Aluminum coatings minimum 1.8 mm thick are applied to water-cooled proton beam collimators used in the manufacture of medical isotopes on the TRIUMF TR30 cyclotrons in Vancouver, British Columbia, Canada. The sprayed surface of the collimators is made from silver. These collimators are used to trim the proton beam so that only a designated area on the isotope production target is irradiated with protons. Aluminum is used because its activation products at the energies used have short half-lives, thus minimizing the amount of collateral radioactivity produced. The aluminum is sprayed using an Axial III plasma spray torch. In service, the collimators are subject to high heat fluxes due to the proton beam. Service life, heat transfer and application data are provided in this paper.