If you've ever tipped a black plastic meat tray or ready-meal container into your yellow bin and wondered whether it actually gets recycled, the honest answer is: probably not. Black plastic is one of the trickiest materials in the household waste stream, and understanding why can help you make better choices at the supermarket and the bin. It's a small thing, but multiplied across millions of trays a year, it adds up to a real problem for New Zealand's recycling system.

The issue comes down to how recycling facilities sort plastics. Modern material recovery facilities use optical scanners that fire near-infrared light at each item and read the light bounced back to identify the type of plastic. Black plastic gets its colour from carbon black pigment, which absorbs that infrared light rather than reflecting it. The scanner effectively sees nothing at all, so the tray isn't identified, isn't sorted into a plastic stream, and ends up being pulled out as a contaminant and sent to landfill. The plastic itself may well be a recyclable type like PET or polypropylene, but if the machine can't see it, it can't sort it.

Colour isn't the only hurdle. Many black trays are made from mixed or multi-layer plastics, or come with a film lid and an absorbent pad that all have to be separated. Trays contaminated with meat juices, fat or food residue are also more likely to be rejected. Even where a tray carries a resin code (the number in the triangle), that symbol only tells you what the plastic is made of — it is not a guarantee that your local facility can actually accept and process it.

Under New Zealand's standardised kerbside rules, the yellow bin accepts plastics numbered 1, 2 and 5 in the form of bottles, trays and containers. However, black plastic remains problematic regardless of its number because of the sorting issue, and some councils specifically ask you to leave black trays out. Because acceptance still varies from place to place, the safest move is to check your local council's website or bin guide rather than assuming. When in doubt, keep it out — a rejected item can contaminate an otherwise good load.

The most effective thing you can do is reduce black plastic before it reaches your bin. Choose loose fruit and vegetables over pre-packed trays, buy meat from a butcher's counter in paper where you can, and favour clear or lighter-coloured packaging that scanners can actually read. Some brands are switching to detectable or non-black trays precisely because of this problem, so your buying choices send a signal. Rinse and recycle the packaging you can, and if a black tray genuinely can't go in your yellow bin, put it in the red general-waste bin rather than wish-cycling it.

The practical takeaway is simple: don't be fooled by the recycling triangle on a black tray. In most of the country it will slip through the sorting process and head to landfill, so reducing what you buy is far more powerful than hoping it gets recycled. Check your council's guidelines, choose lighter packaging when you shop, and keep questionable items out of the yellow bin to protect the quality of everyone's recycling.