Hi Mike, Posting over here, hopefully you can help. Thanks in advance

Need Help Color Sanding and Buffing – SPI Clear

Products Used:
Silver Metallic Base Coat
SPI –UV Clear Fresh- 1 week old, air dried, no bake
Norton Black Ice P1000, P1500, P2000 all wet by hand
Tried one piece of 3M Trizact 3000 wet by hand also on atest
M105 on 8” 3M Wool Compounding Pad05719 (recommended for Perfect-it step 1)
Makita 7”Grinder/Sander Variablespeed rotary. Running at slowspeed.Trying for about 1500 rpm
M205 on 8” yellow foam pad
5000K LED Tube lights in the booth. Look similar to a fluorescent tube

Hi All,
I am new to color sanding and buffing and need help. I am seeing what I believe are 2000 grit sanding scratch texture / pattern after I buff. M105 appears to round them and produce a nice shine, but does not flatten them.I expected flattening, not rounding and smoothing, maybe my expectations are off….

A little back ground. I have a 2001 F150 that I completely re built from the frame up.Sand blasted, painted every nook and cranny.(I am practicing for the classic63 caddy convertible I plan to rebuild). Cut out a lot of rust, welded in new metal (getting pretty good forming metal and tig welding).Did all the bodywork and painted myself. (My body work is as straight as an arrow, took me 30 years to learn to sand properly ). It is a silver metallic with 3 coats (about 4mils) of SPI UV Clear. Paint is a little over a week old at this point.
I had dirt, lint and fibers in it even after building a simple paint booth with filtered, pressurized air (surprised me, thought my booth would keep that out). So I decided to color sand to remove the dirt and orange peel.I started with 1000 grit wet and a E-7200 pad by hand, then 1500 and then 2000. Wet sanding by hand took a week..Whew.. Then used a wool pad on a rotary buffer and M105. With in 10 to 15 secs, a gloss develops and it looks good from a distance.
Picture of hood: Note that it was dark outside, so the reflection of the window is black.

However, on close inspection, I can see the “lay”/ “Grain”/“Texture” of the 2000 grit sanding scratch pattern. i.e, I can see the direction that it was sanded. I know it is the 2000 grit,because as a test, I sanded again in a different direction and rebuffed and the texture /grain / whatever, was in the new direction.I can only see it in the reflection of the LED tube light bulbs along the edges that are in the booth. Under any other light source, I have not been able to see it.
It is very difficult to take a picture of, but here is amagnified view (about 8X).. note thefuzzy angled lines (all angled the same way) along the periphery of the bulb.Notice that it is glossy, but the texture /pattern of the sanding marks are there. s

Here is another picture magnified (8X). I put a piece of blue tape near by to focus the camera.



So I guess my questions are:
1. I am newto buffing, I guess since the M105 is supposed to remove 1200 grit scratches, Iexpected it to completely remove these 2000 grit pattern marks.Do I need to use a more aggressive compound?Would M100 be a better choice?

2. Do I need to buff longer, I am buffing for about30 sec to 1 min until the compound dries and is wiped off by the pad.If you go any longer, it can leave a littleburn residue..I have re-buffed someareas 4 or five times and have not seen any real change in the scratchpattern.It seems like the first 20seconds does the trick and there is no more improvement after that.

3. Do I just not know how to buff?I have read a lot and can’t figure out what Iam doing wrong..Maybe I got the wrong wool pad or Compound?

4. I have also tried the M205 and the yellow foampad and not seen any real change in the gloss.I know it is supposed to remove swirls and buffer trails.Which I have not actually seen anyhow. But tried it anyways.

5. Do I need to sand with finer than 2000 gritbefore buffing?I did buy a sheet of the3M Trizact in 3000 grit and re-sanded by hand, an area that had been previously buffed inthe cross direction to the original scratch pattern and the resulting patternmay have been less, but I could still see the direction how the 3000 grit wassanded.

6. All my sanding is by hand, I am aware that if Isanded with a finishing DA, that the effect is that of using about 2 gradeshigher grit and the marks would be short and small and harder to see.Is that the problem, that I really need touse a DA?

7. Is my light source (5000K daylight LED) creatinga special situation where this pattern is visible when in the real world, itwould not be visible?

8. I have never actually looked this closely in a“SHOW CAR” finish.Would I see the samething?In other words is this normal?

9. In thinking about this, since compounding is a“free” abrasive, it does make sense that it would tend to smooth out thesanding scratches verse flatten them like a sanding block would..So maybe this is normal?And I am just looking too critically..

All comments and input are welcome…

Thanks and look forward to hearing from the professionals and amateurs alike.