Keeping Up Appearances – Structure, maintenance, and restoration of interior wood trim
Keeping Up Appearances
Structure, maintenance, and restoration of interior wood trim on your Mercedes-Benz
by Gary Anderson & Richard Simonds
Why do we still have wood trim on the interiors of our automobiles? The answer is rooted deep in our psyches: There is an inherent attractiveness in a lovely wood-grain pattern that is unique to a given automobile, and wood trim conveys an intangible feeling of heritage and luxury. It’s not surprising, therefore, that Mercedes-Benz offers interior wood trim at every level in its model lineup.
Once upon a time, when cars were only one step removed from carriages – with most of the basic structure consisting of metal tacked over wood frames – some attractive wood grain peeking through within the interior did make sense. And without much in the way of weatherproofing, temperature swings weren’t excessive.
But in our modern world of automobiles manufactured almost entirely with metal alloys and synthetic materials, wood trim doesn’t seem to make sense. After all, the typical car may be parked outside for hours or days with inside temperatures that could be near zero or 150 degrees or higher, and then heated or cooled within minutes to temperatures that are comfortable for the occupants. Any exposed wood is going to expand or contract, putting a strain on both the structure and the finish of the wood.
Nevertheless, over the past 50 years, engineers and designers have figured out how to install wood trim in automotive interiors so that we can enjoy the appearance of fine wood furniture without the vulnerability of the traditional materials.
W111/W112 instrument binnacle and dash ready for final staining and finishing.
Structure of interior wood trim
The attractiveness of the grain in the wood trim actually is only a few millimeters thick, consisting of a thin veneer shaved in large sheets from logs of carefully nurtured trees. To compensate for the wide and often rapid variations in temperature, as well as make maximum use of rare and expensive woods, the trim pieces are composed of multiple layers of wood and other materials.
Under the grained veneer, typically two layers of a more durable wood are laid with their grains at right angles to one another and to the surface veneer, which minimizes expansion and contraction. Under these wood layers, the base material consists of laminated and carved wood in classic cars built more than a few decades ago, or of formed metal in contemporary models.
To construct a wood trim piece, the grained wood veneer is first laid over and glued down to the wood layers underneath it. Then in a series of steps, the veneer and undersurface is cut and placed over the base piece with glue applied between the two; vacuum and heat are used to press and shape the surface wood to the base piece.
Once the veneer has been shaped and cemented to the base of the component, the surface is sanded with progressively finer grits of sandpaper until absolutely smooth.
Afterward, it is sprayed with the same complex multipart polyester resin developed by major luxury-automobile manufacturers for use on the wood in their new cars. This high-technology resin is designed to be hard enough to resist scratching, but flexible enough to stretch and contract over the wide range of temperatures that automobiles may encounter anywhere they are driven, as well as protecting the wood from ultraviolet rays and other airborne corrosive materials.
Even in this era of carbon fiber and exotic materials, there is nothing quite like the elegance of a well-maintained wood interior in a classic Mercedes-Benz. This beauty is Gloria Loventhal’s unrestored 1960 220S Cabriolet.
Caring for automobile woodwork
Because of the structure of automobile wood trim pieces – and the conditions they face – care is considerably different than that of woodwork in the home. Essentially, there are only two concerns with automobile wood: protection from the effects of sunlight and temperature change and cleanliness. Beyond that, all other care guidelines are concerned with what one should not do.
Maintenance of the wood interior trim starts with protection. The first step is to minimize sun fading by keeping the car inside or under cover whenever possible, using sunshades or a car cover when the car has to be parked outside.
The second step, to minimize cracking of the finish or of the wood itself, is to always open the windows slightly to provide ventilation and mitigate increases in interior temperature.
Beyond that, the challenge is to keep the wood clean so that dust doesn’t get down into the cracks or contribute to scratches when things in the car brush against the wood. Madera Concepts, the leading restorer of wood trim in classic cars in the United States, recommends that the owner use exactly the same methods to clean the wood in the car as would be used to clean the lenses of sunglasses or corrective glasses.
The best tool for cleaning dust from the wood is a good-quality feather duster or an interior vacuum cleaner with a very fine brush attachment. To polish off smudges and residue from cleaning, a soft, clean lint-free cloth made specifically for the purpose of car detailing works well, supplemented on a frequent basis with a soft brush or Q-tip to clean dust and polish residue out of crevices.
If desired, the cloth can be dampened to wipe off the dust, followed by use of a dry cloth to remove any excess moisture from the wood. A glass cleaner, such as Sprayway Glass Cleaner available at Costco, can also be used.
To raise a slight shine on the finish, Madera Concepts suggests that a good-quality quick-detailing product can be used occasionally, and recommended S100 Detail and Wax (www.S100.com). Meguiar’s and Zymol also make excellent quick-detailing products. For protection from UV light and to make dust easier to remove, some detailers recommend 303 Aerospace Protectant, but take care not to let residue build up in corners and crevices.
It is worth noting that there are many products that should not be used. For example, polishes that might be used on wood furniture or automotive finishes often have abrasives that can dull or scratch the protective finish. Dirty polishing rags and paper towels can do the same thing. Popular silicone-based spray products can leave a residue in between panels or on the finish that retains dust, and can get under gauge lenses.
In particular, if the wood finish is damaged by scratches to the point that a soft cloth and spray detailer are no longer sufficient to shine up the surface, or the finish is starting to discolor or crack, the damage is probably beyond what any do-it-yourself hobbyist should attempt to fix. Even if the hobbyist could manage to remove the high-tech finish, the veneer underneath can easily be damaged, and professional restoration to remove and replace the veneer may be the only way to repair the trim.
Restoration of wood trim components
Although wood restoration is discussed in most Mercedes-Benz restoration articles, nearly every author says something to the effect that “If you want your wood to look as good as when it left the factory, if you are entering a concours d’elegance judging, or if you want to get the best price for your car when you sell it, have the woodwork restored by a professional!”
Discolored pieces can be refinished, missing veneer can be replaced, and even broken trim pieces can be restored if the restoration professional can fabricate the parts to the correct shape. High-end restoration shops have many templates and molds for a variety of wood-laden vehicles. When choosing a shop, make sure to inquire with other customers about their experience before consigning your own pieces to its care and repair.
One note that may seem counterintuitive: Most shops that specialize in restoring automotive interior trim do not perform any of the disassembly required to remove the wood trim because that is a completely different job that requires special knowledge and experience. This work will have to be done beforehand by a restoration shop that is experienced in disassembling M-B interiors, or by the do-it-yourselfer who is knowledgeable about removing interior pieces without breaking them or making it more difficult to reinstall the parts.
When the restorer receives the pieces for repair, a specialist will inspect them to determine whether an item can be restored by simply removing the protective finish from the veneer and refinishing the piece, or if the veneer itself must be removed and replaced. For reference, refinishing costs about two-thirds the cost of removing and replacing the veneer.
In cases when damage is limited to one or two pieces, the repair might be limited. However, because the color of the wood surface will have changed over time, refinishing the entire interior is likely to be more satisfactory to achieve a consistent appearance. If the veneer needs to be replaced, restoring all wood interior is almost imperative to ensure the grain and color matches throughout, including areas where the grain is book-matched – where two successive layers of veneer sheet from the same piece of wood are used to achieve a symmetrical pattern.
What does work like this cost? An experienced shop like Madera Concepts will draw on its extensive experience to charge by the pieces in the interior rather than a time-and-materials basis, providing an estimate of the charges in advance. As an indication of costs, a small piece of individual trim might cost as little as $100 to $200 to refinish. Complete reveneering and refinishing the wood interior in a high-end model such as a 1959 220SE can cost in the range of $3,500 to $5,000. This element of the restoration is not inexpensive, but good quality wood trim will greatly enhance the value of a classic car.
Madera Concepts’ Tony Gonzalez (in black) explains the veneering press, used to mold veneers to compound surfaces, such as W111/W112 instrument binnacles.
Jeff Wayco outlines the working of the spray booth, where the same complex multipart polyester resin finish developed by the luxury automotive industry is applied to wood trim.
Skillful use of the polishing wheel will put just the right sheen on finished woodwork.
Thanks to Jeff Wayco and Tony Gonzalez of Madera Concepts for their assistance in preparing this article. Because their story is so interesting, it bears retelling here.
In the early 1900s, Oscar Grunau, one of England’s premier automobile upholsterers, designed and installed a lacquered wooden dashboard in a dignitary’s automobile. Response was so favorable that requests for wooden dashboards quickly outnumbered those for his upholstery services; Grunau soon converted to manufacturing wooden interior trim. His son grew up “at the bench,” and after directing the firm for many years, took over upon his father’s death. Under the name Rokee, the firm manufactured trim for a number of independent European luxury-car manufacturers, and many of the craftsmen who apprenticed at Rokee left to staff the wood divisions of companies like Rolls-Royce and Jaguar.
In 1977, French automotive designer Alain Clenet established Clenet Coachworks to produce a neo-classic automobile in Goleta, California. He sought out Rokee to supply the interior wood. When Grunau decided to close his company in the face of declining global demand, Clenet purchased Rokee’s machinery and materials and contracted with Grunau and his chief veneer specialist to set up a woodworking shop in Clenet’s Goleta factory. Wayco and Gonzalez became Grunau’s apprentices, learning the craft from him.
When demand for expensive custom automobiles dried up in the United States in the late 1970s, Clenet in turn went out of business and Wayco and Gonzales established Madera Concepts in Goleta in 1982.
Since that time, the goal of Madera Concepts has been to provide the highest quality automotive woodwork restoration services. Now with more than 32 years of experience, the firm is the leading source of Old-World woodwork craftsmanship to hobbyists around the world.
Shining example: a beautiful W111/W112 dash restoration recently completed at Madera Concepts.
This article originally appeared in the September-October 2014 issue of The Star, the award-winning magazine of the Mercedes-Benz Club of America. It is made available with permission. For more information on the club, click on www.mbca.org.
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