Jump to content

How to remove those fine scratches/marks caused by sandpapers?


number98

Recommended Posts

Hi, I saw a couple of guides on the Internet where it teaches how to remove scratches from a Rolex by sanding the scratches using various sandpaper and 3M paper and polish it after sanding it. I've tried with a lot of watches and every time after I polish it, it will reveal those fine scratches/marks which I believe left by those sandpapers. Did I left out a step before polishing? Do you guys know how to remove those fine marks/scratches as it's bothering me crazy. Thanks!

Link to comment
Share on other sites

2 minutes ago, nickelsilver said:

You have to remove all the scratches from the previous grade of abrasive with the next step. If you don't , they will show up later. It can be tedious, and difficult to know when you've really succeeded. What is the last grade you use before polishing?

I believe it's 3M Lapping Blue Paper. Sorry but I thought you use the sandpaper to remove the initial deep scratches only? Not remove the scratches caused by the abrasive?

Link to comment
Share on other sites

Scratches are scratches, you can do a lot with polishing but the goal with starting with a rougher abrasive like sandpaper (and then removing those scratches, and then those, and so forth) is to minimize distortion of the case shape. You can insist with the buffing wheel and get out some pretty serious marks but you round over edges and muck things up pretty fast.

The blue 3M is 9 micron as I recall, which is an excellent place to stop prior to buffing.

  • Like 1
Link to comment
Share on other sites

3 hours ago, measuretwice said:

OP, what sequence of grits are you using?  Start and something rough enough to get rid of the biggest scratch and work your way up to 2000 or finer, then polish

Hi, I am using 240, 400,600,1200,2000, 3M Yellow 12 Micron, Blue 9 Micron. Initially before I did all the sanding, it had scratches that were visible to the naked eyes. After doing the sanding and polishing using the Luxor Green Compound, I can see that although the surface has become shiny but it has a lot of fine scratches that weren't there before the sanding. 

So in that case what should I do? Should I restart the whole process again? Will it remove those fine scratches without adding any new scratches? Thanks! 

Edited by number98
Link to comment
Share on other sites

5 hours ago, nickelsilver said:

Scratches are scratches, you can do a lot with polishing but the goal with starting with a rougher abrasive like sandpaper (and then removing those scratches, and then those, and so forth) is to minimize distortion of the case shape. You can insist with the buffing wheel and get out some pretty serious marks but you round over edges and muck things up pretty fast.

The blue 3M is 9 micron as I recall, which is an excellent place to stop prior to buffing.

 

3 hours ago, measuretwice said:

OP, what sequence of grits are you using?  Start and something rough enough to get rid of the biggest scratch and work your way up to 2000 or finer, then polish

Attached is a photo of a bracelet where I polished two of its links. I haven't polished the rest of the links. Those blue circles are those fine scratches caused by the sandpaper.

 

InkedIMG_20191021_181911_LI.thumb.jpg.799b02ac97c1b29c7131a68a7a13ae58.jpg

Link to comment
Share on other sites

I'm assuming that the other 3 links in your photo have all been through the sanding process and are ready for polishing? In which case you need to spend a lot more time on each grade of paper; there is no way that that is the finish from a 9 micron lapping film, you still have the finish from the 600 or even 400 showing through.

In hand finishing there is absolutely no substitute for patience. You will need to go back to at least the 1200 or maybe an 800 and rework the surface until you have a uniform finish that is only as deep as the 800 can make it, there should be no evidence of any deeper scratches. Then move to the next finest grade and do the same, and so on. By the time you get to a 9 micron film the end result should look almost polished in its own right; there should be no evidence of the brushed finish in your photo, and no visible scratches.

You also need to be careful to clean the bracelet in between each grade of paper, preferably by flushing with water, to ensure that there are no particles of the coarser abrasive left behind that can wreak havoc with the end result.

Also make sure that the mop that you polish with is clean and uncontaminated. If in doubt use a new mop and never use the same mop for different grades.

Best of luck.

  • Like 1
Link to comment
Share on other sites

22 hours ago, number98 said:

 

Attached is a photo of a bracelet where I polished two of its links. I haven't polished the rest of the links. Those blue circles are those fine scratches caused by the sandpaper.

 

 

imo you're gone either too coarse to start with, or been too brief with a subsequent grit.  The grit refers to the size of the abrasive particles.  If a grit is say 400 in size, it will leave 400 sized scratches.  If the next grit up is 600, the idea is use 600 until the 400 sized scratches are gone.  If you leave 400 sized scratch, and keep going up, how are you going remove enough material to remove the scratch?

Despite a few BS claims out there of moving material around, abrasives remove material, full stop.  The only way to get rid of a scratch (with abrasives that is) is to remove enough material to bring all the surrounding material down to the level of the bottom of the scratch.  The reason for the progressive grits is to speed up the process.....but you never want to start too coarse or you creating deeper scratches than were there

Edited by measuretwice
  • Like 1
Link to comment
Share on other sites

23 hours ago, Marc said:

...

You also need to be careful to clean the bracelet in between each grade of paper, preferably by flushing with water, to ensure that there are no particles of the coarser abrasive left behind that can wreak havoc with the end result.

Also make sure that the mop that you polish with is clean and uncontaminated. If in doubt use a new mop and never use the same mop for different grades.

...

Failure to do adequate cleaning between polishing stages will contaminate lower sized grits with courser ones and this will tend to lead to the sort of results you are seeing. The object needs to be completely clean and free of any grit/compound. A quick wipe is not enough to get good results.


At each stage, you need to check carefully that you have a uniform satin or smokey finish. You need good lighting, and you need to inspect from multiple angles to observe this.

If polishing by hand, I tend to polish in a figure of eight pattern, changing the axis of the figure of eight by 90 degrees each time I change grit.

If machine polishing, then each grit should be polished at right angles to the previous courser one, to ensue that you bring down the previous troughs. If you always polish in the same direction, you will never completely remove the lines from the previous grit.

Many years ago I used to have to terminate fiber optic cables by hand from time to time, and the figure of eight polishing  technique was used to polish fiber ends. With a suitable jig and polishing compounds, and If done correctly the ends were typically optically smooth when inspected under a relatively powerful microscope, the process wasn't particularly elaborate or long winded, and from memory, only required three or four different grades of polishing compound. 

Edited by AndyHull
  • Like 2
Link to comment
Share on other sites

I don't see the point of spending time with paper when scratches are better removed with buffing, then polishing on a felt wheel. For an acceptable result you only need two rouge types, maybe three if aiming to perfection on a lustre finish. For brushed parts one proceeds to that immediately after orange Dialux and cleaning.

How to avoid rounding edges, just do not go over edges. That is easier when using a small narrow wheel, like 30mm, and concentrate the action on where the damage is, with the wheel crossing over the scratch. Do not go all around pointlessly. 

Edited by jdm
Link to comment
Share on other sites

  • 3 weeks later...
On 10/22/2019 at 2:39 AM, Marc said:

I'm assuming that the other 3 links in your photo have all been through the sanding process and are ready for polishing? In which case you need to spend a lot more time on each grade of paper; there is no way that that is the finish from a 9 micron lapping film, you still have the finish from the 600 or even 400 showing through.

In hand finishing there is absolutely no substitute for patience. You will need to go back to at least the 1200 or maybe an 800 and rework the surface until you have a uniform finish that is only as deep as the 800 can make it, there should be no evidence of any deeper scratches. Then move to the next finest grade and do the same, and so on. By the time you get to a 9 micron film the end result should look almost polished in its own right; there should be no evidence of the brushed finish in your photo, and no visible scratches.

You also need to be careful to clean the bracelet in between each grade of paper, preferably by flushing with water, to ensure that there are no particles of the coarser abrasive left behind that can wreak havoc with the end result.

Also make sure that the mop that you polish with is clean and uncontaminated. If in doubt use a new mop and never use the same mop for different grades.

Best of luck.

Hi thank you very much for the reply. So I tried again sanding it with 800 grit sandpaper but this time I sanded each surface for quite some time but when I use 1200 grit and subsequently those 3M film, I can still see those fine scratches despite spending a lot of time with the 800 and 1200. Do you think I should try crosshatching sanding instead of sanding it parallel? Thanks!

Link to comment
Share on other sites

At each stage, sand across the previous scratches, or sand in a random pattern.

Try a small amount of T-Cut or similar finishing polish on a cotton bud, and move in tiny circles or figures of eight. I'm sure you will make those scratches vanish.

You might find this interesting.

https://watchesbysjx.com/2015/01/explained-the-fine-art-of-black-polishing-aka-speculaire.html

It describes the art of black polishing, and as you will see from the article, the finishing polish stage uses a circular motion.

This ensures that you have as few parallel lines of defects as possible, and that the grinding marks are random and microscopic (typically of a scale of magnitude  around, or less than one wave lenght of light for extremely high polish).

This may seem daunting, but with a little practice, and patience you can hand polish to this level relatively consistently.

 

Link to comment
Share on other sites



×
×
  • Create New...