In 1943, Urey brought in Hugh S. Taylor from Princeton University to look at the problem of a usable barrier. Libby made progress on understanding the chemistry of uranium hexafluoride, leading to ideas on how to prevent corrosion and plugging. Chemical researchers at the SAM Laboratories studied fluorocarbons, which resisted corrosion, and could be used as lubricants and coolants in the gaseous diffusion plant. Despite this progress, the K-25 Project was in serious trouble without a suitable barrier, and by August 1943 it was facing cancellation. On 13 August Groves informed the Military Policy Committee, the senior committee that steered the Manhattan Project, that gaseous diffusion enrichment in excess of fifty percent was probably infeasible, and the gaseous diffusion plant would be limited to producing product with a lower enrichment which could be fed into the calutrons of the Y-12 electromagnetic plant. Urey therefore began preparations to mass-produce the Norris-Adler barrier, despite its problems.