The valley's dust is fine, alkaline and relentless. It settles on paint within days of a wash, and in a dry spell it never gets rained off.
This page explains what the dust film on a desert car is made of, why it needs a proper wash rather than a dry wipe, and how often local detailers recommend cleaning.
Fine mineral dust, construction grit and, near dry lake beds, caliche: the alkaline powder that comes from calcium-rich soil. Mixed with morning dew it forms a film that clings to paint and glass.
Wiping a dusty panel with a dry cloth drags grit across the clear coat and leaves swirl marks. The correct routine is a wet hand wash, or a rinse with a filter if the supply is hard, before any contact.
Every two to four weeks for a car parked outside. A car parked in a garage can go longer, and a car near construction or dry lake beds needs it sooner.
No. A dry wipe grinds grit into the clear coat and leaves swirl marks. Wash with water and clean media instead.