Headlight restoration cost: what you pay for and how long it lasts

Two cars with yellow headlights can need very different amounts of work. These are the things that move the price up or down:

• How deep the damage goes. A light haze sits in the top of the old coating and sands away quickly. Heavy yellowing, a chalky white crust or a web of fine cracks (called crazing) means the coating has failed all the way through, and the lens needs more sanding steps before it can be polished clear.
• One lens or a pair. Most people restore both, because one clear lens beside a cloudy one looks odd and lights the road unevenly.
• Size and shape. A large wraparound lens on a pickup or SUV has more surface to sand and polish than a small flat lens on a compact sedan.
• Access around the lens. The paint, grille and bumper next to the headlight have to be masked so the sanding never touches them. Lenses that sit tight against a hood edge or a chrome trim piece take more care.
• Earlier home attempts. Patchy kit sealer has to come off first.
• The protection at the end. The coating applied last is what keeps the lens clear. A hard UV-cured clear layer takes more time and material than a wipe-on product, and it is built to last longer.

One thing restoration cannot change is what is inside the housing. Moisture, a browned reflector or a broken seal are not surface problems, and we will say so before any work starts.

Modern headlight lenses are polycarbonate, a tough plastic that would yellow quickly in sunlight on its own. The factory protects it with a thin hard coat. Years of ultraviolet light break that coat down, road grit sandblasts it at freeway speed, and once it starts to fail the plastic underneath begins to oxidize.

AAA's release on its 2018 testing reported that on low beam, the deteriorated headlights gave off just 22 percent of the light of a new headlight. The same release says lenses can begin to show deterioration as early as three to five years, depending on where and how the car is used. A car that bakes in a Santa Clarita or Pomona driveway every afternoon, or sits on a sunny street near the coast all year, lands at the fast end of that range.

Darkness raises the stakes. IIHS, the highway safety research group, notes that about half of traffic deaths happen in the dark or at dawn or dusk, which is exactly when a hazy lens hurts most.

Sources: AAA Newsroom, Dangers of Driving with Cloudy Headlights (Dec. 11, 2018); IIHS, Headlights.

In AAA's small test sample the home kit came close to the shop result on light output. Where a kit can fall short is the coating it leaves behind. If you try one, a few habits help:

1. Tape off the paint and trim around the lens.
2. Sand wet, and keep going with each grit until the whole lens has an even, frosted look before moving to the next one.
3. Do not skip the finest grits; leftover sanding marks scatter light like haze.
4. Apply the sealer the kit includes, and follow its curing directions exactly.

Toothpaste or a polishing compound alone can make a lens look better for a while, but it leaves the lens bare, and bare polycarbonate yellows again fast. A professional restoration removes all of the failed coating, refines the surface through progressively finer abrasives, and finishes with a durable UV-protective clear layer, which is the step that decides whether the result lasts a season or years.

Sources: AAA, Headlamp Lens Deterioration (December 2018 report).

Southern California is hard on headlights. Long commutes on the 405 and the 5 mean hours of grit and stone spray, and a car parked outside in Pasadena, Torrance or Santa Ana takes direct sun nearly every day of the year.

Because restoration needs no spray booth, we do it where the car already sits, whether that is your driveway, your office lot or a parking structure in Anaheim. Most jobs are done the same day. If the lenses sit next to a scuffed bumper or faded paint, we can look at those on the same visit; see bumper repair and paint correction.