Indoor Gardening and Houseplants: how do you clean greenhouse dust and dirt off your plants?, 1 by Sofonisba

Sofonisba wrote:
Just got this yucca today at Home Depot. They made me wait 15 minutes while they wandered around looking for a sku on it. Turns out, it was only $2 and some change.

Anyway, its leaves are covered with a white sediment... or something. I don't know what it is. I tried cleaning each leaf off by hand with water and a sponge. Each leaf needed to be wiped 3x and then it was clean. After an hour or so of that, I wasn't 1/4 way done, so I stuck the plant in the shower and turned the nozzle on jet spray. I sorta knew it wasn't going to work, but I thought it couldn't hurt. Here's a pic. Any suggestions how I should clean it?

Thanks!
Harper