But by bringing this service in-house, you can save money, make money and develop more business and revenue for your shop.

A Ford dealership shop recently experienced a dilemma: A vehicle had two damaged leather seats, but the factory wouldn’t authorize new “replacement” seats, placing the onus back on the shop. In most cases, the shop would’ve had to absorb the costs involved. But in this case, the shop repaired the seats internally and saved more than $1,600 in production costs and labor.

Would your shop have been able to repair and refinish these interior components? If you’re shaking your head “no,” you’re not alone.

When someone says “automotive refinishing,” very few people think of the inside of an automobile. But as new products and processes are introduced at the original equipment manufacturer (OEM) level, interior refinishing is becoming more of a mainstream service for collision repair facilities. Yet few offer it in-house.

“Refinishing interior parts is virtually an untapped area for collision repair facilities,” says the president of an interior paint refinishing system manufacturer. Most shops, he says, currently use independent, mobile technicians to handle their interior refinishing needs. But since the mobile tech’s work is independent of the shop’s, it’s difficult for facilities to guarantee the work – and it can be costly.

“In the past, many shops shied away from delving into interior refinishing because of the assumed high cost and intense labor involved in the service,” he says, adding that thanks to new products, interior refinishing is easier than ever. “And by bringing the service in-house, interior refinishing offers a brand-new growth area – and profit center – for shops.”

Though the task of refinishing interiors can still be daunting, after I explain how vehicle interiors are manufactured, why certain materials are used and how to refinish interior parts, you can make a more informed decision on whether or not to bring this service in-house.

The “Inside Story” on Interiors
Twenty to 30 years ago, refinishing interior parts wasn’t the challenge it is today. For the most part, interior car parts were finished from the OEM with acrylic lacquer coatings. VOC emission laws weren’t as stringent as they are today, allowing the use of these low-solids, high-VOC coatings. Interior textures, colors and gloss appearances were fairly standard and easy to duplicate, and because some interior parts were still produced from metal, refinishing these parts was no different than refinishing their exterior counterparts.

Today, things are different. Interior parts are now made of plastic and come in different textures and gloss levels. They’re also colored using a variety of methods and coatings: everything from waterborne topcoats to in-mold coatings. More recently, metallic sprayed and laminated processes are also used.

Why is there such a disparity in interior coatings? Primarily because of the wide variety of parts found in interiors and the actual reasoning behind the coating. Aside from the decorative effects, interior coatings can enhance the functional properties of plastic interiors. The coating can improve the durability and the chemical and abrasion resistance of the plastic.

The primary uses for interior coatings include:

Functional. Interior coatings are designed to impart weatherability, such as UV resistance, as well as chemical and antimicrobial properties of parts frequently exposed to skin, including seats, door handles and the steering wheel. OEM interior coatings are also specially formulated to resist chemicals in products such as suntan lotion, insect repellents and glass cleaners. The chemical resistance property in plastic coatings was introduced primarily due to the increasing number of sport utility and recreational vehicles in the market today. As these personal and vehicle care products change in composition, the OE finish must also change to maintain chemical resistance of these new formulations.

Ergonomics. Many hard plastics are finished today for ergonomic reasons, such as soft-touch coatings that give the part a softer and more supple feel. Often, this is done to enhance the value of an economy vehicle.

Decorative effects. OEMs are using more metallic colors for automotive interiors, mainly for decorative purposes. Interior trim parts are refinished to match exterior metallic finishes – a look that’s accomplished by using molded-in, metallic-sprayed or vacuum-formed laminated processes. Many OEMs are also including lighter colors in automotive interiors – a look that hasn’t been used in quite some time. In the past, lighter colors caused a problem with veiling glare, especially from the instrument panel (veiling glare occurs when the color of the instrument panel projects onto the windshield, which can cause a visibility hazard). Today’s OEM coatings address this problem.

Part I: Coating Interiors at the OEM Level
A variety of methods are used at the OEM level for coating plastic interior parts. One of the most common methods is a spray application. Sprayed interior parts include the instrument panel, steering wheel, airbag, knee bolsters, center tray console parts and door components, such as the dip tray, door handles and arm rests (if they’re hard parts).

Another OEM coating process is in-mold coating, in which a coating is sprayed into the plastic part mold. This paint is dried rapidly using heat, and followed by an elastomer that’s injected into the mold to impart the shape and texture of the part. Typically, only steering wheels are made using this process; all other plastic parts are molded in color (pigment extruded into plastic) or spraypainted after molding.

To achieve the look of wood grain, metallic or chrome, OEMs rely on a vacuum-formed laminating process. In this method, a film is placed into a mold with the desired color or appearance (wood grain, stone, etc.). This film is drawn against one cavity, the mold is closed and the plastic is injected against the film. Another method to achieve this look is called hydrographics, in which the film is dissolved over a pool of water. Similar to the theory of oil and water, the film remains in place. The plastic part is pulled through the film (similar to dying Easter eggs) and is then coated with a clearcoat finish to provide protection.

Part II: Refinishing Interiors at the Shop Level
If a vehicle enters your collision repair facility in need of a new interior part, most of the time the new part can be ordered pre-painted from the OEM to match the vehicle’s interior. But many systems are available for collision repair facilities to refinish interior parts, including acrylic lacquer, waterborne and vinyl coatings. These coatings can be applied through both spray guns and aerosol applications. Some are even applied with a sponge. As with any refinishing job, refer to the manufacturer’s specifications regarding recommended refinishing procedures.

Whether the interior part is painted, bare plastic or leather, it’s important to follow a few basic processes and procedures:

1. If the part is painted, begin by cleaning the part with soap and water, followed by a solvent-borne wax and grease remover.
2. Lightly abrade the part with a medium-duty scuffing pad, paying careful attention to the OE texture. Don’t sand aggressively enough to disrupt this texture.
3. At this point, you can typically apply the appropriate topcoat.

In cases where the part is bare, non-coated plastic:

1. Thoroughly clean the part with a medium- to light-duty scuffing pad. Cleaning is the most important step to guarantee adequate adhesion. Similar to refinishing exterior bare plastic parts, begin by using soap and water.
2. Use your scuffing pad to apply a solvent-borne plastic cleaner on all sides of the part. This will help to clean the part more thoroughly, while lightly abrading the part. This light sanding or abrading will increase the part’s surface area, which can help to improve the adhesion of the coating. Be careful not to sand too aggressively or you risk disrupting the OE texture, making it hard to duplicate.
3. Apply a plastic adhesion promoter.
4. Apply the topcoat color.

Refinishing leather and vinyl is similar to the process used for painting plastic parts:

1. Thoroughly clean the part.
2. Lightly scuff the surface to improve the adhesion.

Note: Leather and vinyl are very flexible substrates, which can lead to paint failure if the chosen system is too brittle, so be careful with any recommendation of dye. Dye isn’t photo stable, meaning it will fade quickly – even in indirect sunlight. Note that some dyes are better than others, and systems are available that work well for refurbishing.

Show Me the Money!
Just how much money can you earn by performing in-house interior refinishing? Since interior refinishing is a fresh arena for shops, it’s difficult to predict. But it’s an area that provides endless opportunities for growth, in part because OEMs are relying more and more on plastic for interior parts.

Though making profit predictions is difficult, real-life examples best illustrate your profit potential:

A shop was recently faced with the task of replacing two quarter panels. Instead of using a mobile interior refinishing tech, the shop refinished the interior parts in-house – and saved $240 in labor costs. What could you do with that extra money? Anything you wanted. A

A Word of Caution About Air Bags While it’s relatively simple for collision repairers to refinish most interior plastic parts, technicians should note an area of caution with regard to a vehicle’s air bag and its components. Federal specifications for paint film build are very specific for air bags, due to the “grenade effect,” or the ability of the air bag to deploy without shattering the paint, which can cause severe personal injury to the occupant. An additional concern is the potential for degradation of the plastic from the solvent and even non-deployment of the air bag due to high film build of the refinish paint coating. For these reasons, most air bag coatings contain wax, which prevents adhesion of the topcoat and prohibits it from being refinished. While OEMs have specific recommendations and guidelines for repairing and refinishing air bags, most OEMs don’t recommend completing this task.

Writer Ken Phillips is the product specialist/vehicle repair for Sherwin-Williams Automotive Finishes Corp.