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T&D > Programs Areas > Inventory & Monitoring > String Degradability Program Areas
String & Flagging Degradability
Andy Horcher, Project Leader


There is growing concern over the materials left behind in the course of conducting field work. In the case of hip chain line, or string-box string, this material can be detrimental to the health of fish and wildlife, where entanglement can result in injury or death. Unfortunately the degradability of these materials is unknown, making it difficult to accurately weigh one product against another. The goal of this project is to compile information on the degradability of hip chain line and flagging tape and provide hip chain alternatives for making distance measurements.

Proposed by Elaine Rybak and Richard Toupin, of Region 6, this project was modified and approved by the Inventory and Monitoring Steering Committee.

Using a weather acceleration method, we investigated the relative degradability of various types of sting-box string, or hip chain line, and flagging. The samples were tested in new condition, after 126 hours of accelerated weathering, and after 500 hours of accelerated weathering. The results of these tests are shown below. Samples with no results for the 500 hour test were degraded beyond measurable strength, where the samples crumbled when moved from the test chamber; in these instances breaking strength was recorded as zero.

Click here for the Flagging Breaking Strength with Accelerated Weathering graph.

Bar chart displaying the breaking strength of four types of hip chain.
Click on image for larger view.

This weather acceleration cannot be directly correlated to actual outdoor degradation without conducting outdoor testing. Therefore outdoor are conducted for comparison. Shade cloth is used to mimic forest canopy cover. These results will be posted as they become available.