Unpainted black trim is pigmented plastic with no clear coat over it. UV breaks down the surface layer, oils leach out, and what is left is a chalky, oxidized gray surface that scatters light instead of absorbing it.
A supermarket dressing puts oil back on top. It looks black for a week and then washes off, because it never bonded to anything. A trim restoration removes the oxidized layer first and then applies a product that cures onto the plastic — that is why one lasts and the other does not.
Black trim restoration is a $75 to $100 add-on depending on vehicle size. One of the 60 jobs in our documented set was booked specifically for trim restoration.
Painted panels have clear coat over the color. It is a sacrificial UV barrier, and it is the reason paint fades far more slowly than trim. Unpainted trim has nothing over it. The black is pigment mixed into the plastic itself, and the surface is directly exposed.
UV breaks the polymer chains at the surface and drives out the plasticisers — the oils that keep the plastic flexible and dark. What is left is a microscopically rough, porous, oxidized layer. Rough surfaces scatter light, and scattered light reads as gray. The plastic underneath that layer is usually still perfectly black.
That is the whole reason dressings appear to work. Filling the rough surface with oil makes it optically smooth again, so it goes dark. Then rain washes the oil out of the pores and the gray comes back.
In San Francisco this happens fastest on cars parked outside facing the sun, and it shows up first on window surrounds, mirror caps, wiper cowls, bumper inserts and roof rails.
Trim collects everything — wax residue, old dressing, road film, polish dust from previous work. Any of that left in place prevents the restoration product bonding, so this step is not optional.
The dead, porous surface has to come off or you are just filling it again. This is done chemically or with light mechanical work depending on how far gone the trim is.
A product that chemically bonds to and cures onto the plastic, rather than an oil that sits on it. This is the difference that makes the result last through washes and rain.
Applied evenly, excess removed, and given time to cure. Uneven application on trim is far more visible than on paint because the surface is matte.
Restored trim still lives outside in UV. Re-treating periodically holds it, and it is far easier to maintain restored trim than to restore it again from scratch.
| Add-on | Sedan | Midsize SUV | Large SUV / truck |
|---|---|---|---|
| Black trim restoration | $75 | $75 | $100 |
| Exterior Wash & Protection (base) | $100 | $125 | $150 |
| Full Package (base) | $279 | $300 | $350 |
Trim restoration is added to an exterior wash or a full package. Doing it on a car that has not been washed is pointless — the cleaning step is half the job.
The mechanism is UV, so the prevention is a UV barrier maintained over time. Restored trim treated periodically stays black; restored trim left alone for two years in direct sun oxidizes again, just from a better starting point.
Mask trim when polishing. The single most preventable trim problem is white polish residue driven into textured plastic. It is difficult to remove and completely avoidable with masking tape.
Do not use tire shine on trim. Tire dressings are formulated to be slung off by rotation. On a static vertical surface they run, streak and attract dust.
Wash it as part of the car. Trim that stays clean oxidizes more slowly than trim carrying a permanent layer of road film.
And the general point: on a car parked outside in this city, trim, dashboard plastics and headlight lenses are all fading on the same clock for the same reason. If the trim has gone gray, look at the headlights as well — they are usually next.
Of all the exterior add-ons, this is the one with the biggest visual return per dollar on a car more than five years old. Gray trim reads as neglected in a way that dirty paint does not, and it is what people notice in photos when you are selling.
Pair it with headlight restoration at $50 per headlight, $100 for the pair, and an older car looks substantially newer for $175 of add-ons on top of the wash.
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It is a $75 add-on and it changes how the whole car reads. Booked with any exterior detail.