How do I finish off stone chip repair and bumper scuff ??

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Silverrocket

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Hello all.
Question: should I 3000 grit sand OR use a compound then polish OR just a medium strength polish?
I'm a "weekend warrior" learning on the job. I have a rotary polisher (Silverline 264569) lots of sandpapers and an abrasive pen.


Background
I'm on the last stage of a stone chip and bumper scuff repair on a BMW 3 series 2008 in Titan Silver Metallic.
I've done a huge amount of reading on it all, but TBH I still feel a bit lost... and cautious - given that it didn't really go exactly as in the Youtube videos.
BMW paint is very thick and "blobby", and I only really got success in sanding it with an abrasive pen. (Using sandpaper on a pencil top eraser seemed to get me nowhere)

I've filled in 8 stone chips, some of which were pretty large. I've also sanded a scuff from a black car that impacted the bumper, and put some touchup paint on.
All were BMW's own paints and clearcoat. In the pics are the bumper scuff, 3 pics of "double chips" and 2 pics of single chips. All the pics show touched up paint work ie the work done to today.

The current pictures show the paint after clearcoat and touchup paint (to fill the chips/repair the scuff), but before final sanding or compounding or polishing.
It feels "fairly" smooth, but definitely noticeable with finger touch.

The question
How would people recommend I finish it all of?

View attachment 73220View attachment 73221View attachment 73222View attachment 73223View attachment 73224View attachment 73225

Should I:-

1)Use 1500 or 2000, then 3000, then 4000 grit. And finally a polish with the Rotary polisher and a week later a wax?
Would Menzerna Intensive Polish then a finishing polish be good choices here?I notice an older thread uses that tactic.

OR should I:-2)Use a stronger compound, such as Meguiars M105 then polish and wax after that?
How much sanding might I need to do before that? I would guess much less sanding?
Or Meguiars D300 or Meguiars Ultimate?


Is a sanding pen the equivalent of far higher a grit, or is it still comparable to a 1500 grit?

OR

3)Adopt another approach again? (Please advise).

Final notes
I'm cautious about using too powerful a compound. The car is a little grubby in the pics, but its only really the chips and bumper scuff that I want to correct. Generally the paint is in otherwise excellent condition for its age.
I'm also not entirely clear on which machine pad to use with any compound or polishes.

Of course I will post pics of any completed work, when its done.
Many thanks for any ideas thoughts you may have.

PS
the video I based my repair strategy around was this one.
How To Correctly "Paint Touch-Up" Stone Chips On Your Car To Get The Best Results! - YouTube.
A medium compound was recommended, but I've since found that the whole compound selection stage seems to be a potential minefield! Also, I found I needed an abrasive pen rather than sandpaper in the early stages.
 
This is a tough process to learn or provide instruction other than in-person.

That said, if you want the repairs "leveled", that is best accomplished by sanding. As for the grit, I'd start with 1500. You can, but do not have to, follow that up with something finer. From my perspective, anything finer than 3000 is a waste of time.

Once sanded I would compound/polish by hand. Although you can certainly use a polisher, small touch-up's can be easily polished by hand.

And one final note... Since you are working with a metallic silver color, keep your expectations in-check as far as color matching goes.
 
Brilliant thanks.

1) Would it be ok to sand down using the abrasive pen on the "gentle setting" ie having the fibres long in the pen? Would 3000 grit get out the marks it leaves?

I'd decided to redo the paint touchups first time around, and sanding down with 1500 on an eraser tipped pencil seemed hopeless. So I used the sanding pen with far more success.
Do I literally just want it smooth-ish?
I was wondering how far a compound might fill in, given that they are actually small chips that just happen to stand out like a sore thumb in certain light as they are duller silver than the rest of the paint.

2)Any ideas which compound and polish should I use?
Megiuars seem to have loads. Ultimate, D300, M105.
Would a professional compound be "safe" for me, given that its tiny areas?
I was tempted to try the retail product Megiuars Ultimate but heard its not great for a rotary polisher.
And M105 seems to be very strong... maybe too strong for a "weekend warrior", and prone to "dusting".

Alternatively I'm wondering if a strong polish will be all thats necessary after 3000 grit or gently using the sanding pen.
Many thanks.

PS just seen your 2nd post. Thanks, will take a look.
 
Silverrocket said:
1) Would it be ok to sand down using the abrasive pen on the "gentle setting" ie having the fibres long in the pen? Would 3000 grit get out the marks it leaves?
Click to expand...

I can't comment on the abrasive pen as I have never used one (or even seen one).

Silverrocket said:
Do I literally just want it smooth-ish?
I was wondering how far a compound might fill in, given that they are actually small chips that just happen to stand out like a sore thumb in certain light as they are duller silver than the rest of the paint.
Click to expand...

The smoother the better... But you need to balance any sanding with the associated risks. Don't get too carried away with the sanding.

I'm not sure what you mean by the compound "filling in".

You should be able to polish out the "dullness", but don't expect a perfect color match. It just can't be done with a brush and a metallic color.

Silverrocket said:
2)Any ideas which compound and polish should I use?
Megiuars seem to have loads. Ultimate, D300, M105.
Would a professional compound be "safe" for me, given that its tiny areas?
I was tempted to try the retail product Megiuars Ultimate but heard its not great for a rotary polisher.
And M105 seems to be very strong... maybe too strong for a "weekend warrior", and prone to "dusting".

Alternatively I'm wondering if a strong polish will be all thats necessary after 3000 grit or gently using the sanding pen.
Many thanks.
Click to expand...

I think any of these compounds/polishes will work. You certainly can't go wrong with the Ultimate line.
 
Silverrocket said:
Hello all

Question: should I 3000 grit sand OR use a compound then polish OR just a medium strength polish?

I'm a "weekend warrior" learning on the job. I have a rotary polisher (Silverline 264569) lots of sandpapers and an abrasive pen.


Background[/B
I'm on the last stage of a stone chip and bumper scuff repair on a BMW 3 series 2008 in Titan Silver Metallic.
Click to expand...




It's never any fun playing the part of Debbie Downer, (sorry to all the Debbies in the world), but in an effort to merely provide you with some caution-information.


The factory clearcoat on modern cars is thin. Really thin. Thinner than a Post-it Note. See my article here,

Clearcoats are thin by Mike Phillips



Then there's this and the point of the below articles is when sanding and then buffing on factory clearcoat - it's just a matter of time before you turn your buffing pad over and see the color of the basecoat on your pad. :bolt:

Wetsanding removes paint - Compounding removes paint - Polishing removes a little paint



And this,

What it looks like when you buff through the clearcoat - Burn Through - Strike Through - Mike Phillips



And I like the tip I share here,

Considerations for removing paint defects - the BIG PICTURE


Here's a free tip...

If you're reading this and you're thinking about tackling some type of paint defect on your car. BEFORE you start the project, just for fun - take the car to a few local body shops and simply ask them,

What will it cost me to repaint the hood? (or the blank)


Now let that sink in. Besides the cost and hassle of getting a panel repainted - you'll now have a car that no longer has all the factory paint.



:)
 
Besides all the Negative Nancy stuff I shared above, (apologies to all the Nancys in the world),


Here's my suggestion...

After you're done applying any touch-up paint.

Let the paint dry for 2-3 weeks. If you can, park your car outside in hot sunny weather. You want the touch-up paint to full dry and harden.

Then LIGHTLY sand, or even just SCUFF the tops a little.

Then carefully, carefully buff out your sanding marks. Above all else - DO NOT GET THE AREA HOT. If you get the section of paint hot where you're buffing what usually happens is the touch-up paint softens and your buffing pad will yank it off the car.

Now you get to start over. Only now, due to the work you've done in this area, it's likely the paint is thinner than when you started. Thus you increase the risk of buffing through the surrounding clear when working on the touch-up paint.


I've done this type of work successfully. I've also experienced what I've described above.


For me, dab on some touch-up paint, less is more and then walk away.


:)
 
I'm with Mike, touch it up and walk away. The cure may very well be worse than the disease.
 
Prep Pen - Adjustable Sanding Pen

This was the type of pen I used. Its glass fibres. You can set it to long, where the fibres bend and act softly. Or short, and you can really push down harder to get the equivalent of a lower grit. It doesn't seem to leave noticeable "channels" in the way a low grit sandpaper would, but I suppose its guesswork as to what grit equivalent its like. The promo material says it won't scratch chrome. The broken shards can be potentially dangerous tho.

Having seen some of the compound videos/more abrasive polishouts of scratches, I was thinking that I could get past the look you get with touchup and no polish.
Right now, even tho the paint is the same, the patch ups can really stick out in some lights.
 
Mike Phillips said:
Besides all the Negative Nancy stuff I shared above, (apologies to all the Nancys in the world),


Here's my suggestion...

After you're done applying any touch-up paint.

Let the paint dry for 2-3 weeks. If you can, park your car outside in hot sunny weather. You want the touch-up paint to full dry and harden.

Then LIGHTLY sand, or even just SCUFF the tops a little.

Then carefully, carefully buff out your sanding marks. Above all else - DO NOT GET THE AREA HOT. If you get the section of paint hot where you're buffing what usually happens is the touch-up paint softens and your buffing pad will yank it off the car.

Now you get to start over. Only now, due to the work you've done in this area, it's likely the paint is thinner than when you started. Thus you increase the risk of buffing through the surrounding clear when working on the touch-up paint.


I've done this type of work successfully. I've also experienced what I've described above.


For me, dab on some touch-up paint, less is more and then walk away.


:)
Click to expand...

Hi Mike.
Thanks for all your detailed info.
I'm keen to give some sort of polishing or compounding or machine work a go.
I know I don't want to use too much compound, maybe not too strong a compound. And not leave the machine on too long or have it too hard or fast.
But I'm keen to at least try and develop my skills in a cautious way. Because at least once I've learned it, I have a skill I can keep.

Chip repair companies in England (the mobile ones) just refuse to look at metallic.
I had a rough quote for a bonnet respray and it was a ridiculous amount which wasn't justified given the vehicle, IMO. One or two chip repair companies reckoned I should try and fix it myself given the multi day nature of it all. (They try and do the whole job in 2 hrs or so).

I think I will try and cautiously flatten the paint. Have you used sanding pens? Would you recommend one instead of the 1500 grit, before final refinement with 3000 or higher grit?
My final debate is whether to use a polish or compound and which one. Together with machine and what pad. Or whether to try hand, then maybe a final polish using my machine. Figuring out which compound/polish and equipment seem really hard tho.

Maybe I could try and gentle polish, then move onto a compound if that failed?
 
Mike Phillips said:
Besides all the Negative Nancy stuff I shared above, (apologies to all the Nancys in the world),


Here's my suggestion...

After you're done applying any touch-up paint.

Let the paint dry for 2-3 weeks. If you can, park your car outside in hot sunny weather. You want the touch-up paint to full dry and harden.

Then LIGHTLY sand, or even just SCUFF the tops a little.

Then carefully, carefully buff out your sanding marks. Above all else - DO NOT GET THE AREA HOT. If you get the section of paint hot where you're buffing what usually happens is the touch-up paint softens and your buffing pad will yank it off the car.

Now you get to start over. Only now, due to the work you've done in this area, it's likely the paint is thinner than when you started. Thus you increase the risk of buffing through the surrounding clear when working on the touch-up paint.


I've done this type of work successfully. I've also experienced what I've described above.


For me, dab on some touch-up paint, less is more and then walk away.


:)
Click to expand...

PS Sorry this is probably a silly question here. You would recommend I flatten the touchup to be fairly smooth with the surrounding area first?
ie with 1500 grit, or a sanding pen?


My chip repairs are currently "mostly flat", but one or two are a little raised right now, compared to the surrounding area.
 
Silverrocket said:
PS Sorry this is probably a silly question here. You would recommend I flatten the touchup to be fairly smooth with the surrounding area first?
ie with 1500 grit, or a sanding pen?


My chip repairs are currently "mostly flat", but one or two are a little raised right now, compared to the surrounding area.
Click to expand...

Have you looked into Dr. ColorChip? Great diy for paint chips


Sent from my iPhone using Tapatalk
 
I hear its easier to use than BMW's own paint.
But I also hear the good results aren't as good as BMW paint.
Right now, I've sort of filled in the chips with BMW paint. (Perhaps there's some more bits to fill).
So basically I'm at finishing off stage.
I've also bumped into a prof detailer who may be a reasonably priced solution if I "run aground" in my efforts.
 
After reading your recent posts and questions...

Let me reiterate... Don't expect perfection! Keep your expectations "real". Being a metallic color complicates the issue as the color and metallic dispersion within the chip is never going to match anywhere close to perfectly.

For compounding/polishing, put away your polisher (unless you have a 1-incher). And even then, I would still opt for hand polishing the initial touch-up. It is so much easier to control the amount of paint removed by hand. Once you have hand polished all of the chip repairs, then going over the entire panel with your polisher is a good final step.

I think you are over-thinking the compound vs. polish product selection. Either will work for the initial cut although the effort required will vary between products. Regardless of the product used, you're going to be experimenting to some point. The hardness of the touch-up paint is not going to be the same as the original finish so some experimenting is required to achieve the desired results.
 
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