You might have noticed when doing your shopping that certain food items come in black plastic trays instead of clear ones. This makes the food stand out more, and it looks much more tasty! What you might not know though is that the black pigments added to the plastic are so good at absorbing light that they can interfere with infrared sorting systems used in recycling stations, kind of like a disguise. Carbon black pigments are most commonly used, and because the pigment stops the sorting machine from detecting the plastic type, plastics with them are often sent to land fill instead of being recycled.
In the UK, some supermarkets are trying to address the issue by phasing out black plastics in their own-brand packaging, while others are developing new black pigments that can be sorted by infrared. But in the mean time, maybe we should all consider buying food in slightly less attractive packaging, (or even better, avoid food in plastic packaging completely!)
http://www.wrap.org.uk/content/recyclability-black-plastic-packaging-0
the Runaway Lab Book 