Paper towel rolls, the inner cardboard tubes, are generally compostable. This practice repurposes a common household item and adds valuable material to a compost system. Made primarily of wood pulp fibers, the tubes are an excellent source of carbon for the decomposition process. Composting them is a straightforward way to reduce household waste. The following details how to prepare the rolls and what potential contaminants to avoid for a successful compost batch.
Understanding the Material and Its Role
The paper towel roll is composed mainly of cellulose, a complex carbohydrate that forms plant cell walls. This cellulose-rich material is classified as a “brown” component in composting terminology. Brown materials are dry, slow to decompose, and provide the necessary carbon (C) source for decomposition microbes.
Microorganisms require a balanced diet of carbon and nitrogen (N) to efficiently break down organic matter. The ideal carbon-to-nitrogen ratio for an effective composting environment is around 30:1 by weight. Since kitchen scraps and grass clippings are high in nitrogen (greens), adding paper towel rolls helps balance this ratio by supplying carbon. Sufficient carbon prevents nitrogen from releasing as ammonia gas, which can lead to unpleasant odors and a loss of nutrients from the pile.
Preparing Paper Towel Rolls for Composting
The rigid, cylindrical shape of a whole paper towel roll can slow down its decomposition. For efficient breakdown, the cardboard fibers must be exposed to moisture and microbial action. Simply tearing or cutting the rolls into smaller pieces is the most important preparatory step.
Shredding or tearing the cardboard significantly increases the surface area available for bacteria and fungi to metabolize the cellulose. Aim for pieces no more than a few inches in size to encourage rapid breakdown. Since cardboard is highly absorbent, it can be soaked in water before being added. This wetting action ensures the material is saturated, helping to maintain the overall moisture level of the compost and accelerating the initial decomposition phase.
Identifying and Avoiding Contaminants
While the cardboard itself is compostable, paper towel rolls can contain non-compostable elements or residues that must be avoided. The glues used to hold the cardboard layers are generally starch-based and safe to compost. However, any non-paper tape, stickers, or excessive glue residue should be removed before composting, as these often contain plastics that will not break down.
Inks and dyes are a concern; while most modern black inks are vegetable-based and safe, glossy finishes or heavy color printing may contain heavy metals. Avoid composting rolls that have a noticeable sheen or significant colored graphics. Furthermore, the roll may have absorbed residues from the paper towel, such as cleaning chemicals, grease, or oil. If a roll is heavily stained or exposed to hazardous substances, it should be discarded to ensure the final product remains clean and safe.