Casting light with color.

Casting light with color.

"In this Special Series, I document my complete paint & body restoration along with the exterior upgrades to CSL specifications. 

In this entry, we've dusted away the sand from the never-ending sanding process, and we get to painting the shell and parts. 

But first, let's cast light with color: as naturally aspirated M cars age and decay, some of you will eventually cross the intersections I do in this restoration. 

I give you more insights into the paint process, how a paint shop makes or loses money - and where you should focus the budget!"

Casting light with color

Since I've started this Special Series, I've made it a point to cast light into the obscure world of custom paint & body. 

Here are the observations from years of experience:

  1. Most people don't understand automotive paint. 
  2. Most body shops make money from this information asymmetry

It's a dynamic that's most prevalent in the automotive industry: we see it with online parts sellers, at used car dealer lots, at detailers, mechanics and in paint shops.

My goal is to better inform and equip M owners of older generations that will eventually have to look into a respray.

Whether you do it like I did doesn't matter - I want you to know what it is you'll be paying for once you get to this complex crossroad in your E46 M3 ownership journey. 

[...] yet paint isn't just color.

When most M owners think of "paint" they think of color and clear coat. They often miss a step. 

If we define automotive paint by the actions of spraying durable coatings on your car, then it goes like this:

  1. Primer 
  2. Color
  3. Clear

The primer was actually 2 steps. 

1. Epoxy

It is used to seal in freshly stripped metal and protect it from corrosion. 

2. Build up

This a 2 component, catalyzed primer. It hardens to provide the surface tension required for block sanding techniques. 

The shell sits in the booth, with its primer sanded and ready for color. 

[...] and paint & body shops aren't all the same. 

There are 2 main categories of paint shops: 

  1. Production: 

    They primarily focus on insurance work. They optimize for quantity and speed. 

  2. Custom:

    They primarily focus on complete restorations and custom paint work. They optimize for quality. 

Custom paint & body shops are a world of their own. You'll find out very quickly there's always someone with more.

Their business model. 

Like most businesses, there are profit and cost centers. A body shop is made, or broken in the paint booth. As I cover the color paint process, I want you to keep two critical variables in mind at all times: 

1. In-booth and out-of-booth time. 

As a rule of thumb, in-booth is where time is most valuable as square footage is often limited. Money made becomes a function of time and space more so than out of the booth.

This dynamic is less impactful on a custom paint & body shop than a traditional production shop. 

There, you'll often find massive paint booths with nearly-perfectly sealed environments in production shops as they spray a lot more paint, a lot more often than custom shops. 

This small, simple paint booth isn't perfectly sealed - it doesn't have a chimney or massive vacuum effects, nor any sci-fi baking equipment. 

2. Cost of chemicals. 

As a rule of thumb, paint chemicals & materials get ever more expensive as you go through the actual paint process. 

There are a myriad of paint brands available. It's easy to get lost and brands purposely muddy the water. See my notes below. 

Notes on paint brands. 

For production shops. 

Most production shops will use one specific chemical brand usually optimized for speed: they want to use a little chemical as they can, and have the fastest drying times that they can. 

The reasoning is simple: booth time and chemicals are expensive.

Additionally, you need to cover the entire range of color codes available on the market, from all manufacturers. This has forced production paint shops to commit to one brand exclusively as they provide financing via a pay-per-use model on the rack.

The contracts can get complex. 

For custom shops. 

We use a mix of BASF automotive paint brands. They own various brands such as Glasurit, RM and Limco. BASF is headquartered in Germany and are a multi-national chemical company. 

ExclusivAutomotiv uses Limco for color: they are most cost friendly but take more coats to reach coverage. This allows him to focus the budget where it matters most: the clear coat. 

Along my journey, I have used various different paint brands such as PPG, HOK and various BASF lines to land his preferred mix. 

He furthered his craft by developing his own mixes of candy and translucide finishes. 

Anything is possible- just bring the checkbook. 

HIIT Sessions. 

Before we get into any sections about color being sprayed, it's important to know a car ever rarely gets sprayed in one go. 

It's just too complex. It's ever more so when it's a color change.   

The table below references time spent spraying, drying and in-between maximum waiting times spraying steps for the shell itself. 


 Timings per coat

Epoxy Primer 1 coat
30 minutes to spray 
60 minutes to dry
Build-up Primer

3 coats
15 minutes to spray
15 minutes to dry 

Sanding steps
Color Coats

3 to 4 coats (depending on color coverage)
20 minutes to spray
20 minutes to dry

Waiting Time 

Minimum 60 minutes to avoid strapping solvents and delaminating clear coat.

Clear Coats

4 coats 
20 minutes to spray
25 to 40 minutes to dry, increasing between coats. 

Shell first. 

You always start with the biggest component first: the shell. It will set the final color tone for every other spray session. 

With the shell fully primer'ed and sanded, it got masked and taped ready for color. and clear.   

Color coats are sprayed until full color coverage is reached. Colors dry fast. I didn't get there in time to snap pictures before the clear coat.

The clear coat is immediately applied a few hours later to seal in the color. 

The 4 coats of clear create a much thicker unified clear coat than OEM applied clear.

This creates further orange peel and traps dust specs along the way. We'll explain why that is in later entries. 

The Karbonius CSL roof was also recleared entirely. This is where the paint line ends. 

We know about the last dabs of yellow. Don't worry about it, trust the process. 

Parts second. 

The body panels such as fenders, hood, bumpers and diffusers were sprayed in another session. I managed to get there on time and catch the color coats drying.

You'll notice they are satin finish. This would be considered single stage paint to most. The lack of clear coats exposes the color to UV, chemical and abrasion damages. 

The 1:1 CSL carbon bumper shows of its curvatures. 

The widened carbon fenders are looking meaty. 

The side skirts were sprayed alongside the hood, fender and front bumper. 

The hood's underside also got sprayed. This requires another session for the topside. 

I had to run and couldn't catch the clear coat application in real time. I dropped by a few days later and voila!

I pulled out a fender to marvel at it under bright LED lights. 

Dust specs and orange peel. That's what 4 coats of clear will do. Trust the process. 

More parts later on. 

A car has many parts - more at 11! 

The carbon diffuser got sanded down. Masking the paint to carbon line will be interesting. 

The CSL carbon trunk required some fitment and trimming work first. 

A color change is complex and presents many cross roads and opportunities for unique twists. 

With prior experiences of future steps, I know how this will look when we're done with finishing steps.

Visualizing it coming together is half the joy, the process is the other half. 

Up next: we get to the underbody, switch up the original plans and pay hommage to PY. 


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