IDA Certification — Study Guide: Leather
Well it’s time to get back to the presentation of information needed to successfully complete the detailing certification exams offered by the International Detailing Association. This month, the discussion centers around the care of automotive leather.
The International Detailing Association offers it’s Certified Detailer program to both members of the association as well as non-members. The program currently consists of 10 tests that assess the taker’s background knowledge of detailing. This month’s column is one in an on-again, off-again series that is designed to present a study guide for those who are interested in taking the tests. Get more information or sign up for the tests at www.the-ida.com.
SEAT UPHOLSTERY PRIMER
Upholstered vehicle seating requires specialized cleaning and care, just like any other interior or exterior surface. As a point of vocabulary clarification, the word “upholstery” refers to the covering of a seat. Many think of the term “upholstery” as referring only to fabric seats. In truth, a seat may be upholstered in any number of materials. Those materials typically used in automotive applications are: vinyl, leather, fabric (velour), and sport cloth.
You will find that, in newer vehicles, the most common upholstery is leather, followed by sport cloth. Seats upholstered in vinyl are not as common anymore, but not extinct. A newer but still rare seat upholstery choice is suede. True suede is actually the rough side of leather, finished to have a velvet-like nap. A popular form of suede is “nubuck,” which is a finer grade of suede. The difference between suede and nubuck is one of appearance and feel, but they are both natural products from cowhide and are cared for in the same manner.
Often, several materials are used to upholster a seat. For example, a common description used by auto manufacturers is “leather trimmed.” This typically means that some of the seat, usually the seat face, is upholstered in leather and the rest in vinyl. Only in the finer vehicles is the entire seat (front, face, sides, and back) covered completely in leather. Similarly, some fabric seats have vinyl side panels and backs.
Then there are the upholsteries that look, feel, or are labeled to be very similar to natural leather. “Leatherette” is an upholstery that was used for many years in Mercedes vehicles. It is actually a vinyl product. “Pleather” is a proprietary example of a newer type of vinyl that is very close to the look and feel of leather. It is used mostly in recreational vehicles but I have seen it in a couple of cars recently.
During the standard interior detail process, the seats will have been thoroughly vacuumed before they are cleaned. During the vacuum step, make sure to clean any grit and debris from the seam areas. Spread the bolsters open with your hands and use a crevice tool and a soft nylon brush. Next, we will discuss the special equipment, chemicals, and techniques necessary to properly clean and condition leather seats.
Virtually all leather used for automotive purposes is coated with a layer of protection. In common parlance, leather is “dyed” to give it color. In fact, this color coating is typically sprayed onto the leather. This coating allows the vehicle designer to color the leather seat upholstery to compliment the color scheme of the vehicle interior. The coating performs a more important benefit of protecting the leather from wear and tear.
The quality grade of the leather used in an automobile may vary by manufacturer. In general, the finer grades of leather will be used in more expensive vehicles. Nonetheless, virtually all of these leathers are coated in a fashion similar to that mentioned above. Interestingly, the quality of the coating can also vary. I have personally witnessed the accidental removal of leather color coating from newer, supposedly high-end vehicles. Thus, it is important to remember that harsh scrubbing techniques are typically not recommended for any automotive leather.
A less common type of leather used in automotive applications is aniline dyed. Aniline dyed leather uses a clear coating instead of a pigmented solid paint color. As such, the natural grain and imperfections of the leather surface are visible. This type of dyeing approach is more popular in household furniture, but some vehicles do use it, such as the Ford King Ranch pickup.
CLEANING LEATHER SEATS
As mentioned earlier, an increasingly large majority of modern vehicles have seats that are upholstered in leather, or are at least “leather trimmed.” Sometimes it can be difficult to determine whether or not the material is leather or vinyl, as vinyl grain-stamping techniques can closely imitate leather grain and feel. (Take comfort, for I, the supposed “expert,” have been fooled more than once.)
One way to detect the difference is to push your thumb down into a panel, yielding a wavy “hill-and-valley” pattern around your thumb. As you press down, look into the valleys; if you see tiny wrinkles within the valleys, you are probably dealing with leather. Vinyl will not produce these wrinkles. Additionally, over time leather will naturally develop scuffs and character lines.
If you are not sure, simply treat the upholstery as if it were leather. The cleaners and conditioners recommended for use on leather are also safe on vinyl. However, the cleaners used for vinyl are not necessarily safe for leather.
Many “all-purpose” cleaners can be too caustic (alkaline) for safe use on leather. That being said, it is possible to use a mild solution of a mild all-purpose cleaner to effectively clean leather. Moreover, products designed for cleaning leathers used in applications other than automotive upholstery are not generally recommended for use on automotive leather (e.g., Saddle Soap). The important factor in choosing any chemical for use on leather is that the chemical is close to neutral on the pH scale. Hence, nothing caustic and nothing acidic.
After vacuuming, the typical technique used to clean the leather is to spray the appropriate cleaner onto a section of the seat, then agitate with a soft brush or other scrubbing appliance. A preferred brush bristle is natural hogs-hair or horse-hair. Stiff vinyl bristles are not recommended. Other technicians prefer to use a soft scrub sponge to agitate the leather surface. Regardless of the scrubbing appliance use, wipe away the remaining cleaner and dirty residue with a clean utility towel. A terry towel works fine but some technicians prefer to use a microfiber.
An increasingly popular method for cleaning leather is to use dry vapor steam. An industrial steam machine
produces dry vapor that loosens dirt on the leather surface, even in the deep character lines and creases. The high-temperature steam also sanitizes the leather while it cleans. Care must be taken when using steam, as it can lift the protective coating if used too aggressively. Additionally, care must be taken with perforated or ventilated leather seat
covering. Nonetheless, most technicians who utilize dry vapor steam in their detailing operation agree that it cleans better than the spray-brush-wipe technique.
Once clean, the leather needs to be properly conditioned. Use only leather conditioners designed for use on automotive leather. Using saddle products or those for furniture leather may actually damage the coatings typically used for automotive leather. Apply your conditioner liberally, allow it to soak in, then buff off the excess with a clean utility towel. I recommend using a conditioner with ultraviolet blockers, as the sun is the one element that will cause the most damage to leather, next to normal use.
Dressing designed for use on rubber or vinyl should never be used on automotive leather. This type of dressing can leave the leather feeling greasy, looking unnaturally glossy, and slippery for the passenger sitting in the seat. And some dressings, especially those with a solvent base, can actually damage the leather.
Appropriate leather dressing will not only make the leather look and feel nice, it can actually help to preserve the natural material. Although I mentioned that leather is protected with a coating of paint (“dye”), that layer of paint breaks down over time. In fact, there are microscopic cracks in new leather coatings within six months of use. The appropriate conditioner will penetrate those cracks and lubricate the collagen that makes up the top layer of the leather that is just underneath the coating. The more lubricated this layer remains, the longer it will take for the leather to break down.
Speaking of which, normal wear-and-tear of leather is unavoidable (unless you never sit on the seat). Indeed, those microscopic fissures described earlier will lead to scuffing, which leads to cracks. It can take months or years for this process to occur, depending on the amount of use the seat gets and the quality of the original upholstery.
Most of us have had the occasion, when cleaning a driver’s seat, to note the dark patches that occur upon moistening the seat with leather cleaner. This is usually exposed bare leather in a spot where the coating has worn off. Sometimes these patches look like dirt, prompting the customer to ask if the area can be cleaned. Unfortunately, standard detailing techniques will not fix leather scuffing or cracks. These types of damage must be repaired by an interior surface repair technician.
The professional detailing technician must be expert at cleaning and protecting all of the surfaces on a vehicle. This includes leather, which is an especially sensitive material that requires specific techniques and care. Learning such techniques will help the technician to provide superior service and results, adding to the value provided to the customer through preservation of the automotive leather.
Prentice St. Clair is president of Detail in Progress, a San Diego-based automotive reconditioning consulting firm. To contact him, e-mail Prentice@DetailinProgress.com or call (619) 701-1100.