Tips for Avoiding Scratches while wet-sanding

[yakky]

I've wet sanded a few cars so far, a couple to remove OP and a couple to mend clearcoat failure. I seem to get lots of scratches that are deeper than what the paper is rated for, I'm wondering what I can do to avoid these. They are a hassle when compounding afterwards as they take more than one pass with M84 to get rid of (after finishing with 3M 2000 grit).

[Mike Phillips]

Re: Tips for Avoiding Scratches while wet-sanding

These are called Tracers, the best way to avoid tracers when hand sanding is to first use the highest quality sanding paper you can find, some papers control the size and distribution of the abrasive particles better than others and using a paper with tight control over particle size and distribution will help you to reduce the potential for tracers.

Just as important is to work clean, that means starting with a clean shop and ending with a clean surface. It also means to use plenty of fresh water while sanding, using a spray bottle to add more water to the surface instead of using the water from your bucket which becomes contaminated.

Use equal pressure over your backing pad and use a grit guard in the bottom of your bucket to trap abrasive particles on the bottom of the bucket so you don't introduce them to the sanding process.

Use a little soap made for the wet sanding process to lubricate your paper and the finish, we offer #00 Hi Tech Wash, but you can use any Meguiar's car wash as they're all Body Shop Safe, and a lot of people in the refinishing industry use normal household dish soap.

These are off the tops of our heads, out of these the most important things you can do are to use the highest quality paper you can find, our Nikken Finishing papers use Unigrit Technology which offers,

• Uniform Particle Size
• Uniform Particle Distribution

Even by doing everything you can, tracers appear to be pretty much unavoidable 100% of the time. Machine sanding, either wet or dry enables you to avoid tracers all together if that's at all possible. Of course when you machine sand you can run into a related problem called Pigtails, which are like a tracers in that they are deeper scratches as compared to the scratches surrounding it but instead of the scratch being in a straight line, it's in little circles that look like a curled pig's tail.

It's caused by having a larger abrasive particle get between your sanding paper and the finish, the the oscillating action of a DA sander forces the particle into the paint instilling the pigtail scratch. These will require either more sanding to remove or more compounding.

Wet sanding, also called color sanding is the hardest finish related process there is to do, not only is the work hard, but it must be performed by someone that is totally focused on the task at hand, you only have a few mils of paint to work with and if you remove too much of the working film-build, you could either sand through the clear coat or you could buff through the clear coat when you go to remove your sanding marks.

Removing sanding marks requires the use of a rotary buffer and in most cases you'll have to rotary buff the entire car twice, that's a lot of work by itself.

[yakky]

Re: Tips for Avoiding Scratches while wet-sanding

Mike,

Thanks for the explanation. While I have loosely stuck to the mentioned principals, I need to strive to keep the paper and surface clean. I also need to try the Meguiars papers and see if I get an improvement. Saying that they are unavoidable is somewhat disheartening though, as the tracers end up killing so much of the film build because of having to use so much compound.

Dan

[Mike Phillips]

Re: Tips for Avoiding Scratches while wet-sanding

Mike,

Thanks for the explanation. While I have loosely stuck to the mentioned principals, I need to strive to keep the paper and surface clean. I also need to try the Meguiar's papers and see if I get an improvement. Saying that they are unavoidable is somewhat disheartening though, as the tracers end up killing so much of the film build because of having to use so much compound.

Dan

You nailed it. I'm sure it's doable, I'm sure there are craftsmen that are able to sand without tracers, I know it's also a matter of how hard you look for them after sanding, you care, others don't, so they don't see them.

We see them when we sand and we usually use a piece of sand paper about the size of a postage stamp to feather them out instead of re-sanding, or compounding.

You might try this sometime, that is Feathersanding. Check out this thread,

Feathersanding

[yakky]

Re: Tips for Avoiding Scratches while wet-sanding

Thanks for the helpful info Mike!

[Mike Phillips]

Re: Tips for Avoiding Scratches while wet-sanding

Thanks for the helpful info Mike!

It's always a Team Effort here at Meguiar's!

[repo]

Re: Tips for Avoiding Scratches while wet-sanding

Mike, what are you using to equal out the pressure on the sand paper while sanding or are you just using a finger? Wet or Dry? Or even better.... could you post a tutorial?

[cuprajake]

Re: Tips for Avoiding Scratches while wet-sanding

hi,

first post here and all,

now i dont know if im allowed to mention other products but here's what i find works well in relieving the little swirls


in the uk 3m produce a tri-zact pad i presume you guys can get them, once i have d-a'd the car with 1500's discs i then wet flat with the trizact(3000 grit) this had an abrasive film to them so they cut only a tiny ammount but enough to get rid of the pig tails as you call them, as it cuts it also brings the surface up alittle making buffing a whole lot easier


cheers jake

[Mike Phillips]

Re: Tips for Avoiding Scratches while wet-sanding

hi,

first post here and all,

now i dont know if im allowed to mention other products but here's what i find works well in relieving the little swirls


in the uk 3m produce a tri-zact pad i presume you guys can get them, once i have d-a'd the car with 1500's discs i then wet flat with the trizact(3000 grit) this had an abrasive film to them so they cut only a tiny ammount but enough to get rid of the pig tails as you call them, as it cuts it also brings the surface up alittle making buffing a whole lot easier


cheers jake

This would be a great tip for the 3M forum.


We offer a paper comparable to the Tri-Zact system call Nikken that we used in the examples sited in this thread regardless of whose paper you use, you will ALWAYS have to use good technique, like equal pressure.

[Mike Phillips]

Re: Tips for Avoiding Scratches while wet-sanding

Mike, what are you using to equal out the pressure on the sand paper while sanding or are you just using a finger? Wet or Dry? Or even better.... could you post a tutorial?

When wet-sanding with just your finger, you do the best you can, you carefully apply pressure over the face of the paper with your finger, that kind of sums up the technique except to note that it's all about focusing on the task at hand and that when you do this kind of thing you are paying close attention and working very carefully, with emphasis on the words very and carefully.

[cuprajake]

Re: Tips for Avoiding Scratches while wet-sanding

yup sorry for that, but its not a flatting paper as such i will dig some pics out

as i recently did my impreza

first i dry flat with 1500 discs


then you trizact wet



here are pics of what i use the trizact are soft foamy type things



jake

[cuprajake]

Re: Tips for Avoiding Scratches while wet-sanding

here are pics









so far the car has only has compond and final glaze no polish or wax as the paint hasn't fully cured.

i will be giving it some nice coats of my gold class wax, and when its gone i may try the nxt gen wax, i used the last of my soft wash soap today so ordered some nxt gen shampoo


jake

[Mike Phillips]

Re: Tips for Avoiding Scratches while wet-sanding

yup sorry for that, but its not a flatting paper as such i will dig some pics out

We stand corrected.

Currently we don't offer a round sanding paper for use with a D.A. Sander. At this time we only offer rectangular sheets of finishing paper for hand sanding.

3M and others do offer the round papers for use with D.A. sanders.

Nice work by the way!

[cuprajake]

Re: Tips for Avoiding Scratches while wet-sanding

its not so much the sanding side, d-a is lazy hahahahah

they are something to look into if you can't get one id gladly send you one over to see how they work, i use them by hand too in awkward spots

thanks for the compliments


jake