Tips for Reducing Paint Use
As with most products, reducing the amount of paint purchased creates the least waste and has the greatest benefit to the environment.
Before you begin a painting project, measure the area first. Calculate the area to be painted (height x width = total area). One gallon (4.5 litres) covers about 400 square feet (37 square metres). There are paint calculators available on the internet. For example, Canadian Tire has an excellent calculator which allows you to calculate the amount of paint needed after you allow for windows and doors and paint surfaces.
Choose latex paint over alkyd (oil). It has reduced toxicity, and is easier to work with because it is water based. Look for the EcoLogo symbol for paints with lower toxic elements. Another possibility is recycled paint or low-VOC paint.
For jobs where the exact colour isn't important, ask your paint store about mistints. These are new paints that were ordered but weren't the right colour. Not only will you be using up good paint that might otherwise need disposal, but you will be saving money too. Mistints are typically cheaper than regular paint. SARCAN depots also have used paint to give away.
To prevent paint from drying out, cover the paint can (use its original container) with plastic wrap, replace the lid securely and store upside down. Protect your latex paint from freezing.
If you do have paint left at the end of a project, apply another coat to an area which could use extra protection. You can also use leftover paint for touch-up jobs, smaller projects or as a primer. Give away leftover paint to neighbours and friends. Cities with graffiti control programs can often make use of leftover paint, as can non-profit organizations.