What happens to all those 3-D glasses after they’ve been used to goggle?
They usually get washed or recycled. There are a number of manufacturers battling for control of the 3-D market. Most of these companies make reusable glasses, though the market leader, RealD, primarily makes single-use spectacles. (RealD has also launched a line of reusable designer glasses.)
Reusable glasses are generally collected in trays and then cleaned in a dishwasherlike machine (or, in some cases, in an actual dishwasher). IMAX Corporation has its own, proprietary washers that exhibitors are required to use on-site. Dolby Laboratories demands that theaters use a commercial-grade dishwasher. XpanD Cinema says that most of their exhibitors use commercial dishwashers, too, but that any kind of dishwasher and detergent is fine as long as temperature is kept below 140 degrees and you use a nonammonia cleanser. (Otherwise, you could damage the lenses’ liquid-crystal display or discolor the plastic.) XpanD also says that some of its exhibitors, like the Cinerama Dome in Hollywood, have a staff member hand-clean each pair with a cloth and some light soap, whereas others choose not to clean the glasses at all—instead, they hand out individual disinfecting wipes to each customer.