Firstly, remember to calculate how much paint you need before starting the job (see "How much paint/varnish do I need?") This should eliminate the need to dispose of large quantities of paint or varnish.
Do not pour leftover paint or varnish in to drains or watercourses. Remove excess material from brushes and rollers by wiping off onto newspaper or rag and spread out to dry before disposal. Use an inert, absorbent material (such as cat litter) to soak up small amounts of water based coatings – then dispose of in a dustbin. For larger amounts ask your local authority for guidance. Some local authorities have separate facilities for coatings and recycling of empty or dried out cans as many do not want coating waste in the dustbin.
Remember that when disposed of as waste, paints and varnishes can create problems for landfill sites if not mixed in with other rubbish and due to their messy nature, they can contaminate recycling schemes.
If leftover product is stored carefully it can often be re-used. Keep the lid firmly on the can to ensure a good seal. Protect water based coatings from freezing and all coatings from temperatures above 35°C.
Consider donating any leftover material to friends, family, local charity group or community repaint scheme. See the Save Waste and Prosper Website www.communityrepaint.org.uk (in Scotland www.repaintscotland.com ) for further information.