Exterior trim care

Exterior trim care and interior plastic care for your car

What does plastic care do? After cleaning, it lays a thin film with UV absorbers on plastic and rubber. The film slows fading from sunlight, keeps plasticisers in the material and stops the dashboard and bumper trim from turning grey and brittle. At Detailing1 you can choose from products by Koch-Chemie, Meguiar's, SONAX, GYEON and CarPro.

Exterior trim care – and plastic care inside the car – is the protective step after cleaning. It applies a thin film of silicone oils or polymers and brings UV absorbers with it: molecules that soak up high-energy sunlight and release it as heat before it can break the plastic's molecular chains. Without that protection, plastic loses plasticisers over the years, fades and turns brittle. That goes for the dashboard inside just as much as for bumper strips and wheel arch trims outside.

• UV is the enemy, not dirt. A dashboard doesn't go grey because it's dirty, but because the sun blasts it through the windscreen. That's why the damage shows first where the sun hits most directly – on the top surface above the passenger airbag.
• One concentrate covers both worlds. Koch-Chemie Hydro Plast Care „Hpc" Plastic Care Concentrate (Water-Dilutable) can be mixed thin for interior surfaces and stronger for weathered exterior parts. One bottle, two jobs.
• The best seller is an interior product. Koch-Chemie Top Star „Ts" Interior Plastic Care clearly leads our sales list in this category and delivers a satin-matte finish with no glare into your line of sight.

Detailing1's tip from the shop: What we see again and again at Detailing1 is overdosing. The thinking behind it sounds logical – more product, more protection. But plastic can only absorb a limited amount; everything beyond that stays on top as a film, shines in patches and attracts dust.

Put the product on the towel or applicator the manufacturer specifies and work it in as the instructions say. Remove any excess as those instructions describe. A specified buff-off decides between matte and even or greasy and blotchy. Keep it off the steering wheel and pedals completely – that's where you need grip.

UV absorbers keep plastic black

Plastic in a car ages in two ways, and both happen slowly enough that you only notice once they're visible.

The first is UV radiation. Ultraviolet sunlight carries enough energy to cut through the plastic's long molecular chains. The surface becomes microscopically rough, scatters light diffusely and so looks grey instead of black. In practice you'll notice the surface looks dull even though it's clean – at that point, washing won't help any more.

The second is the loss of plasticisers. These are additives that keep plastic flexible. Over the years they migrate to the surface and evaporate, faster in the heat. The plastic hardens and develops fine cracks under mechanical stress. With door seals, that's why they freeze shut in winter and tear when you open the door.

Plastic care tackles both. The UV absorbers catch the radiation before it triggers chain breakdown, and the applied film slows plasticisers from evaporating. For you that means: the part stays black and flexible for longer. Neither can be reversed – faded plastic stays faded, so care from new is more effective than care once the damage shows.

Silicone oil or silicone-free is a question of location

The dividing line in the range runs between two groups of actives, and both have their place.

Products with silicone oil give an instant rich, deep black and soak in quickly. Their downside shows inside: silicone oil is volatile, rises into the air when it's warm and settles on the inside of the windscreen. The film there is thin and only noticeable against the light, where it costs you visibility as a greasy haze. If you're always complaining about misted-up glass, this is where to start.

Silicone-free products work with polymers. They take a little longer to look rich and stay where they were applied. That makes them the cleaner choice for the interior. SONAX PROFILINE PlasticCare Plastic Care belongs to this group.

Outside, the maths flips. There's no glass for anything to settle on, but there is rain and the pressure washer. Silicone-based products stand up to that better and deliver the deep black you want on wheel arch trims and bumper strips. SONAX XTREME Plastic Gel „Exterior" Plastic Care is made for exactly that.

There's a third group sitting between the two: water-based emulsions. They carry the active finely dispersed in water rather than a solvent, so they soak in more slowly and barely smell. For cars used every day, that's a practical plus – you can get straight in after treatment without a chemical smell. The trade-off is durability, which is shorter than with solvent-based products.

The engine bay has its own answer. Koch-Chemie Motorplast „Mp" Engine Preservation is built for heat and protects plastic covers and wiring looms after an engine wash.

Matte goes on top, gloss goes on the door

The finish isn't a question of quality but of location – and you can answer it by where the part sits.

The dashboard gets matte. It sits almost horizontally under the windscreen and reflects straight into your field of view when the sun is low. Any extra gloss makes exactly that reflection worse. Top Star „Ts" is our standard recommendation for this.

On door cards, the centre console and in the footwells, reflection doesn't matter, so it comes down to taste. If you like a rich shine, you'll find it in Koch-Chemie Cockpit-Super-Pflege „Csp" Interior Plastic Dressing (Glossy), with no compromise on protection.

For rubber and soft plastic there are both versions. Koch-Chemie Rubber, Plastic & Vinyl Care „Gkv" Plastic Care covers seals, cubbies and vinyl surfaces; its glossy sibling is Rubber & Plastic Care Gloss „Gkg".

Badly faded plastic remains a special case. When black trim is already grey and blotchy, the colour has gone from the surface and no oil film will bring it back. Koch-Chemie Kunststoff-Färber „Kfs" Black Plastic Care therefore works with pigments rather than oil and puts colour back. That's cosmetics with limited durability – and the only alternative to replacing the part.

Apply thin and take off the excess

The routine is short, and the mistakes all happen at the same point.

Cleaning comes before care – and completely. Care on uncleaned plastic seals in the dirt film; the result is a greasy surface that grabs dust faster than before. You'll find the right products for the step before under Interior cleaner.

The surface has to be dry. Leftover moisture stops the film from laying down evenly and leaves clouds that only show once it's dried. A second, dry towel after cleaning sorts that out.

Then the product goes onto the towel or applicator the manufacturer specifies. Work it in evenly as the instructions say and remove the excess as they describe. Skip a specified buff-off and you get exactly the blotchy, greasy look that gave plastic care its dubious reputation.

Steering wheel, gear lever and pedals don't get treated. A silicone or polymer film on the steering wheel rim makes it slippery, and that's not a cosmetic problem. If you want the steering wheel clean, clean it and leave it untreated. The same goes for seat belts and the tread areas of the floor mats.

Outside, the same routine applies with one addition: weathered plastic parts should be degreased before the first treatment, otherwise the new film sits on remnants of the old one and lasts far less time.

One thing that regularly causes trouble outside is the edge where trim meets paint. Plastic care on painted surfaces leaves a greasy haze that only a degreaser will shift, and on a freshly sealed bonnet it gets in the way of water beading. So work along the edge with a narrow applicator, and on wheel arch trims, mask off the adjacent paint if in doubt. Two minutes' effort saves half an hour of rework.

Durability depends more on location than on the product. Inside, sheltered from rain, a good product lasts a season and more. Outside, the number of washes decides: every pass with alkaline shampoo takes off some of the film, and a pressure washer speeds that up. Outside, reckon on six to ten washes before it needs topping up. If you don't want to keep track of that, a sealant is the better bet.

The range for dashboards, seals and trim

Our range is compact and covers four areas of use.

For interior surfaces, Koch-Chemie has the widest line-up with twelve products, from the standard matte dressing to the glossy version and the water-dilutable concentrate. The line is matched across the board, so you can mix without risking incompatibilities.

For exterior parts we stock the specialist gels and detailers, including SONAX XTREME Plastic Detailer „Interior+Exterior" Plastic Care, which covers both areas and is enough for cars with little exterior plastic.

For exterior parts there are different routes to protection. According to the manufacturer, SONAX XTREME Ceramic Plastic Sealant is spread thinly with a microfibre towel and wiped off straight away; it mustn't dry on. SONAX quotes up to three months of protection. Curing coatings follow different prep and application.

Prices range from under eight euros for a small bottle of standard dressing to three figures for sealants and pro-size containers. For a single car, the sensible range is at the lower end – 250 to 500 ml covers the interior for several years, because each application only needs a few millilitres. If you treat the exterior too or look after several cars, the concentrate works out cheaper.

Then there's the engine bay, with Motorplast as a use case of its own. THE FINISHER „InsideCare" Interior Care rounds off the range for the interior.

New car, daily driver and weathered vehicle

The condition of the plastic decides which product makes sense – and whether care is even the right tool any more.

With a new car or a young used one, it's about prevention, and that's where the payoff is biggest. A matte dressing on the interior surfaces twice a year, plus treating the exterior parts, takes half an hour all in. The effect only shows after years, but it's clear: a dashboard that's still evenly black after eight years.

With a daily driver that has a few years on the clock, the condition is usually still good enough for standard care. If individual spots are already lighter, look at where they are – if it's the surfaces facing the sun, UV is the cause and regular care slows down the rest.

With a seasonal or rarely used car, things are different from what most people assume. A car that barely moves ages faster inside than a high-mileage one – it often stands in the sun, the interior temperature climbs above 60 degrees, and the heat drives the plasticisers out of the material. Treating all interior surfaces twice a year does more here than any cleaning. A sunshade on the windscreen costs next to nothing and takes the brunt of it.

With a weathered car with grey, blotchy plastic parts, normal care only has a short-lived effect. It darkens the surface for a few weeks and then washes out. Here, to be honest, the plastic dye is the only option with a visible result – and even that is a stopgap.

If you're planning cleaning and care together, you'll find both steps grouped under Interior care. This category is also the care branch of Care products in the Washing & cleaning section.