Paint Knowledge

I don't know much, but I do know BRG is the fastest colour:cornut:

Metallic paints tend to be a bit more forgiving when it comes to seeing swirls, but they are still there. But because of the flecks in metallic paint, they are harder to do paint touch-up.

From what I have gathered, MINI does not use the hardest of clear coats. So in my mind, this means 2 things. One, it will swirl/scratch easy. Two, it is easier to polish the defects out.

Richard has done a lot of research on paint, so I'm looking forward to his input.

Mark

 

I can tell you that any high metalic paint is a bear to match, the paint laid down on a repair will reflect light differently than what was put on at the factory, flat non metalic will always match better..

 

While I don't have experience on the factory assembly line for giving first hand experience on how MINIs are painted at the factory, I can offer some generalizations compared to the knowledge and experience I do have in the high end body shop business.

I think it would help to compare and contrast the way MINIs are painted at the factory versus repainting inside a body shop.

First off, when a MINI is painted, it's done by robots without all the interior pieces and fluids and drive train in place. This makes it possible to speed up the drying process by baking just the finish. Except for the R50/R53's, MINIs are now painted without primer. Essentially their base coat works like the primer. The speeds up the production line and reduces a step in the painting process. Paint thickness and hardness on the MINI is comparable to BMW and Porsche paint.

When a MINI is repainted inside a body shop, the car is fully assembled and full of flammable fluids and parts that can melt. Although the best paint jobs involve disassembling the car, it's not feasible to strip it down like at the factory, so drying the paint is done by air drying. Sometimes heaters are used to dry the paint, but they only go up to about the equivalent of a hot sunny day. The painters that work in body shops are a mixed bag. Some have a lot of experience with blending/feathering paint, some don't. Some know how to properly wetsand and buff fresh paint, some don't. What's important to know is that when a car is repainted at a body shop, the paint hardness is determined by how much hardener has been mixed in. If you've ever mixed two part epoxy together, it's similar. With paint, if you don't put enough hardener, the paint never dries. Put too much and you end up with very hard paint. Most body shops prefer to err on making the paint hard to avoid problems later.

Clear Coat paint is the same as the base coat except that it doesn't have pigment. There are some very expensive aftermarket clear coats, i.e. Glasurit, that produce phenomenal results with very little orange peel and are easy to polish, and there are very cheap paints that don't fully become clear after sanding and polishing and remain hazy and impossible to buff.

When buffing paint, maintaining acceptable levels of heat is key. Each material has a different threshold before the paint is compromised. Painted plastic bumpers will shrivel up and peel when heated up too much, whereas metal body panels at the same temps won't be affected. When polishing resins like carbon fiber, or even certain types of plastics, you can smell the material and it's very important to keep the temps low.

Remember that all modern paints have a clear coat. Some manufacturers will tint the clear coat to make the paint even richer. Lexus is known for this, but they also have some of the thickest paints. That's why when you polish black Lexus that often the pads will darken as though you were polishing paint without a clear coat.

Because the clear coat is the first thing that light hits, you want to make sure that it cannot obscure the color coat. Scratches, swirls, and defects will all bend light differently causing the paint to look washed out, faded, and dull. Through polishing, we can impact the color coat by simply removing the haze of defects that obscures it.

A polished car will be reflective, shine like a gemstone, and look more contrasty and rich than an unpolished car.

We can further impact this by tinting the clear coat with a barrier that effectively warms up the paint. This is what carnauba waxes do. Synthetic waxes traditionally don't warm up the paint. They provide superior durability, shine, and gloss without the richness and warmth of a carnauba. Prima Epic is one product that offers the richness of a carnauba with the durability of a synthetic.

Here is an extreme example of a clearcoat that has been wrecked and severely impacts the base coat.


And when restored


Before


After






This is an example of how rich Epic can make black paint look


Using a digital microscope, scratched paint looks like this


Through polishing we can remove microscopic amounts of paint


As the scratches get polished out only a few remain


The scratch has been greatly minimized so it's not even visible to the naked eye.



Using my earlier examples, of how a car is painted at the factory versus within a body shop, trying to touch up or match metallic paint is difficult because the flakes will never match the existing flakes, and this mismatch is what leads to dark/light patches in the paint. I've seen this on factory painted cars too, most noticeably on silver paint from all manufacturers.

This is why painters will try to feather/blend the new paint with the old paint by dusting the edges of the new paint into the existing paint to make it difficult to see where the new paint begins and ends. This is also why touching up metallic paints with a touchup pen/brush never gives perfect results unless the repair points are very small.

That's it for now!

Richard