Mastication is a wildland fuel treatment technique that is rapidly becoming the preferred method for many fire hazard reduction projects, especially in areas where reducing fuels with prescribed fire is particularly challenging. Mastication is the process of mechanically modifying the live and dead surface and canopy biomass by chopping and shredding vegetation to reduce canopy bulk density, raise canopy base height, lower surface fuelbed depth, and increase surface fuelbed bulk density, thereby reducing fire hazard. However, little is known about the properties of masticated fuelbeds as they age. In 2013, we began a comprehensive study called MASTIDON (MASTIcated fuelbed Decomposition Operational Network) to measure the diverse characteristics of masticated fuelbeds at treatment sites of different ages across the western U.S. Rocky Mountains. Our primary objective was to evaluate effects of aging of masticated fuelbeds on fire behavior, fuel moisture dynamics, soil heating, and smoldering combustion. Results from these investigations could then be used to build fire behavior fuel models for use in operational fire management. This report concerns a small facet of the MASTIDON study, where summaries of the physical and chemical fuel properties of the sampled masticated fuelbeds are presented and the relationships of these properties to fuel age are explored. We document masticated fuelbed characteristics and correlate these characteristics to age. In general, we found that there were few changes in physical and chemical properties over the short 10 years represented by the sites in this study, primarily due to confounding factors of low decomposition rates, diverse mastication techniques, wide range of biophysical conditions, and high variability in fuel properties across disparate sites. However, we feel it will take more than 10 years for decomposition to mitigate the negative impacts of wildfires burning in masticated fuelbeds. These summaries can be used to understand how different types of masticated fuelbeds might burn if ignited and as inputs to fire behavior and effects models.