Silk-screen ink comes in two types: plastisol or water-based. These inks allow vibrant printing on textiles and paper, and both contain environmentally unfriendly chemicals. Proper disposal of silk-screening ink varies by your location, the type of ink you have and municipal rules, which may change. Call your town each time you need to dispose of ink to ensure that the regulations are the same, and follow the proper protocol for lawful disposal.
Reuse leftover silk-screen ink to test prints, or combine small amounts of ink to make new colours. Use the leftover ink for non-critical applications like testing a new print, making a simple print or for personal use. Marci Kinter of the Printers' National Environment Assistance Center notes that you may end up with interesting colours this way, and reuse cuts down on the amount of ink you'll need to dispose of.
Check your ink container to determine whether it's water-based or plastisol. Water-based silk-screen inks have water as an ingredient; plastisol ones do not.
Call your municipal waste centre and tell them you have liquid plastisol ink or water-based screen print ink. Ask about proper disposal methods. Some communities accept liquid plastisol ink for disposal, while others mandate that you cure this ink by heating it to 160 degrees Celsius. One gallon of plastisol-based ink can be cured in one hour.
Throw out sealed containers of plastisol-based silk-screen ink that you have not been able to reuse, if your community allows this. If you need to cure the ink before doing so, heat it in a container of hot water, measuring the ink temperature with a thermometer to ensure that it stays hot enough.
Take water-based ink to the landfill or hazardous waste collection site in your community. This ink cannot be disposed of unless you evaporate out all the water, which home artisans cannot do. If plastisol ink is a hazardous waste in your community, also take these inks to the landfill or hazardous waste collection site.