How can you tell if a car wash is safe for your paint?

Before you pay

Look at the wash material through the tunnel entrance. Closed-cell foam looks like dense, smooth, brightly coloured fingers. Cloth is fine when it is clean and saturated; bristle brushes are a relic. Anything that looks matted, grey or frayed has carried a lot of grit.

Look at the lot and the building. A tunnel whose signs, lights and vacuum stalls are cared for is usually a tunnel whose equipment is cared for too.

At the entrance

A good express wash has an attendant prepping cars by hand with a pressure wand — bumpers, grilles, rocker panels, wheels. That knocks off the heavy grit before anything touches the paint.

The pre-soak should go on and be given a few seconds to work before the first wrap touches the car. Chemistry that is still dripping onto the windshield as the brushes arrive is doing half its job.

In the tunnel

The wash material should be wet and foamy when it meets the car and should sound soft — a steady hiss and slap, not a clatter. Wheel and tire brushes should be separate, low-mounted tools that never touch the paint.

The conveyor matters for wheels. Look for a guide rail that is in good repair and an attendant loading cars straight onto it; curb rash on a wheel usually happens at the entrance, not in the wash.

After the wash

Stand in the sun and look along the side of the car at a low angle. New fine scratches, a grey haze on dark paint, or grit left in the lower door edges are all signs the tunnel is not being looked after.

If an attendant towel-dries at the exit, look at the towels. A clean stack and a bin for used ones is right; one damp towel doing car after car is not.

These are the same observations behind the Paint Safety score on every review on this site.

Short answers