The two plastics have different sensitivities. The butter tub melts into a watery substance whereas the milk jug melts into a more moldable viscous mass. So if there two versions of HDPE plastic are mixed together, bad things — as in gooey messes — start to happen at the reclamation plant.

“It’s like pancake mix and biscuit mix, they’re both made out of the same ingredients but it’s got a different blend of those components,” says Tamsin Ettefagh, an APR board member and vice president of Envision Plastics, the second largest recycler of #2 plastics in North Amereclyclablefoodcontainers_6970.jpgrica.

Think consumers aren’t confused? Ettefagh says she’s seen garden hoses, plastic lawn furniture and Halloween masks appear at her plant, given by eager beaver recyclers sending what they perceive as “plastics” to the great recycling beyond.

If this undesirable plastic isn’t sorted out ahead of time (fortunately, recyclers can handle a small percentage of nonconforming items), it contaminates the recyclable plastic, affecting its ability to be reinvented as carpet, fleece jackets, food containers, strapping, shampoo bottles, floor tiles and the host of other products made from reclaimed plastic.

What’s a conscientious consumer to do? The first step, says Cornell, is to get past “the general belief that all plastics are the same” and recognize that “errant plastics contaminate targeted plastics.”