What's the price impact of contaminated cardboard, like boxes with grease or food residue?
Short answer: Grease and food-contaminated cardboard is typically discounted heavily or rejected outright, because contaminated fiber can't be repulped into new paper products the same way clean cardboard can — pizza boxes and produce boxes with wax coating are common examples buyers specifically watch for.
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List Free →Why grease is a dealbreaker for recycling
Paper recycling works by breaking cardboard down into pulp fiber, and grease or oil contamination interferes with that process, weakening the resulting fiber and sometimes making a batch unusable for the mill. This is different from most metal contamination, which just reduces yield — grease contamination can make paper genuinely non-recyclable.
What buyers actually check for
Common red flags include pizza boxes with grease-soaked bottoms, food takeout containers, and produce boxes that have been in contact with wet or greasy produce. Even a relatively small proportion of contaminated boxes mixed into an otherwise clean bale can trigger a rejection or steep discount if a buyer can’t easily sort it out.
What you can do
Sorting out visibly greasy or food-stained cardboard before baling, even roughly, protects the value of the rest of your clean cardboard — mills would rather see a smaller clean load than a larger load they have to inspect piece by piece.
How ScrapTrade Makes This Easier
Noting “clean, no food contamination” versus general mixed cardboard in a ScrapTrade listing helps buyers trust the load enough to offer a clean-grade price, rather than pricing defensively for contamination they can’t see in photos.
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