A masking film has a unique polymeric binder in the imageable layer that enables the imaged film to be readily solubilized in non-chlorinated developers when it is used to form a relief image in a radiation-sensitive element, such as a UV-sensitive flexographic printing plate precursor. The polymeric binders in the imageable layer are resins that can be dissolved or dispersed in cyclohexane at 10% solids at 23°C within 24 hours.