However when they evaporate, these solvents release Volatile Organic Compounds (VOCs) into the atmosphere, with a negative, toxic impact on the environment.
Fifty years ago, virtually all paint was solvent-based. Today, advances in paint technology mean that modern, water-based paints, often referred to as acrylic emulsions, are increasingly replacing organic solvents across a broad range of paint applications and surface areas (and account for 80% of architectural paints). Legislation is in place to support this trend.
Spear headed by (but not limited to) to regulatory developments in California, we continue to see stricter paint VOC regulations across the US and Canada. In terms of total VOC’s, 100 g/l paints are very common today. And predictions are that most manufacturers will have 50 g/l in the near future.
From a performance standpoint, advances in paint technology mean that high quality water-based paints are in many respects equal to or superior to their solvent-based equivalents. High quality acrylic emulsions offer excellent durability, quick drying time, and the emission of less odor.