Step-By-Step Sanding & Compounding BMW

[Totoland Mach]

Okay Auto Geeker's: I decided to chronicle a start-to-finish job on a BMW 745 Li.... I'll update the thread as I complete a task. I thought I'd go ahead with Sanding-Compounding-Glazing the hood as a start. Typically, I sand hood and trunk if there are imperfections (scratches and stone chips) and this one was no different. The sides and roof will get compounded later, so here we go:

I had a great teacher with the shop owner: He's been a BMW dealer and worked on cars most of his adult life. He's taught me a bunch about "reconditioning" a car as opposed to the driveway detailing I've been used to. We try to bring a late model Bimmer back to "as new" condition both exterior and interior. I spend a lot more hours doing these steps, but the results are always consistent: excellent and ready for sale.

Here's the tools I started with: Snap-On orbital air sander, and 3M 3000 Grit Trizact pads. I use a cheap deail spray as a lube for the 3000 grit.


Next: I got a shot of the Shop owner showing me how much to sand on a finish (I was not taking it down enough previously).


Here's a pic of the hood showing the effects of sanding. I removed more material where there were scratches, as you'll see in another pic.


Here's where you can see different levels of sanding. The center of the hood had some decent scratches and the 3000 leveled the paint. Looks kinda scary at this point!


Another hood shot highlighting the front portion that was sanded.


The area near the headlights had several rock chips (as most road cars do). The sanding saved me tons of time because I would have to try to fill these in with touch-up paint.


Compounding (used Optimum and 3M because we have a lot of both). Compounding is slow and steady! DeWalt Rotary on 1200 and keep working an area until any sanding haziness disappears. Compounding is really the foundation for the rest of the car's finish look. Glaze and wax are really going to show and protect what you've done in the compounding step.


Now you can start to see what compounding can accomplish


Glazing: I kept the rotary at 1200 and worked a small area at a time until the glaze had the desired appearance.


Done! Compounded and Glazed. I'll sand/compound/glaze the trunk lid and compound/glaze the rest of the body panels in the next few nights.


The hood finished flawless! After the rest of the car is complete, I'll put a coat of wax on it, then power wash the body to remove product from body seams and other areas.


I hope this gives others an idea of where to take sanding and compounding. I'm very fortunate to be in a shop environment as this work would be a "bear" in any other situation.

I'll post more as I come to a specific area (including the interior).

Toto

[Kelso]

awesome info, much appreciated

[Larry A]

Yes ! continue, Id like to see more.

[Flyboy]

are the rock chips gone now as well?

[ryandamartini]

A few questions.

So depending on the severity of scratches, what grit paper would you normally use ?

Also how many OPM is that snap on air sander? Do you apply pressure like a PC? Lighter? Heavier ?

[Whitethunder46]

So when your wetsanding, do you almost always use 3000 grit?
Are you only sanding the clear or actually through the clear and some of the paint itself?

[Totoland Mach]

Flyboy: The small, light chips are gone. The heavier ones are minimized so it will only take a small amount of touch-up paint (which is always a pain on metallic cars)

Ryan: I use 3000 grit with the orbital sander. I have other, more aggressive pads (2000, 1500, 1000), but I haven't used them at all. I don't have the specs for the OPM of the Snap-On, but I'd equate it with a pc on 4-5. Yes, I apply pressure like a pc. One of my problems (intimidation factor of 9.5) was I wasn't applying enough pressure. I found out from my "teacher" to use more pressure. The Snap-On is 1/10 the weight of the pc...it's that light in weight. Also, the 3000 grit does not last long. I could use one pad for just the hood if it was bad enough. My teach said most pro detailers use 2-3 pads for a job. And they are expensive!

Whitethunder: At this point, I only use 3000. As I learn more, and a need comes up, I'll have him show me the stronger grits.

Yes, I'm only sanding the clear. That white residue you see under the sander is clear coat. He also has a paint meter for measuring and uses it when he first gets the car. This is because someone else may have sanded the car previously and it wouldn't take too much to go right through the clear to the color coat.

Hope that answers questions.

Toto

[Truls]

Nice job Toto, just want mooooore. keep up the posting, loving it

Sanding is not a beginners task, so its nice to have someone like the owner to watch your back while working on the car. You learn......we learn.

When someone who knows what their doing do something, it always looks so easy when its being done . they call em "the pros"

[Kelso]

do you ever wetsand to remove heavy orange peel?

[Totoland Mach]

do you ever wetsand to remove heavy orange peel?

No, but it would be the same process. I've got some orange peel on the back of my Mach 1's trunk lid. I might try to remove it this winter during some slack time.

Toto