you get rid of the leftover paint, see if you can use it up in other projects
around the house, or ask your friends or neighbors if they could make use of
paint waste (paints, lacquers, thinners, white spirit used for cleaning the
tools) is hazardous waste.
paint waste must not be poured down drains or on to the ground, or placed in
the trash. Improper disposal of hazardous waste is harmful to the environment.
waste should be taken to a municipal hazardous waste collection point, for
larger cities, hazardous waste can be taken to a traveling collection
truck on regularly scheduled collection days a few times a year. Hazardous
waste can also accepted by some larger service stations and retail outlets. Each country adheres to the local
practices and legislation.
paint waste can be disposed of with mixed waste. Small amounts of liquid paint
can be left to air-dry in the can by leaving the lid slightly open.
you're not sure the paint is completely dried out, take the can to a hazardous
waste collection point.