2000 grit leaving score marks

[waqasr]

Hi guys new here but not new to detailing. I painted a replacement wing for my car and finished with 2k clear coat. let it dry for 5 days and then removed the orange peel with 2000 grit 3m paper, there wasnt much peel so didnt take long. I brought the gloss back with M101 and LC purple wool and finished with carpro reflect on a finishing pad and the finish looks perfect.

However look real close at the right angle and I can see tiny score lines the 2000 grit left, these are not tracers. My confusion is that M101 and wool should easily remove 2000 grit marks, which it did....but also didnt lol.
Now im not in the bodyshop or detailing trade, these are just hobbies so it could be something to do with the paint but I doubt that as temperature and humidity were fine, paint was mixed to spec and sprayed as per tech sheet.

Also to note im doing hand sanding, no DA sanding. I did follow up with 2500, 3000 and 5000 which gave a perfect finish but I thought just doing 2000 to save time would work out but just not happy about the score lines.

IMG-20170928-WA0001 by joe blogggs, on Flickr


20170928_123958 by joe blogggs, on Flickr


20170928_124119 by joe blogggs, on Flickr


20170928_154054 by joe blogggs, on Flickr

As you can see these arnt glass like reflections. I did do my old cars factory paint bonnet upto 3000 and it came out like glass. I didnt think leaving out 3k would make that big of a difference and really I thought M101 and wool should be able to remove 2k grit marks. Have I got a dodgy batch of papers or do I need to stop being lazy and sand up the grits to 3000?
20130717_190942_zps2ed8037a by joe blogggs, on Flickr

 

[DaveT435]

What kind of machine were you using? I'm sure a rotary with wool would have taken the 2000 grit sanding marks out. I've never used a DA with wool so really not sure if that would or not.

 

[waqasr]

Using a rotary pal. I gave it a good few hits and the marks just were not budging, not sure what to make of it to be honest.

 

[Strong66]

What was your process for painting, did it involve a high build primer or a heavy coat of sealer, either of those not given enough time to fully cure

could cause shrinkage, leaving sanding marks from whatever grit that was used under them.

Do the sanding marks look more coarse than 2000 grit?

 

[waqasr]

1 coat of 2k primer, dried for 3 days. Wetsanded primer with 800 grit. Then base till even coverage and then 1.5 coats of 2k clear.

Its definitly not shrinkage. The sanding marks dont look more course either, they are from the 2000.

 

[Strong66]

Definitely strange, I have never had a problem getting 2000 grit marks out, even using a foam polishing pad and polish.

I would try wet sanding it with some 3000 Trizact and hitting a polish if you have any on hand.

 

[mwoywod]

What was your rpm range? Which wool pad? Removing 2000grit block/hand sanding marks does tend to take more work than removing 2000 machine sanding marks.

If your RPM's were higher than 1,400rpms, IME, the lubricating oils in M101 will dry up too quick which results in more friction and more heat.

I assume the dye back of sanding marks is likely due to the heat induced and the subsequent paint swell.

Like others have suggested, wet-sand with Trizact 3000 or Mirka Abralon 3000 then try again with machine speeds between 800-1300rpms.

Make sure your wool pad is CLEAN. Spent compound and paint residue will not only interfere with finishing ability of abrasives, it'll also interfere with cutting ability.

good luck!

 

[Mantilgh]

Maybe it’s under the paint?

Maybe the paint did not conceal sanding marks from your panel prepping if you did some sanding.

It’s is really hard to tell from the pics.

 

[mwoywod]

Maybe it’s under the paint?

Maybe the paint did not conceal sanding marks from your panel prepping if you did some sanding.

It’s is really hard to tell from the pics.

I agree. From the pictures it definitely looks like the 800grit sanding marks used during the panel prep.

 

[waqasr]

What was your rpm range? Which wool pad? Removing 2000grit block/hand sanding marks does tend to take more work than removing 2000 machine sanding marks.

If your RPM's were higher than 1,400rpms, IME, the lubricating oils in M101 will dry up too quick which results in more friction and more heat.

I assume the dye back of sanding marks is likely due to the heat induced and the subsequent paint swell.

Like others have suggested, wet-sand with Trizact 3000 or Mirka Abralon 3000 then try again with machine speeds between 800-1300rpms.

Make sure your wool pad is CLEAN. Spent compound and paint residue will not only interfere with finishing ability of abrasives, it'll also interfere with cutting ability.

good luck!

Lake Country Purple foamed wool, quite an aggressive pad. 1000-1200rpm, really trying to keep it lower down in speed to keep heat down.. Panel was only mildly warm after a set. I would like to try Trizact disc but, 1) they are really expensive here and 2) I Dont have a DA. I make sure to clean my pads after every polishing set.

Maybe it’s under the paint?

Maybe the paint did not conceal sanding marks from your panel prepping if you did some sanding.

It’s is really hard to tell from the pics.

Im certain its not under the paint. Ill do another test section today and try to get a picture for you guys with better pictures, unfortunately I only have my camera phone.

I agree. From the pictures it definitely looks like the 800grit sanding marks used during the panel prep.

Its not under the clear. Basecoat will cover 800 scratches easily and its quite a few coats of base as this colour didnt have good covering power. Correct flash off wait times between coats and all that so no issues there. Like I sad Ill do another test patch here and try to get better pictures.