From Henry to the modern factory finish

Since Henry Ford famously told customers they ‘could have any colour they like, as long as it’s black’, OEM paint finishes have evolved to deliver incredible gloss, durability and a vibrant rainbow of colours.

Back in the early 1900s, there was no such thing as automotive paint technology so early car makers had to make do with whatever was available. Made from natural oils, such as linseed or castor oil, these alkyd coatings were a carryover from the horse and cart era. As well as being brush applied and typically taking days to dry, they featured minimal gloss and durability.

1920s

Henry Ford had no particular affection for the colour black but when the founder of the Ford Motor Company discovered that the black paint, of the time, dried faster, it suited his fledgling production line process. However, cars still sat around for days waiting for the paint to dry and this didn’t fit with the efficiency goals Ford and other automotive trailblazers were searching for. It’s here that paint manufacturers began to develop the first automotive specific coatings. Typically based on cotton, they consisted of a nitrocellulose resin mixed with a solvent to create a low viscosity coating that also drove the development of the first spray guns. Drying time was slashed from days to hours and it eliminated brush marks for a better finish but durability was still poor.

Note: German spray equipment innovator, SATA, was already produced precision atomisers to deliver mouth and throat medicine, so when a leading paint maker came looking for a company to develop a spray gun to apply a new automotive paint, it was perfectly placed. SATA’s first spray gun was produced in 1925 and the rest is history.

1930s To 1950s

As automotive OEM paint technology developed, stoving alkyd enamels were introduced. ‘Stoving’ indicates that these coatings were high baked to achieve a faster drying time, along with a tougher finish, less prone to scratching. Having said that, in modern terms, stoving alkyd enamels were not particularly durable or glossy. On the plus side, colours slowly became more popular, essentially using the same system as today – finely ground colour pigments mixed into a resin medium.

1960s

For the first time we see hardener introduced, in conjunction with acrylic enamels which were baked at 140°C. The resulting chemical reaction created better adhesion and a cross-linked coating structure that produced a tougher, more durable final finish. Early metallic finishes also began to emerge. However, being Direct Gloss (DG) systems, the metallic particles were right through the coating, including on the surface where they would oxidise. What looked good in the showroom often didn’t translate to long term durability. One thing that did have a major impact on long term durability, by minimising corrosion, was the introduction of anodic electrocoat or ‘e-coat’. PPG became the first to successfully launch a cathodic e-coat system which is still used today. Unfortunately, some OEMs didn’t choose to add e-coat to their paint process until the 1980s!

1970s To 1980s

As more and more OEMs offered their customers the choice of metallic colours and finishes, we see the first Clear-Over-Base (COB) finishes arrive in the late 1970s. With a clearcoat layer to protect them, vehicle finishes offered much greater durability, particularly for metallics. As we rolled into the 80s, pearlescent mica colours began to become more common. At the same time, nonmetallic colours, such as white and red, often continued with DG technology but the pigments tended to suffer without a protective clearcoat layer.

1990s To 2000s

As environmental sustainability becomes a growing concern, OEM paint systems alter technologies to include the option of waterborne basecoat, as well as high solids solvent-borne coatings. Robotised electrostatic bell application began to take over around this time.

Using electrically charged droplets that are attracted to the substrate, they delivered superior transfer efficiency and finish quality.

2010 To Today

These days, more and more OEMs are taking advantage of compact paint systems, such as PPG’s B1:B2 and XP Basecoat technologies. Where a traditional OEM paint process starts with e-coat and a bake, followed by primer and a bake, and is finished with clearcoat and a bake, the compact paint system introduces a streamlined solution.

For example, the XP Basecoat process starts with e-coat and a bake but then applies a basecoat colour layer that includes primer properties, before adding a Wet-On-Wet clearcoat layer, followed by a final bake. As a result, an entire application and bake step is removed from the process which saves on time and the energy for the bake cycle, as well as requiring a smaller paint shop footprint.

Technology take up

As major steps have been taken in OEM paint technology over the years, you would think it would be a no brainer for vehicle manufacturers to update but it’s not that simple. Most new technologies necessitate at least a significant paint shop refit, while others need an entirely new paint shop. Therefore, a change of paint technology can easily require an investment of over $100 million and any advantages must be balanced against that. R