Analysis: Sanding vs. Velvet Pad Compounding to reduce orange peel. Which removes more paint?

This question has been always on my mind ever since I have been introduced  reducing orange peel via velvet pad compounding.

I took my new test panel which has a fresh coat of paint and taped it in half. I then took 25 readings on each side.

On the left, I used the following to reduce the orange peel:

1) Osren P40 Compound, Osren Velvet Pad, Makita 9227C @ ~1200 rpm
2) Meguiar’s #105 Ultra Cut Compound, Lake Country Purple Foamed Wool, Makita 9227C @ ~1200 rpm
3) Meguiar’s #205 Ultra Finishing Polish, Lake Country White Polishing Pad, Makita 9227C @ ~900 rpm

I was familiar with this process and got it almost perfect in less than 15 minutes.
On the other hand, I am totally unfamiliar with colour sanding to remove orange peel as you will see below.

First pass hand of sanding with 2000 grit sandpaper

Second pass of hand sanding with 200 grit sandpaper

I got impatient and took out the DA and a Sia 1000 grit foam sanding disc.

Now that ought to flatten the paint out nicely

Followed with Mirka Abralon 2000 grit

Compound with M105 and wool pad, followed by M105 and white polishing pad

Tape removed

Whole bonnet is DA-ed with M205 and black finishing pad to remove holograms.

Looks good from afar

Recording the readings

Sonax paint prepare was used to remove all oils and silicones in preparation for coating

Sonax profiline nano paint protect is used. Reason for this is to see if it would build back the microns with additional layers (future testing).

Now let’s take a closer look at the results.

Before, lots of dust nibs, and orange peel.

After sanding, is that orange peel?

After velvet pad, not the flattest paint, but at a satisfactory level

So velvet pad flattens better than sanding?? Hold up son, this doesn’t make sense, the 1000 grit foam sanding disc completely hazed up the paint, removing any ‘highs’ in the paint, then why does it still look ‘orange peely’?

Let’s zoom in further. All images are clickable for higher resolution.

Before

After sanding

As seen in the photo above, the orange peel texture of the paint isn’t actually orange peel, but are DA sanding marks, probably caused by the 1000 grit foam disc, and were not fully removed during the compounding with wool pad. Remember, this is aftermarket paint, which is harder than the average factory paint.

After velvet pad

Results after the velvet pad looks great doesn’t it? Why don’t all of us just ditch sanding and use velvet pads instead then? Seems too good to be true and there must be some kind of trade off.
Here’s where the paint thickness measurements will come to shine some light.

I compiled them into Excel and made 2 charts.

Blue areas indicate thickness before flattening, red areas indicate thickness after flattening.

Average paint removed via sanding : 2.912 microns
Average paint removed via velvet pad: 3.148 microns

From the two figures above, we can conclude that the difference is negligible, or is it really?
Do recall that I sanded the paint with 1000 grit foam disc, which completely hazed up the paint, this is aggressive sanding and even after that, average paint removed is still LESS than velvet pad.

Velvet pad is easier and faster, but with the trade off of marginally higher paint removal.
Granted that the sanded area still had pigtails and needed heavy compounding to remove, which may bring the average paint removed figure closer to the velvet pad’s or even higher.

The point is, sanding with 1000 grit still removed less paint than velvet pad compounding! This is pretty astonishing, I was hoping that velvet could remove less while flattening the paint, guess it has it’s ugly side too.

What’s even weird is that 1000 grit sanding only removed 3 microns of paint? This must show that the paint is pretty hard.

What about soft paints?

I tested velvet pad compounding on a rear quarter on a black Honda CRZ. The paint was super super super soft (seriously), polishes just turn gummy and sticky when used with a machine polisher.

Heavy orange peel

Velvet pad and P40 compound literally destroyed the paint!

After the follow up steps and wipedown with Sonax Paint Prepare, as you can see, there is still some hazing which is quite impossible to finish down, unless a glazing polish is used.

Orange peel before

Orange peel after, ~50% removed

Now I did not systematically record down the readings but all of the ‘before’ readings were around 110 microns.

The ‘after’ readings dropped to as low as 90 microns.

A range of 10-20 microns was removed from this soft Honda paint!!
Compare that to only 3 microns to the hard aftermarket paint. Makes you just want to sue Honda just for using such soft paints.

So, what can we conclude from this analysis?

Sanding is like using sniper to hit your target, precise and accurate but time consuming as you can only shoot one target at a time. i.e., more care is needed and follow up compounding may take longer time.

Velvet pad compounding is akin to using a bazooka to hit your target, fast and effective, but with collateral damage. i.e., relatively more paint removal.

So after knowing this, would I ditch velvet pad compounding to flatten paint? Definitely not, this is effective and fast, paint removal may be higher, but only 1-2 microns more on hard paints. I would definitely use this combination on hard paints, such as those on CBU BMW and Mercedes cars. Keep in mind that locally assembled cars are painted here and have medium hardness paints, not the same as their imported brothers.
What about soft paints? Further testing is needed as I have not attempted to sand and compound soft paint before, I might try it on the other rear quarter panel of the black CRZ, but also afraid to over sand and cut through the clear.
I wonder how much paint did I remove when I reduced the orange peel on the Subaru Impreza:

https://wetshine.net/2011/07/22/subaru-impreza-beyond-swirl-free/

If only I had a paint thickness gauge then.

Feel free to leave your opinions and comments on this subject, thanks again!
Will be doing an intermediate detail on an M6 this weekend, follow me on Facebook for quick updates before the full write-up goes up.