engine and drivetrain Original Underhood Finish

[Kile Brekke]

Short form:
Is the underside of the hood supposed to be glossy or dull? 

 

Some context:  

I just had a spare Inka orange hood freshly painted to Pastellblau. 

Since I did not want any trace of Inka, I had them paint the underside as well as the removed  torsion bar.

 

The shop did an awesome job with the match and the polish on the outside, however they deliberately did not clearcoat the underside with a glossy sheen that matches the outside. 

They told me the original finishes were more of a dull flat finish. Which to me, seems harder to clean when my engine will inevitably decide to spray oil all over it.

 

Is this true, or were they cutting corners? I have all the new weather stripping, insulation pads, and even new fuse decals to get this back together, but I will regret moving forward if this needs further finishing. It sounds menial and petty, but I only want to do this once.

 

Thanks in advance

 

 

 

 

 

 

 

[Conserv]

Glossy.

On '02s, the underside of the hood originally received the same finish as the exterior. Non-metallic paints, such as Inka, were strictly single-stage (no clear coat) whereas the disastrous metallic paints were dual-stage. Even in the engine compartments, the dual-stage metallic paints received their clear coat.

Echoing your concern, I thought that dual-stage paint NEEDED to be clear coated if it was intended to last any length of time.

Regards,

Steve

Edited January 22, 2016 by Conserv

[Mark92131]

On '02s, the underside of the hood originally received the same finish as the exterior. Non-metallic paints, such as Inka, were strictly single-stage (no clear coat) whereas the disastrous metallic paints were dual-stage. Even in the engine compartments, the dual-stage metallic paints received their clear coat.

Echoing your concern, I thought that dual-stage paint NEEDED to be clear coated if it was intended to last any length of time.

Regards,

Steve

 

 

So, his non-Metallic PastelBlau paint should be single-stage and not have a clear coat?

 

Mark92131

[Conserv]

So, his non-Metallic PastelBlau paint should be single-stage and not have a clear coat?

Mark92131

Not exactly, Mark. I believe I've short-cutted the explanation! His Pastelblau underhood should have gloss to it, however that is achieved. If you're using dual-stage paint -- which requires a clear coat -- then it should have a clear coat.

In 1974, Pastelblau would have been a single-stage paint. The gloss didn't rely on a clear coat; it was inherent in the color coat itself. But today dual-stage is far more common for all re-paints. So you'll need a clear coat for gloss.

This is one of the great controversies of old car restoration: do you use single-stage because that is what was used originally? Or do you use dual-stage because that is what most body shops would like to use today, and it does appear to hold up spectacularly?

Regards,

Steve

Edited January 22, 2016 by Conserv

[Conserv]

Nearly 40 years in, the underside of my '76's hood has lost much of it's clear coat and gloss -- Polaris metallic so it was dual-stage paint from the outset -- but around the front and sides of the hood, where it was more protected from weather and the engine, some gloss remains. The underside of the luggage compartment lid was also finished in the same full-gloss finish but, without an engine in there or exposure to much weather, it has held up very well.

The third photo below, taken in August 1983, shows my '76's hood in younger days, albeit 7 years old. The light variations on that left-side box member are from daylight "playing" on the glossy surface!

Regards,

Steve

Edited January 22, 2016 by Conserv

[LJtii]

This is the underside of my '73 Malaga with its factory finish intact. There is no difference in the quality of the shine vs. the exterior paint.

[Kile Brekke]

Awesome. 

Thanks guys, I have my answer. 

 

Gloss it is. Looks like I have a bone to pick. 

[Beemeup]

To my eye, single stage achieves the "right" look. The depth and the tones when viewed from different angles is quite apparent between the 2 systems. I get why collision shops use 2-stage systems, but it's the wrong application for cars that came with single stage paints, IMHO. It's worse than having a snorkel on a Tii in my opinion.....! :-)

[Kile Brekke]

I could be mistaken— But in CA, at least, I think shops are somewhat limited with what they can spray, no?

I think that the 2 part base/clear water-based systems are what they are pressured to use?

[LJtii]

Yes, but they achieve a nice, glossy finish with them. To tell an owner the under side of the hood on a 2002 should be a dull, flat finish is simply incorrect.

[Kile Brekke]

Yes, but they achieve a nice, glossy finish with them. To tell an owner the under side of the hood on a 2002 should be a dull, flat finish is simply incorrect.

Agreed— 

Which is why this thread is "answered" and I will address the concern with the shop. 

 

Your photo was very helpful. Are those insulation pads original as well? They look much different than the other rectangular pads. 

[Redtail]

Out of curiosity, what was the problem with the metallic paints from the factory? I have a sahara car (actually both my 2002's were sahara - the least loved color of all) so I don't know the details of the metallic paints.

[rstclark]

My understanding is the 2 stage paint with a clear top  is much more durable than an old fashioned single stage enamel.. For my money if you are going to the trouble of a complete paint job and especially a color change, why use a inferior product.  9 out of 10 people cant tell the difference

[Conserv]

Out of curiosity, what was the problem with the metallic paints from the factory? I have a sahara car (actually both my 2002's were sahara - the least loved color of all) so I don't know the details of the metallic paints.

Dual-stage paint was new technology at that point in history, at least to BMW. So the clear and base coats would fail, and fall off -- which is a problem. At the time, there was a lot of talk about the clear and base coats expanding and contracting at differential rates, but no official explanation was ever provided by BMW and I honestly don't know the cause.

BMW, at least for the U.S. market, developed a general approach to resolving these issues: if your paint failed within 3 years, they'd foot the bill; if it failed after 3 years, you were SOL. It seemed that horizontal surfaces, e.g., hoods, roofs, and trunk lids, failed most quickly and thoroughly, so some cars were repainted from the belt line moulding up. There were at least 5 versions of Polaris-metallic made, attempts to re-formulate the paint to resolve the problem. None worked. The Polaris paint on my '76, for which I had paid an additional $244 -- maybe the equivalent of a $1,500 option today -- failed after 4 years, so I was SOL. But my car was always garaged and lavished with care, whereas a friend's father's car failed after only 2 years, probably because it was not garaged. I harbored sufficient resentment over this issue that it was 2010 before I purchased another BMW. So, yes, the metallic paints were a problem!

Regards,

Steve

Edited January 23, 2016 by Conserv

[LJtii]

Your photo was very helpful. Are those insulation pads original as well? They look much different than the other rectangular pads. 

 

I have no reason to believe they are anything but the original pads. There is no evidence of anything having been there before them, and they are made of a rough texture unlike any of the repro pads being offered today.