When do you put down the polisher and pick up the sander?

[Matt@Revive]

i am working on a 2013 Mustang that has lived as a rental car and seen 2 lifetimes of automatic car washes. i did a few test spots and found M105 on a MF cutting pad will remove the defects after about 2 applications of 4 sections passes on speed 6.

after spending nearly 6 hours compunding and polishing the roof and hood, i'm looking at the trunk and both sides of the car and wondering if it would be faster to hit the car with 3000 grit before compounding.

[Setec Astronomy]

What machine are you using?

And are you contemplating sanding by hand or machine?

[Tato]

Wow, that's nasty.

I'll comment 'outside' the sander subject, and let's hear our friend's opinion towards sanding procedures to recommend you.

Please, do not read my words bellow as the right / best or only way to do it, just some thoughts to help you deciding what's better for YOU.

From how you described what you're facing

"...and found M105 on a MF cutting pad will remove the defects after about 2 applications of 4 sections passes on speed 6. "

I'd do the following:

a) Grab a heavier cutting compound like Meguiar's M100 or Menzerna SHC300.

For me there's a sign M105 is not working it's full potential in this paint (can happen, not all products will work 101%, 101% of time).

I did a Golf 2013 (link bellow) where FG400 and MF wasn't enough, just stepping up the compound to M100 did the trick. That date I haven't got SHC300 yet.
2013 VW GOLF Sportline - 'Revival' + Pinnacle Black Label Coatings

M100 and Meguiar's MF disc is not an 'invention of mine', M100 came with my Meguiar's Microfiber 5" Kit. Glad they did it.

After stepping up compound I'd do a complementary compounding step - in my case FG400 on orange foam cutting pad (you can use M105).

This secondary compounding step will be gentler than the first, although it's still a powerful combination and will improve the finish towards finishing the job.

In some cases FG400 and orange pad can meet LSP-ready this time, although the final finishing step takes so little time it's almost always worth doing to guarantee the best results. Again, depends on test spot, $$, time, there's no rule.

Lastly, the third step would be a white polishing pad (or black/gray depending on test spot) with your favorite finishing polish (mine is SF4000), you can use M205.

This should be a way to workaround when you need an extensive compounding procedure but want to keep moving towards finishing without deviating from 3-steps at maximum.

Again, just some thoughts, hope that helps.

Kind Regards.

[Mike Phillips]

When do you put down the polisher and pick up the sander?

After you've read this article,

Wetsanding - Fresh Paint vs Factory Paint

[Mike Phillips]

after spending nearly 6 hours compounding and polishing the roof and hood, I'm looking at the trunk and both sides of the car and wondering if it would be faster to hit the car with 3000 grit before compounding.

One thing for sure....

Sanding a car is easy.... getting 100% of the sanding marks out is the tricky part....


(You can quote me on that)


Seriously, it would be faster and cooler to the paint to machine sand it with #3000 or #5000 and then remove your sanding marks using a compound and a rotary buffer.

You can do it using other tools but it will take longer and the other tools will never be as powerful and thus effective as a rotary buffer.


If this is a daily driver, I would keep this point in perspective and hit it with either a Flex 3401 or a rotary buffer for your first step and then simply clean it up with a follow up step and polish.


This was a three step process and it has a LOT of swirls and scratches and I found the paint to be on the medium to hard side.


We used including these three steps...

Step 1 - Compounding the paint using Wolfgang Uber Compound on a wool pad with the Flex PE14

Step 2 - Polishing the paint with a black Hybrid finishing pad on the Flex 3401

Step 3 - Machine waxing with Wolfgang Fuzion.

Mark's Fast Ferrari with Wolfgang Fuzion

[Matt@Revive]

What machine are you using?

And are you contemplating sanding by hand or machine?

I'm using a Rupes 15. i was thinking about machine sanding with my PC using and interface pad and unigrit 3000

[Tato]

An addition, here's from where I got the the 'dual-compounding'-step

Microfiber first cut:


Foam cutting pad secondary cut:


And the recommendation for the last step:
"... The next step if this were a car would be to re-polish using a less aggressive foam pad and polish and then seal the paint."

All the Pictures above are credited to Mike Phillips, found in the bellow thread:
http://www.autogeekonline.net/forum/...-compound.html

Coincidently, this approach was used after a sanding procedure, so I recommend you to take a look at this thread as well:
http://www.autogeekonline.net/forum/...ing-discs.html

Not exactly what you're looking for, but great source of info.

Kind Regards.

[expdetailing]

Matt, I've used the Unigrit disks before and found it was time consuming as well. As a beginner, you'll need to move slow and careful so that you don't get eaten by the learning curve.

[dlc95]

Have you tried slowing the speed down? Maybe try the pc?

I've had much success with m105/Rupes blue mf disc/pc7424xp removing 1000 grit sanding marks on a scrap Honda door. I primarily used speeds 4-4.5. Light to moderate pressure. Maybe it's worth a try?

[dan989]

Please answer so I can help you, I have been at this very same place 1000 times…I hope this doesn’t sound derogatory in any way.
What is the customer paying? Or what results is the customer expecting to see? What level of exterior detail did you sell him/her? What is your skill level of sanding? Do you have m100 and a cutting pad? What polisher are you using?