Wet Sanding a scratch

[desgnr]

Will wet sanding a scratch remove my clear coat ?
What is the safest grit to use ?
What should i polish with after wet sanding ?

[Murr1525]

Re: Wet Sanding a scratch

Can we see the scratch?

[greg0303]

Re: Wet Sanding a scratch

Correcting any below surface defect (water spot, oxidation, swirl marks, scratches, etc.) requires removal of small amount of paint. Type of defect and hardness of your car's paint will determine how to safely and effectively deal with them.

Paint scratches can be removed with products which abrade paint (paint cleaners/ compounds, cleaner/ polishes, cleaner/ waxes). If it's an isolated problem then ScratchX 2.0 used by hand with soft foam applicator would be a good starting point. For more stubborn scratches Ultimate Compound with car polisher may be needed.

Wet sanding is the most aggressive approach. If all other methods are not effective/ fast enough sanding paint with 2000 - 3000 grit sand paper may be an option but it would require sanding mark removal and gloss restoring polishing after. Before you proceed with sanding it's wise to check how much paint is left in that area and paint thickness gauge (PTG) is needed for that (unless it's your own vehicle and you know nothing aggressive was done to it before).

Is it your own vehicle or your client's ? Is a single stage paint or base coat/ clear coat ? I assume it's BC/CC as you said wet sanding not color sanding.

Pics would be really helpful to give you deeper advice.

[Michael Stoops]

Re: Wet Sanding a scratch

Removing any below surface defect requires the removal of at least some surrounding paint. If that defect is a series of very fine swirl marks (technically still scratches in the paint) then the amount of paint removed in order to eliminate the defect is minimal; inconsequential really. The deeper the defect, the more paint you need to remove to level down to the bottom of that defect. Which is why a key scratch that goes down to primer can't just be buffed out - you'd have to level the surrounding area down to the primer to reach the bottom of the scratch, which obviously would give less than desirable results.

Between a fine swirl and a key scratch down to the primer (or bare metal!!) is a wide range of depth possibilities. What's critical to keep in mind is that your clear coat is only about 1.5 to 2 mils thick (that's 2/1000 of an inch or less) and practically every manufacturer will tell you that if you remove more than 0.5 mils you must refinish the vehicle. So you don't really have a lot of wiggle room here. The generally accepted rule of thumb is that if you can feel the scratch with your fingernail you probably can't fully remove it, at least not safely. If you can barely feel it then you can probably buff it out; if it's pretty noticeable then some light feather sanding with 1500 or 2000 grit wet sanding can usually be a safe approach for correction; but if you're fingernail really drops into the scratch then complete removal is probably not safe and the best you can do is minimize the appearance of the scratch. Of course, determining this by feel takes practice and experience.

If you do go the sanding route you'd better be prepared to remove the sanding marks once you've put them in. Even at 2000 grit these are usually much, much more difficult to remove than typical swirl marks and a DA buffer usually won't get the job done; a rotary is the tool of choice here, and there's a bit of a learning curve to that tool as well.

Knowing a bit more about this scratch will help though.

[mis3]

Re: Wet Sanding a scratch

I read in this forum that if you can feel the scratch by your finger nail, it is too deep for home repair.

[Shawn T.]

Re: Wet Sanding a scratch

If you choose to wet-sand, here is an example of some scratches that needed to be wetsanded.....First attempt at wetsanding

[Michael Stoops]

Re: Wet Sanding a scratch

Shawn, just an FYI - we edited your post to make the link more obvious. We didn't want anyone missing out!

[Shawn T.]

Re: Wet Sanding a scratch

Shawn, just an FYI - we edited your post to make the link more obvious. We didn't want anyone missing out!

Thanks Mike!