Popcorn, also known as a “cottage cheese” ceiling, is a spongy material applied to finished drywall by a compressed-air sprayer. Like acoustical tile, popcorn is installed to dampen sound and reduce or eliminate echoes.

 

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Grease, tobacco smoke, and dust and dirt in general, accumulate on and readily discolor this kind of ceiling. But before you touch it or start cleaning it in any manner, have it tested for asbestos content. If asbestos is present, you'll want to leave well enough alone and let the professionals handle it. Asbestos materials are considered to be safe, so long as they remain intact and in good enough condition that no fibers are wearing off into dust that can be breathed.

Assuming asbestos is not present, cleaning by vacuuming does not work well, unless you are talking about loosely spun cobwebs. Acoustic popcorn adheres to the underlayment very loosely, so it's easy to knock the stuff off the surface unless it's been painted over. Stains can be removed by spraying a bleach-based chemical onto the ceiling; the chlorine bleach strips colors out of most materials.

Contractors are available to do this work. If you do it yourself, cover everything in the room to protect it from the bleach. Wear protective clothing, a mask and eye protection; chlorine mist is toxic in high concentrations. Purchase the chemical at a janitorial supply house and apply it with a garden sprayer or spray bottle. Turn off fans, heating and air conditioning to prevent the mist from moving to other unprotected rooms. Allow treated areas to dry before removing protective covers.

Popcorn may also be painted, but it will have to be cleaned first. Bear in mind that painting will reduce or destroy the effectiveness of the acoustical material.

 

 

Reference:

Don Aslett in The Cleaning Encyclopedia: Your A to Z Illustrated Guide to Cleaning Like the Pros