Dear Recyclebank,

If high heat disposes of paper labels during the recycling process, why is a little pizza grease or food residue a no-no?

-Gerald B.

Dear Gerald,

Last week, we explained that, for the most part, you don’t have to remove labels from containers before tossing them into the recycling bin. The heat applied during the glass, metal, and plastic recycling processes removes labels and their adhesives, plus other contaminants like food residue. However, there are still a few reasons why grease and food residue should be strictly kept out of the bin.

1. While food residue gets burned away during the recycling process for plastic, glass, and metal, the same can’t be said for paper. When paper is recycled, it is mixed with water to form slurry. Oil and fat from food residue don’t mix with water; instead, they float on top of the slurry and mingle with the paper pulp. Oily pulp makes very poor quality paper and is, in effect, unusable. Paper products with grease or food residue, such as pizza boxes, should not be put in the recycling bin. Instead, compost it or just throw it in the trash.
2. In single-stream recycling communities, all accepted materials go in the same recycling bin together. This creates the risk of grease or food residue transferring from a plastic, metal, or glass container (which is technically fine to recycle even if it has residue on it) to paper materials (which cannot be recycled if it has residue on it). It’s best to avoid any possible cross-contamination by rinsing soiled recyclables and keeping all food residues out of the bin.
3. The biggest reason to keep grease and food residue out of the recycling technically isn’t a recycling issue at all! It’s a sanitary one. Food residue spoils, which can create unsafe conditions for workers in recycling facilities. Prevent mold and bacteria from growing on your recyclables by rinsing them before you put them in the bin.