Dell XPS 18 (1820, Early 2014) - Manual (Page 32)

32 │ Cleaning Your Computer
Cleaning Your Computer
CAUTION: Disconnect all cables from your computer before
cleaning it. Clean your computer with a soft cloth slightly
moistened with water or an approved display cleaner. Do not
use liquid or aerosol cleaners that may contain flammable
substances.
1 Turn off your computer. For more information on turning off your
computer, see Turning Off Your Computer .
2 Moisten a soft, lint-free cloth with either water or a display
cleaner, and wipe the surface of the computer until it is clean. Do
not allow liquid from the cloth to seep into the computer ports.
NOTE: Do not spray cleaning solution directly onto the computer.
Only use specifically-designed cleaning products, and follow the
instructions that are included with the product.