Not An Ordinary Paint Job
Step 1. Phosphate Bath
Your BMW is immersed in a bath of phosphate, zinc, manganese, and nickel, then removed. The chemicals form a protective crystalline coat that aids in the corrosion-protection process. It’s the first of several layers of protective coating that will be applied to your BMW body.
Step 2. E-Coat: The Paint that can’t be seen
To ensure each body is completely protected, BMW employs a process known as electro-coating, or e-coat. Using an overhead guidance system, the body is lowered into a specialized pigment solution. The body is electrically grounded and the pigment solution receives an electrical charge. When the opposing charges attract, they form electronic bonds at the subatomic level. The process produces a complete and uniform coat that ensures every nanometer is covered, no matter how complex the body. It also provides a bonding layer that ensures superior adhesion during the subsequent painting process.
The body emerges from the e-coat and is sent to the first of four drying ovens. After 40 minutes at 340 F, the chemicals in the e-coat have completely cured and the body is transported to the sealer deck.
Step 3. Sealer Deck: Protects vital parts. Protects performance, too
Most of the hundred of crevices and cavities of a BMW body are too small to be seen by the naked eye, yet big enough to be exploited by moisture, salt, and corrosion…and even sound. On the Sealer Deck, we ensure that doesn’t happen. Here, associates and gun-wielding robots deposit a high-pressure, high-density sealant into almost every welded joint. As the bead seams cure, they create a waterproof barrier that also eliminates exterior moisture. At the same time, the bead seal never interferes with the aerodynamics of the body. The flow rate is regulated to inject a bead that is flush with the surface of the vehicle. Yes, we’ve thought of almost everything.
Step 4. Underbody Sealer: 540 degree of protection
A BMW is designed to outlast most anything Mother Nature can throw in its path, even when moisture kicking up from the road drenches the underbody. That’s why we take as much time sealing underneath the vehicle as the rest of the body. Robots, using specially formulated polyvinyl chloride and pneumatic sprayers, seal the entire underbody and floor pan, paying special attention to where it joins the side panels. This not only keeps your feet dry, it reduces outside noise.
Step 5. Pre-Paint Inspection: An ounce of prevention
Once the car enters the paint booth, there is no turning back. So during the pre-paint inspection, we go to extraordinary lengths to ensure the body is as pristine as it is perfectly formed. Associates examine the e-coat, bead seams and underbody sealer, looking for dirt, residue, dust, and the tiniest imperfections in the metal. To ensure a perfectly clean surface, associates work every panel and contour with ultra-fine grit orbital sanders and hand held pads. After a final check, associates add sound-deadening pads to the trunk and passenger areas to further ensure the ultimate quiet ride.
Step 6. Primer Booth: Dustless = Flawless
A single strand of stray lint, less than 10 microns in diameter embedded in the primer coat is all that’s needed to ruin the most expensive paint job. We make sure that never happens. From the moment it enters the Primer Booth to the minute it exits the final paint inspection, the BMW body remains in a sterile and controlled environment. Associates working inside the Primer Booth must pass through a special air shower. The ventilation system inside the Primer Booth continually filters the air, trapping tiny particles. Prior to priming, associates hand wipe all surfaces with lint-free cloths and perform a final dusting using ostrich feathers. Robots then use pneumatic sprayers to apply one of 13 primer colors in a uniform coat on all interior and exterior surfaces. Forty minutes in the oven and the primed body is nearly ready to be painted.
Step 7. Inspection and Basecoat: Still no substitute for the human eye
At this level of detail, subtle variances in primer surface and other inconsistencies can only be detected by a sharp eye and soft hand. On the inspection deck, associates perform a hand/eye inspection to catch any defects, then use detailing sanders and hand blocks to carefully remove any inconsistencies in the primer coat. The body is wiped clean with a high-tack, lint-free cloth and enters the Basecoat Booth. Inside, one of 19 paint colors unique to BMW is electrostatically applied to the interior and exterior. Electrostatically applied paint is a high tech process involving negatively charged paint particles that are electrically drawn to the surface of the BMW, reducing overspray.
Step 8. Clear Coat: Inner beauty reflected
By definition, a car’s shine and its color are distinctly different optical properties, which cannot be maximized with a single solution. So we treat them separately. During base coating, the body receives its deep rich color. In the clear coat process, robots apply a clear, high-resin paint that, when dry, reflects a majority of directed light. In other words, it shines.
As the body exits the clear coat booth and enters the last and largest of BMW’s four drying ovens, it takes on another significant advantage. The high resin content gives the higher density, which provides greater protection against oxidation. These same characteristics also add UV protection, helping to prevent the sun’s rays from fading the paint.
Step 9. Cavity Wax: No crevice, no seam left unfilled
In the final corrosion-protection process, associates use water-based paraffin wax to prevent water from getting into the smallest crack or crevice. Associates inject the melted wax into all body cavities, completely coating the cavity. Gently rocking the body allows the wax to seep into the tiny crevices and seams. Once in place, the wax quickly dries into a hard, naturally protective coating. From here the finished, painted, and sealed body is conveyed overhead to the stacker to wait its turn for Assembly.
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