PPG Industries' optical and specialty materials division achieved an 8 percent increase in sales to $334 million for the first quarter of 2012. The segment's operating margin grew to 32.6 percent from 29.2 percent one year ago, mainly due to higher volumes of optical products resulting from further market penetration, despite modest inventory restocking by customers. Currency remains a negative factor, however. PPG's total sales reached $3,752 million in the quarter, up from $3,533 million in the year-ago period, including a contribution of $133 million from higher prices for coatings. Adjusted net income increased to $279 million from $228 million.