Vintage fiberglass shades are both decorative and durable, but time leaves them somewhat dirty, whether they have been in constant use or forgotten about for decades. Some fiberglass shades have a texture which appears to attract dirt, which means that upon close inspection you may see quite a lot of grunge. Luckily, fiberglass lampshades are washable at home. In no time, that depressing shade will be looking retro fabulous once more.
Eliminate the lampshade from the lamp, if attached, by twisting the finial counterclockwise.
Take the lampshade outdoors and wipe it gently with a microfiber cloth to remove loose dust inside and outside. If the cloth becomes visibly dirty, rotate the cloth until you find a clean place, or grab another cloth. Doing this outdoors prevents the dust from traveling elsewhere indoors.
Cover a work surface in paper, placing a bowl atop the paper. Squirt 1/4 cup or so of a mild dishwashing soap into a bowl; an exact measurement isn’t necessary. Add a splash of water to help liquefy the soap.
Whip the soap into foamy meringue-like peaks having an electric hand mixer or whisk.
Scoop the foam on the shade with a dry wax, applying the polyurethane to a single place at one time. After a few minutes, then wipe off the foam with a brand new, slightly moist sponge. Dry the area immediately by gently patting it with a lint-free cloth.
Repeat Step 5 until you have washed the whole shade, inside and out.