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A walking ball of wax
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3,549 Posts
Discussion Starter #1
I hear a lot of gibberish across boards that you cannot burn through paint with a PC.

Here is an example to show how easy it can be to burn through. You have to know your paint!

This is on Porsche 997s, using Meguiar's Scratch-X *by hand*!

IMG_8605.gif


Original Thread: http://www.autopia.org/forum/car-detailing/122309-made-huge-mistake-please-help.html

The OP was trying to repair a scratch. Well, the previous owner or bodyshop took off enough clear that he was able to burn though by hand! This has happened to me in a similar situation but with machine :read:.

The lesson, be cautious when working on a car you don't know the history of. If you have a machine that can read the depth of clear, great, use it. If you don't, stay on the safe side in these problem areas! Pay even more attention when working on plastic panels such as bumpers and mirrors!
 

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-Consistantly Retarded-
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624 Posts
thats gotta hurt, lol
 

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is probably detailing...
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6,749 Posts
Good point, but in most cases its safe to assume theres more than enough paint left there unless you've done some serious wet sanding or repair. That shit must've been fucking borderline transparent before he started to go thru it by hand.

This reminds me of how desperately I need to drop some coin on a good gauge.
 

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Detailer & PC Tech
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2,785 Posts
Good point, but in most cases its safe to assume theres more than enough paint left there unless you've done some serious wet sanding or repair. That shit must've been fucking borderline transparent before he started to go thru it by hand.

This reminds me of how desperately I need to drop some coin on a good gauge.
how much coin are you talking about?
 

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is Bi-Winning and a
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8,241 Posts
Damn! That is pretty crazy. I would have never thought about someone going through clear by hand much less by hand with Scratch X.
 

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Geresy Farms
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1,292 Posts
$850 and up for a GOOD one...and yes...I keep saying my next BIG detail will go towards the purchase of one but I always end up buying other crap instead :(
Yes and no. You don't need to spend $800. The highline II is a great buy. Though I know now days there are some cars out there that have a lot of fiberglass and plastic which you can't read. Well you can but the price for one is in the thousands.
 

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Banned
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6,955 Posts
Wait, so buffing a truck is actally taking some of the clear off? I never have really understood how buffing gets swirls out other than it uses heat and compound.
 

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Geresy Farms
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1,292 Posts
Yes you are removing clear coat. You are basically leveling the clear coat to a smooth surface. Removing swirls, RIDS, etc.
 

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Geresy Farms
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1,292 Posts
There's a lot of factors. But first why would you need to buff your truck a lot? There's a lot of talk about buffing, but really I think a lot more should be about washing/drying as that's where the problem is.

I wouldn't be hitting your truck with a compound/medium compound more then once a year if that. I will usually at the beginning of summer buff my trucks and girls car with a light polish to remove very fine swirls, etc. Then just one more time to jewel the paint.
 

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Banned
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6,955 Posts
Ok, I see what you mean. I wash mine and dry mine the right way, but I have always wondered how buffing actually works. But I see now.
 

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Geresy Farms
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1,292 Posts
Here's a nice article to explain it...

Another example thread, this time looking at removal rates and correction achieved from the full Menzerna range of polishes. The point - to see how the polishes perform, what paint removal corresponds to what correction, the abilities of the polishes and at the end, where it all goes wrong (purposefully in this case ;)).

So here we have our test panel - its the roof of my trusty banger, a Vauxhall Astra which is living out the last days of its life being polished before it goes to the scrappy! A test mule :) Out with the wire wool, lets get some scratches:

Dsc_0262.jpg


Now, we measure the thicknesses here using multiple readings and taking the average, and we calculate the absolute error in each reading also. The starting thickness here was measured to be:

Starting Thickness = 107.4 +/- 0.7um

For all of the ceramiclear abrasive polishes, the classic Zenith Point Technique was used: spread at 600rpm, work at 1500 - 1800rpm, refine at 1200, then 900rpm.

First up was 85RD Final Finish on a finishing pad, which delivered the following results:

Dsc_0263.jpg


Dsc_0264.jpg


Note how much worse the paint looks under the strip lighting - deeper marks are masked by the bright light sources such as the Sun Gun. Good level of correction though for a finishing polish on a finishing pad!

Paint thickness after 85RD:

After 85RD = 106.1 +/- 0.8um
*No removal rates calculated, only remaining thicknesses here. Subtraction gives removal rates, sum of the squares square rooted of the percentage error gives a measure of the error in this value for those interested :)

Next stage: 106FA on a polishing pad (W8006 from Meguiars), and we get:

Dsc_0265.jpg


Dsc_0266.jpg


Notably better correction, we are now just down to the deeper RDS. Paint left:

After 106FA = 102.9 +/- 0.8um
Looks to be more paint removed, as would be expected. This paint was prepolished to ensure soft upper layers removed.

Next stage: 203S Power Finish on a polishing pad:

Dsc_0267.jpg


Dsc_0268.jpg


A little better but not hugely, the remaining marks are deeper than it would seem, but then 203S did not seem to remove much paint:

After 203S = 101.8 +/- 0.8um

Certainly not compared to 106FA - into harder paint perhaps, or a slightly different abrasive style not being suited to this paint... Intensive Polish was next, so we'll see what that delivers:

Dsc_0269.jpg


Dsc_0270.jpg


A bit more in terms of correction, but at what cost in paint?:

After 85RD3.02 = 101.0 +/- 0.8um

Again, seems low, so looks like we are into harder paint now - this points more to there being a gradient in paint hardness on a finish, starting soft and getting harder the deeper you go which further supports the idea of there being UV degredation of upper clearcoat layers.

Now, we move to a different style of abrasive - a brittle, sharp abrasive compared to the ceramiclear's rounder abrasives. That of S34A Power Gloss, applied as above using Zenith method which although not typically Power Gloss, I wanted to keep the application the same here to avoid this being a variable.

The results:

Dsc_0271.jpg


Dsc_0272.jpg


Correction level superb, finish not bad either considering its a heavy cutting compound on a soft paint! Or is the paint soft? Debate :lol:

The paint left:

After S34A = 93.7 +/- 0.9um

A big amount of paint removed! Does this mean that the sharper abrasives better suit this paint for removal?

Now, at this stage, a second hit of Power Gloss would not be advised on a real detail... but as this is an experiment, lets do it, and see why its not advised!! :lol: Note the strike through after two hits:

Dsc_0273.jpg


Dsc_0274.jpg


Using the readings, you could see this coming - big chunk of paint removed first time, paint level now low, all factors pointing to another hit of PG being a no no! Paint left now:

After 2x S34A = 85.3 +/- 0.7um

Well into the strike though level...

So, what can we say after this little bit of fun?

First open ended question - different styles of abrasives... PG is more aggressive but it is hugely so here, is it that the sharper abrasives better suit this paint? Testing with the PO91L version of IP will tell us this answer here, so watch this space ;) But an interesting observation.

Note also, the removal rates slowing down again, pointing to paint getting harder the deeper we go for the same abrasive type. This is more consistent results with previous tests.

And, also interesting to see the Meznerna range's cutting and finishing abilities :)

Many thanks to Alex_E for his help with this test :)
 

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NVG-149 FTW!
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501 Posts
SSR1 doesn't even count. I use that shit A LOT.

But I have my truck repainted every 2 years.
No, It just so happens you hit deer every 2 years ;-).

You don't literally have your truck sprayed every 2 years, do you?
 

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is probably detailing...
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6,749 Posts
Yes and no. You don't need to spend $800. The highline II is a great buy. Though I know now days there are some cars out there that have a lot of fiberglass and plastic which you can't read. Well you can but the price for one is in the thousands.
Thats my problem... I do a fair amount of corvettes so I need it to read fiberglass ideally. Then theres also things like the SSS which has lower body cladding thats all plastic... as it becomes more and more commone I'd hate to spend $600-$800 on a gauge then turn around a few years later as cars continue to go plastic and buy another one.
 
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