Debate over the corona's finish continued into 2014 before being resolved. The Commission of Fine Arts repeatedly urged the architects to use bronze for the scrim, as it created a "shimmering, lustrous effect under many lighting conditions" and "conveyed dignity, permanence and beauty". Duranar paint was the first substitute proposed by the architects, but the commission members rejected it, noting that it had a "putty-like appearance under overcast conditions" and visually fell "far short of the beautiful poetic intention promised by the concept design". A second finish, the sprayable metal LuminOre, was rejected by the commission because it was difficult to produce in the high quality needed, and was prone to flaking and discoloration. Electroless plating and anodized aluminum were rejected because they lacked durability. A physical vapor deposition process involving a nickel-chrome plating was dismissed for not achieving the right color, luster, or warmth. In early 2014, tests were made with polyvinyl difluoride (PVDF). This coating was approved by the Commission of Fine Arts on February 20, 2014, and by the National Capital Planning Commission in April 2014.