Dell XPS 18 (1810, Early 2013) - Manual (Page 38)

Cleaning Your Computer
CAUTION: Disconnect all cables from your computer before cleaning it.
Clean your computer with a soft cloth dampened with water. 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
water from the cloth to seep into the computer ports.
NOTE: Do not spray cleaning solution directly onto the display. Only use
products specifically designed for cleaning displays, and follow the
instructions that are included with the product.
38 │ Cleaning Your Computer