Auto Laundry News - February 2013

IDA Certification — Study Guide: Interior Detailing, Part II

By Prentice St. Clair

This month, let’s get back to the discussion of interior detailing as it relates to the study guide for the certification tests offered by the International Detailing Association’s (IDA) Certified Detailer (CD) program.

The IDA offers its CD program to both members and non-members of the association. 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 interested in taking the tests. Get more information or sign up for the tests at

As mentioned in the December 2012 issue, the standard interior detailing process generally includes these steps:

1. Remove customer belongings
2. Vacuum and air purge
3. Check headliner
4. Clean vinyl and plastic panels
5. Clean seats
6. Clean carpets
7. Dress vinyl and plastic panels
8. Condition leather
9. Clean interior glass
10. Deodorize as necessary

I covered the first five steps in the December issue. Now let’s continue with the next step of the interior detail process.


Upholstered vehicle seating requires specialized cleaning and care. The word “upholstery,” refers to the covering of
a seat. The materials typically used in automotive upholstery applications are: vinyl, leather, cloth, and suede.
The most common upholstery is leather, followed by cloth. Vinyl seats are not as common anymore. A newer upholstery choice is suede, which is the rough side of leather, finished to have a velvet-like nap. A finer grade of suede is “nubuck.” 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, “leather trimmed” seats have a seat face that is upholstered in leather, but the remainder of the seat is made of vinyl. Only in the finer vehicles is the entire seat covered in leather. Similarly, some cloth seats have vinyl side panels and backs.

During the standard interior detail process, the seats will have been thoroughly vacuumed before they are cleaned. While vacuuming, pay special attention to removing grit and debris from the seam areas — spread the
bolsters open with your hands and use a crevice tool and a soft nylon brush.

Leather Seats
The two most common methods currently used to clean leather are: manual techniques, using leather cleaner and a brush; and steam.

In the case of manual techniques, a cleaner designed specifically for automotive leather is applied to the leather, then agitated with a soft hogs-hair or horsehair brush. Then the remaining cleaner and dirty residue is wiped away with a clean towel. A terry towel works fine but some technicians prefer to use a microfiber.

A dry-vapor steam machine can be even more effective at cleaning leather than manual techniques. No chemicals are necessary when using steam, which loosens the dirt with minimal agitation and has the side benefit of disinfection. Leather seat care will be covered in depth in an upcoming separate study guide.

Vinyl Seats
Seats upholstered in vinyl can be easily cleaned using a mild solution of your favorite multi-purpose cleaner, a soft scrub brush, and a utility towel. Spray the cleaner directly onto the seat, scrub with the brush, and wipe away the remaining cleaner residue and dirt. We generally use vinyl and plastic dressing on most surfaces inside the car. Vinyl seats, however, should not be dressed using standard dressing, which can leave the seats slippery. Instead, dress vinyl seats using automotive leather conditioner.

Cloth Seats
Cloth seats can be cleaned using a dry-vapor steam machine or hot-water extractor. A hot-water extractor will provide better results than cleaning by hand or with a wet-dry vacuum. However, even the most powerful extractor tends to leave the seats quite damp. A dry-vapor steam machine, on the other hand, will not do this since it uses much less water than the extractor, and the steam machine only cleans the surface without soaking the foam underneath the surface.

Whether using steam or extractor, the cleaning process is similar: Spray the seats lightly with cleaning solution designed for cloth, scrub with a stiff-bristled scrub brush, and “rinse” using the machine. Tougher stains can usually be treated using the same favorite spot removers that you like to use on carpeting.

A couple of notes: When using steam, it is often not necessary to use any chemicals for cleaning cloth seats. If using an extractor, place an air mover on the seat to speed up the drying time. Once the seats are dry, you can apply liquid repellent “cloth guard” as an extra service (with an extra charge).

Suede or Nubuck
The care of suede or nubuck is generally limited to dry brushing or careful use of a steam machine. You should have a suede brush on hand (available from a shoe store or furniture store), but, in a pinch, a stiff-bristled, clean nylon brush or even a wire brush can work, if used carefully.


“Carpeting” includes carpeted floor mats, the carpeting on the floor of the vehicle, and any other surface inside the car that is covered in carpeting-like material (like the lower part of some door panels.

Mats should be removed from the vehicle and cleaned early in the interior detailing process (perhaps after Step 2). By doing so, the mats have a chance to fully dry (either by the sun or using air movers) by the time the detail is complete. Heavily soiled mats may need to be blasted with a pressure washer before using one of the cleaning methods mentioned below. (However, do not use the pressure washer inside the vehicle.)

We save the carpet for last so that we don’t have to worry about dripping on the carpeting while cleaning the other surfaces. Of course, it has already been brushed and vacuumed in Step 2 of the process above.
The basic process of cleaning carpeting is to first emulsify the soil, dirt, and stains in the carpeting. Second, we extract the emulsion in order to remove as much soil as possible. There are a couple of different versions of how to complete this “basic process:” the old way and the professional way.

The Old Way
The old-style method of carpet cleaning is to use a bucket of soapy water, a stiff brush, and a wet-dry vacuum. The technician would repeatedly dip the brush into the bucket and scrub the carpeting. Then, the technician would use the wet-dry vacuum in an attempt to suck out the emulsified soil and excess soapy water.

Since it is necessary to soak the carpeting in order to get it clean, it is difficult to get all of the soap solution back out. Even the most powerful vacuum cannot suck out all of this water. Moreover most wet-dry vacuums do not have the specialized extraction nozzle that a hot-water extractor has. The carpets are left overly damp and with soapy residue. A wet-dry vacuum cannot match the effectiveness of a hot-water extractor.

The Professional Way
Most professionals use a hot-water extractor to deep-clean carpeting because it is the best device we have to do so. An extractor consists of several components, including two tanks, a clean-water “solution” tank and a recovery tank (for the dirty water); a pump to transfer the clean water from the unit to the specialized nozzle; a heater to heat that water; and a vacuum to suck away the emulsified dirt. Why hot water? It will loosen the dirt from the carpeting much more effectively than cold water would. And the carpeting will dry faster if hot water is used.

A hot-water extractor heats the rinsing water. A good extractor delivers water at a temperature of 180-220 degrees Fahrenheit. A good extractor will also have a powerful vacuum system designed to remove as much moisture from the carpeting as possible. A unique aspect of a hot-water extractor is the design of the extractor nozzle, which combines a system that injects the carpeting with water with a specially designed vacuum nozzle that maximizes suction.

I recommend not using any cleaner in the solution tank. Instead, use only clean water. As such, the carpet cleaning
process is this: Spray the carpeting with a well-diluted solution of your carpet cleaning chemical, scrub with a stiff brush, and then use the extractor to rinse the carpeting. Essentially, the extractor becomes a device by which you can rinse the carpeting with hot water. This leaves little chemical in the carpet. Use only carpet cleaner that is specifically designed for use with an extractor. This chemical will be low-suds so that the recovery tank does not become choked with foam.

The carpets inside the car can be dried by using an air mover or using the vehicle’s climate control system. Turn on the fan to full, direct the flow to the floor vents, turn the temperature control to the hottest setting, and turn on the air conditioner, which removes moisture from the air.

Another very effective option for cleaning lightly soiled carpeting and mats is using a dry-vapor steam machine, which effectively cleans the surface of the carpeting without leaving it soaking wet.


Cleaning and protecting the interior of a vehicle requires expertise in the treatment of several types of surfaces. This subject will consequently be continued in an upcoming month.

Prentice St. Clair is president of Detail in Progress, a San Diego-based automotive reconditioning consulting firm. To contact him, e-mail or call (619) 701-1100.

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