Recycling by product massive number of types of plastic, they each carry a resin identification code, and must be sorted before they can be recycled. This can be costly; while metals can be sorted using electromagnets, no such 'easy sorting' capability exists for plastics. In addition to this, while labels do not need to be removed from bottles for recycling, lids are often made from a different kind of non-recyclable plastic. To help in identifying the materials in various plastic items, resin identification code numbers 1-6 have been assigned to six common kinds of recyclable plastic resins, with the number 7 indicating any
Recycling symbol the following recycling symbols: An ISO/IEC working group has researched and documented some of the variations of the recycling logo currently in use, and has made recommendations for adding some more of them to the Unicode standard. With the rapid expansion of materials converted to printer filament for 3-D printing using recyclebot technology, a large expansion of resin identification codes has been proposed. In 1988, the American Society of the Plastics Industry (SPI) developed the resin identification code which is used to indicate the predominant plastic material used in the manufacture of the product or packaging. Their purpose is to