Use of only a single layer of plastic to cover silage piles can lead to substantial surface spoilage of silage (i.e., increased pH and temperature, discoloration, molding). The extent of spoilage losses can be curtailed if a thin plastic underlay film is utilized under the outer white/black plastic cover. Our objective was to determine if a clear plastic polyethylene film (Poly) has an impact on the nutritional quality of the outer 50 cm layer of corn silage vs. an oxygen barrier (OB) film when used as an underlay. Two wedge type corn silage piles with east/west, and 2 with north/south, orientation were constructed in fall 2014. Each pile was alternately covered with a clear, pliable polyethylene film of 1.6 mil HiTec Underlay (ARI, Belmont, CA) or an OB plastic film of 1.8 mil from Industria Plastica, Mongralese, Italy (trade name ‘Silostop’) with a 1.8 m overlap between sections and then covered with a conventional plastic cover. After 90 d, all piles were sampled to a 50 cm depth with a silage probe, divided into 2 samples of 25 cm (i.e., 0–25, 25–50 cm depth) each at 4 sample points in each of the 4 sections. Temperatures and pH were determined at core extraction. Each core sample was preserved individually (n = 32) for mold and yeast counts and part was pooled by section location (upper vs. lower; n = 16) and analyzed for volatile fatty acids, lactic acid and ethanol. There were no differences between the silages under the Poly and OB films in temperature (24.7 vs. 24.2 for N/S and 23.1 vs. 22.4°C for E/W piles), pH (3.79 vs. 3.84 for N/S and 3.77 vs. 3.84 for E/W piles) or mold and yeast counts, which were all below 0.5 million cfu/g. Volatile fatty acids were similar between treatments, with lactic, acetic and propionic acid averaging 2.93 and 3.57, 1.73 and 1.93, 0.38 and 0.24% DM for N/S and E/W piles respectively, with none being statistically different. Butyric acid occurred at a very low level, 0.05% DM, and ethanol was 0.53% DM, with no differences. Overall, it was judged that there were no differences in the silage quality of the outer 50 cm layer of corn silage after ~90 d of ensiling when covered with a clear polyethylene film vs. an oxygen barrier film under the outer black/white plastic cover.