The empty cardboard tube remaining after a roll of paper towels is finished is a common item many people look to divert from the landfill. This material, often called a paper towel roll, is essentially a type of clean, dry cardboard. As more households embrace composting, the question of whether this byproduct can join food scraps and yard trimmings is important. Understanding its basic composition and how it interacts with decomposition helps maximize the efficiency of a home compost pile.
The Composition and Compostability
The core material of the paper towel roll is unbleached or lightly bleached paperboard, which is composed primarily of cellulose fibers derived from wood pulp. This plant-based structure makes the roll inherently biodegradable and fully compostable. In composting, this cardboard is classified as a “brown” material because it is dry, relatively hard, and rich in carbon.
Carbon-rich materials are necessary to balance the “green” materials, which are nitrogen-rich, like fresh food scraps and grass clippings. Microorganisms in the compost pile require a specific carbon-to-nitrogen ratio, ideally around 30-to-1, to thrive and efficiently break down the waste. The carbon-heavy paper towel roll helps supply this necessary carbon, preventing the compost pile from becoming overly dense, wet, and anaerobic. Using these rolls supports the microbial activity that turns waste into nutrient-rich soil amendment.
Preparing the Rolls for the Compost Bin
While the rolls are compostable, their cylindrical shape and dense structure can slow down the breakdown process considerably if added whole. The most effective way to ensure rapid decomposition is to increase the material’s surface area. This is best achieved by tearing, cutting, or shredding the cardboard tube into small, flat pieces, ideally no larger than one or two square inches.
The dense cardboard tends to be very dry, which can impede the decomposition process by creating dry pockets within the pile. Before adding the pieces, they should be thoroughly wetted, though not soaked to a dripping point. Incorporating these moistened, shredded pieces directly into the center of the compost pile allows them to mix well with nitrogen-rich “green” materials. This helps maintain the proper moisture level and carbon-to-nitrogen balance needed for the heat-producing microbial activity to occur.
Important Exceptions to Consider
While plain paper towel rolls are a good addition, certain conditions or contaminants can make them unsuitable for home composting. Any roll with excessive amounts of non-biodegradable adhesive, such as packing tape or heavy glue residue, should be removed before composting. Similarly, rolls with glossy finishes or significant amounts of bright, non-soy-based ink or dye are best left out. These materials may contain heavy metals or chemicals that could inhibit microbial activity.
If the cardboard has been used to soak up non-biodegradable liquids, it should be discarded in the trash. This includes chemical cleaners, motor oil, paint, or excessive amounts of cooking grease and dairy products, which can attract pests and introduce harmful substances to the compost. Unlike commercial composting facilities, home composting systems are more sensitive, requiring clean, uncontaminated materials to safely produce a healthy soil amendment.