Neon (霓虹) is to Hong Kong as red phone booths are to London and fog is to San Francisco . When night falls , red and blue and other colors __1__ a hazy (雾蒙蒙的) glow over a city lit up by tens of thousands of neon signs . But many of them are going dark , __2__ by more practical , but less romantic , LEDs (发光二极管). Changing building codes , evolving tastes , and the high cost of maintaining those wonderful old signs have businesses embracing LEDs , which are energy __3__ , but still carry great cost . " To me , neon represents memories of the past ," says photographer Sharon Blance , whose series Hong Kong Neon celebrates the city's famous signs . " Looking at the signs now I get a feeling of amazement , mixed with sadness ." Building a neon sign is an art practiced by __4__ trained on the job to mold glass tubes into __5__ shapes and letters . They fill these tubes with gases that glow when __6__ . Neon makes orange , while other gases make yellow or blue . It takes many hours to craft a single sign . Blance spent a week in Hong Kong and __7__ more than 60 signs ; 22 of them appear in the series that capture the signs lighting up lonely streets — an __8__ that makes it easy to admire their colors and craftsmanship . " I love the beautiful , handcrafted , old - fashioned __9__ of neon ," says Blance . The signs do nothing more than __10__ a restaurant , theater , or other business , but do so in the most striking way possible .