The CD scratch test

[Vikas]

I decided to do my own experiment. I chose a blank CD-R which had some deep visible scratches but the rest of the finish was pristine. My aim was to remove those scratches and still maintain the finish.

At first I tried Meguiars SwirlX and Ultimate Compound by hand. There was zero difference. Next came 1500 and 2000 wet sand. The scratches were minimized but the finish became extremely poor. Used UC and SwirlX but it did not even make a dent.

Then I used 2500 and 3000 wet paper. That did cut down on the scratches but the finish was still extremely cloudy. I do not have any higher grit papers to try.

I then went back to UC and SwirlX again with hand but the cloudiness remained.

I also tried the Meguiars plastic polish #10 and #17 and it too made little difference.

Finally spun the polishing pad on the rotary and used SwirlX and held the scratched portion of the CD on it. Afterwards, did the same thing with BF polish. There was remarkable difference but could not get the mirror finish back.

I know from experience and the same steps taken on my Honda or Toyota paints do achieve great results but neither of the 14 year old vehicles have the original mirror finish to compare against.

How relevant is the CD test? What regiment can get the CD finish back to its pristine state?

 

[Brybo86]

qwertydude will know, he is the CD test master...

 

[dparm]

I don't understand why you think products designed for automotive paint will be effective on the special plastics used on a CD.

 

[Rolla07]

One major issue with your test!! You didnt try using Nu Finish on it!!! You have to use Nu Finish to prove that it will result in more scratches, rather than improving it LOL.

 

[NHGUY]

Did the CD still work afterwards?

 

[kkreit01]

I've used PlastX by hand, and it helped.

 

[Vikas]

Well, the CD-R was blank to begin with and I suspect it remained blank afterwards

 

[qwertydude]

I decided to post again. The CD test is actually comparable to some of the ultra hard German paints I've encountered over the years. Hard not only in terms of material hardness but in terms of getting actual correction out of without inducing haze or cloudiness. In particular Mercedes Benz non-metallic black is insanely difficult to get a decent correction out of.

With that said I didn't find the CD too difficult. I didn't even break out my DA or higher end ultra finishing polishes like Menzerna SF4000. This was done with just my wax spreader and wool bonnet. So if you can't achieve a finish at least this good with better stuff, you need to work on technique.

Here's a control shot. The left side was sanded with 800 grit sandpaper. The right side is the finished product. It was trashed essentially. So if the scratch was deep, sand it with 800 grit til the scratch leveled off and you can have comparable results to this. I'll detail the process later in this post.

Here's a bright closeup to reveal the extent of the initial damage.

Here's a bright closeup to reveal the finished product. There's hardly any hint of cloudiness and what's visible is only visible under a very bright point source led light. In normal lighting it looks just like a normal DVD.

The technique that brought me here was multi step wet sanding since if the damage is severe wet sanding is your only option. The initial sanding was 800 grit dry sanding over the whole DVD to approximate heavy damage. I started with 1000 grit wet sanding and then followed with 2000 grit wet sanding. It's very important to ensure the 2000 grit completely eliminates the 1000 grit wet sanding marks or you'll never get a truly mirror finish. You'll get the cloudiness. The trick with wet sanding is to move the sandpaper in straight lines and making a cross hatching pattern moving the sandpaper in circles I find tends to dislodge particles of abrasive and makes RIDS that are visible after polishing under inspection lights.

Then surprisingly all I did was use Ultimate Compound by hand with a microfiber cloth. You have to press a little more hard since this is by hand and rub the compound in small circles on the DVD like normal. Do this until the sanding haze clears up. Took about a minute. I didn't bother to take a picture but the finish pretty much ends up like the same when I compared NuFinish and Ultimate Compound.

And then I simply took out my trusty wax spreader and wool bonnet and applied 4 lines of Ultimate Polish to the bonnet and just held it down to polish for about a minute. Then of course my little trade secret of jewelling. Lighten up the pressure on the polisher and let the polisher spin up to maximum RPM and jewel for another minute.

Had I used my DA, finishing pad and Menzerna SF4000 it would be indistinguiashable from OEM factory new DVD but certainly hard to tell in photos and then of course I'd be accused of simply cheating and photographing a new DVD, then they'd want videos and signed witnesses with notarized documentation. But I wanted to show with just a little practice again just what's possible with OTC polish and a cheapy wax spreader.

So if you're having trouble with the CD test it also might mean your detailing technique could use a little "polishing". For one thing if I can get these kinds of results on a CD which is a difficult surface to really work with but only about as much as hard German clears, imagine just how picky I am with the surface finish of the cars I own and detailed. So when I say my details leave a paint flawless. You can bet your bottom dollar it's flawless.

 

[Vikas]

Do this with half and half; start with a brand new CD/DVD and scratch the half and then see if you can get it back to the mirror finish. As far as I can see from your pictures, I still see the haziness/cloudiness under the bright light. I agree with you that with normal lighting it would look like a new CD but not under A/B comparison. I too was able to get "good enough" results but it was pretty apparent which half was unmolested. I mean I was able to achieve the similar results as what you have shown here but I wanted better mirror finish than that.

 

[qwertydude]

This did start with a brand new DVD and the whole DVD was sanded with 800 grit so I was able with all the scratches there to remove all subsequent sanding marks. I didn't sand just half the CD with 800 grit the whole CD was scratched with 800 grit. So that's about as restored as you can get. For one thing not even your paint would be in this good a condition. Paint unless perfectly wet sanded flat would tend not to be as mirror finish as this which is why it may look cloudy under an inspection light but I've yet to see even a single stage professional polish approach a surface flatness like a CD can achieve save for a few cars that were very specifically custom painted show cars with hundreds of hours of wet sanding and polishing. If your paint was as perfectly flat as this it would look better than a show car but would quickly degrade to a normal polish since acrylic is softer than polycarbonate. Believe me I wet sanded my BMW after painting it and gave it the full treatment and even after you could see that slight "hazing" under an inspection light but even in full sunlight the finish was immaculate.

If you've ever polished a single stage black car the above surface finish is about as good as you're gonna get. Try getting a can of spray paint and paint a metal panel with it. Then let it dry when it dries by itself the actual gloss will be about as good as you can get. Once you try to polish it and inspect it you'll see the gloss drop a bit even though flatness reflectivity will be better. The only way you can really achieve the original OEM CD finish and reflectivity is by remelting and resolidifying the plastic since that's how it comes from the factory.

That particular lighting technique exposes a lot more surface imperfection than you'll ever see in real life. And that's including a full sun shot and night time parking lot shots. Basically if you need to see the imperfections close up under specialized lighting technique it's pretty much a moot point.

Considering most people think Ultimate compound leaves a good enough finish but if you compare the difference between Ultimate Compound and Ultimate Polish even between the two CD tests you'd be able to reason that a proper polish with Ultimate compound is about as good as you can possibly expect short of a professionally done show car.

If you want to see what the original DVD looks like here's a picture of an OEM new finish as part of the NUFinish UC comparison I did.

 

[friendly_jacek]

Dudes,
we really need to know if those CD/DVDs work after.

 

[Vikas]

Work? What does work have to do with how it looks? We are all vain here! It is all show and no go.

 

[friendly_jacek]

Relax!

 

[SatinSilver]

Originally Posted By: friendly_jacek
Dudes,
we really need to know if those CD/DVDs work after.


This is no joking matter friendly_jacek.








Nah, I'm just joking.

 

[qwertydude]

They do work just fine. I redid the test this time writing on a new DVD-RW a full 4 gb movie onto one so the whole disc was used. Then I scratched about 1/4 of it with the 800 grit sandpaper. The DVD wouldn't work. It would actually lock up my DVD drive for a couple minutes while you hear it struggle to play.

Then the same procedure was used to restore it. It played just fine. Afterwards it erased and rewrote and played just fine. So this method does work if DVD restoration is what you need it for. It should work anyways since the error correction built into DVD players works for quite severe scratching.

The thing though is most CD's and DVD's the most delicate side isn't the bottom where it's played. It's the top which isn't polycarbonate. It's a simple lacquer clear which is very thin and scrapes off much easier, taking the reflective metal off with it than the DVD on the bottom can scratch.