Some materials can be recycled infinitely. Others only make it through the process once before heading to the dump. How a recyclable stands up to the violent forces that re-form it into raw material for manufacturing determines its longevity. If its basic properties don't change, it can be recycled almost without limit. Its recycling days are numbered, however, if it degrades, or downcycles, to a lower-quality material. (See References 1)
Metals like steel, aluminum and copper are recycling stalwarts. Their properties hold steady no matter how many times they are melted down (see References 2, 3, 4). Copper recycling has been common since it began in ancient times, and a large amount of all copper ever mined is probably still in use somewhere today (see References 4). Today's discarded aluminum soft drink cans transform into new cans in as little as 60 days (see References 2). Modern electric arc furnaces can melt steel scrap into new steel in less than an hour (see References 5).
Glass is also endlessly recyclable, as long it's the right kind and gets properly sorted. Old jars and bottles easily transform into new containers when they are separated into clear, brown and green glass. If different colors mix in a furnace the result can end up as trash instead of a new product. Window panes, some glassware and light bulbs, however, may not be recyclable at all --- they are created through more complicated manufacturing processes than simple jars and bottles and may contain substances that affect the purity of the glass. (See References 6)
Recycling paper involves multiple bouts of shredding, pounding, soaking and heating to turn it into the fibers needed for new paper. The fibers get a little shorter each time they go through that process. The shorter the fibers, the lower the quality of the new paper they can make. The fibers usually become too short for the lowest grade of paper after being recycled five to seven times, according to the U.S. Environmental Protection Agency. (See Resources 1)
Most plastics degrade during reprocessing and have only one successful recycling. Therefore, plastics from widely-collected products such as soft drink bottles and milk jugs often are downcycled into nonrecyclable items like fleece clothing and plastic lumber. (See Resources 2)
- Earth911: Truth About Glass Recycling; Trey Granger; June 22, 2009.
- The Aluminum Association: Recycle Aluminum Cans
- World Steel Association: About Steel
- International Copper Association: Copper Recycling
- Steel Works: Electric Arc Furnace Steelmaking; Jeremy A. T. Jones.
- Recycle Arizona: Recycling Plastic, Glass and Paper
- Thomas Northcut/Photodisc/Getty Images