August 28, 2007

Why Do People Paint Carbon Fiber?

From: William Jon Shipley
To: Zachary Edson [Tesla Motors]
Subject: Carbon fiber without paint?

Is there a technical reason that Teslas are painted? I'd really rather not have the extra weight, expense, and scratch-ability of paint on my carbon fiber.

Does carbon fiber look bad on its own? I think I heard [Dr. Eberhard] say something at TED about it needing a thin shiny coating on it to look good.

I'm remembering the unpainted DeLorean, and how everyone made fun of it at first, and now it's considered a classic beauty.

Frankly, I think if you're going to have a carbon-fiber body, you should show it off.


From: Zachary Edson
Subject: RE: Carbon fiber without paint?
To: William Jon Shipley


There are a few issues involved with carbon fiber. I think the best way to highlight them is in a bulleted list:

- Unpainted carbon fiber is not particularly aerodynamic. Aerodynamics becomes very important to efficiency on the freeway.
- If you look at an unpainted carbon fiber body panel that has not been [treated in any way] it is not particularly attractive.
- If you want a piece of carbon fiber to look attractive when not painted it costs about 30 times more than an unattractive piece of carbon fiber.
- Once you have the piece of attractive carbon you need to seal it and clear coat it for it to be both aerodynamic and attractive.

In the end it is far lighter to use painted carbon fiber than to use unpainted metal. Very few cars have been built with exposed carbon body panels. The ones I know of were built one off for a customer with no disclosed price.

I agree that it would look great to have an exposed carbon surface on the Roadster. The cost would just be astronomical and there would not really be any gain in overall weight.