Snow foam, done right

A good snow foam clings, softens road film and drags dirt down and off the panels under gravity. The point is to make the contact wash safer by removing as much grit as possible without touching the paint. It works in a pressure-washer lance or a garden-hose foam cannon.

1. 1

   Dilute for your gear

   Pressure-washer cannon: about 100ml foam topped with warm water. Hose foamer: richer, about 1:5. Warm water makes thicker foam.

2. 2

   Rinse off loose dust

   A quick rinse first means the foam spends its energy on bonded film, not loose sand.

3. 3

   Foam bottom up

   Start at the sills and work up. If you foam the roof first, the lower panels — the dirtiest — get the shortest dwell time.

4. 4

   Dwell three to five minutes

   Let it hang and slide. Never let it dry. In summer sun that might be two minutes; keep an eye on the edges.

   Bay tip · Out of direct sun, always. Dried foam leaves a film that needs another wash to remove.

5. 5

   Rinse top down

   Rinse thoroughly from the roof down, then go straight into your two-bucket wash.