Flashing (weatherproofing) bark was occasionally used as a flashing material. Most flashing materials today are metal, plastic, rubber, or impregnated paper. Metal flashing materials include lead, aluminium, copper, stainless steel, zinc alloy, other architectural metals or a metal with a coating such as galvanized steel, lead-coated copper, anodized aluminum, terne-coated copper, galvalume (aluminum-zinc alloy coated sheet steel), and metals similar to stone-coated metal roofing. Metal flashing should be provided with expansion joints on long runs to prevent deformation of the metal sheets due to expansion and contraction, and should not stain or be stained by adjacent materials or react chemically with them.
What Time Is It? (song) Efron) and Gabriella Montez (Vanessa Hudgens) is also visible. When the clock has ten seconds to go before the bell, the class commenced chanting "summer!" getting louder until the bell rings, after which the song is performed. The music video contains clips directly from the movie, and was released on July 31, 2007 on the iTunes Store. The music video was also released on the Disney Channel. The song peaked at number 1 on the "Billboard" Hot Single Sales chart for 28 weeks, which became the highest selling single of the year-end chart in 2007. What Time Is It? (song)