[driverman]

I've been researching clear coat thickness and the effects of paint correction. Here's what I've found:

- New cars come with 100-180 microns of paint, including primer, color and clear coats.
- The clear coat is 35-50 microns.
- Most auto manufacturers recommend that a maximum of 8 microns of clear coat be removed to leave enough clear coat to protect the color coat against UV damage. One article suggests 12 microns can be removed.
- Light compounding removes 1-2 microns.
- Heavy compounding removes about 3 microns.

Given all of that, a new car can handle 3-4 heavy compoundings over its life. If we work on our own car that we bought new, we'll know the history of the car (unless it was damaged and repaired before we took delivery). But if we work on someone else's car or a car we bought used, we won't know the history of the car. Therefore, doing a moderate or major paint correction without a paint thickness gauge (PTG) seems risky.

What do the pros think? They've learned from experience. Are these numbers about right? Is it risky to do medium to heavy compounding on a car without a PTG? If more clear coat is removed than the guidelines above, we'd never know it for sure without an expensive PTG that shows the depth of all three paint layers, right? We might suspect that's happened if the overall readings are low (<100 microns), right? If that happens, will vigilant waxing/sealing protect the remaining the clear coat and color coat?

Many thanks.

[Bobble]

Not a pro but a hobbyist and if using a DA you wont have to worry as much if at all as it's tough to really remove much clear especially if you use proper technique.
A rotary is another story and that requires good techinique and skill which IMO should be left to the pros. They can burn thru in a heartbeat when in the wrong hands.

[MuttGrunt]

Very good questions being asked Driverman. Would you mind if I turned this into a professional article?

[x3man1994]

Originally Posted by MuttGrunt

Very good questions being asked Driverman. Would you mind if I turned this into a professional article?

^^^^^

do it I love the ask a pro blog make it with pictures and all, I love reading stuff like this!

[driverman]

Originally Posted by MuttGrunt

Very good questions being asked Driverman. Would you mind if I turned this into a professional article?

Not all all. Thanks for asking. The purpose of these forums is to share information with fellow-enthusiasts. Is it fair to ask that you share your article with us?

[Envious Eric]

marc will no doubt do a great write up with this one! he has all the cool PTG's now! LUCKY!!!!

[MuttGrunt]

Originally Posted by driverman

Not all all. Thanks for asking. The purpose of these forums is to share information with fellow-enthusiasts. Is it fair to ask that you share your article with us?

Of course it'll be public. I won't be able to link it directly as it'll be spam due to me not being a paying sponsor. I'll make sure to send you a link through PM if you'd like.

[SteveH]

Originally Posted by MuttGrunt

Of course it'll be public. I won't be able to link it directly as it'll be spam due to me not being a paying sponsor. I'll make sure to send you a link through PM if you'd like.

Me toooo

[driverman]

Originally Posted by MuttGrunt

Of course it'll be public. I won't be able to link it directly as it'll be spam due to me not being a paying sponsor. I'll make sure to send you a link through PM if you'd like.

Thanks MuttGrunt. Greatly appreciated.

[driverman]

Originally Posted by Bobble

Not a pro but a hobbyist and if using a DA you wont have to worry as much if at all as it's tough to really remove much clear especially if you use proper technique.

It appears you're right with a medium cut polish.

I started working on my daughter's 98 Civic yesterday. I used a Flex 3401, Menzerna SIP and an orange LC pad. I took PTG readings before, during and after multiple passes. The results were dramatic, but very little clear coat was removed (well within the margin of error of the PTG).

I wonder what would happen with a more aggressive pad and Power Gloss or Meguiars 105. I think I'll buy some Power Gloss and a yellow pad and try it out on the worst panel on the car.

[Bobble]

And the by product to that is the Flex is by far the most powerful DA polisher there is so it's theoretically even less with a PCXP or the Megs and GG machines. Rotary buffers require skill and techinique which only comes with practice and experience. I've only used one once and it was not pretty. If I need rotary work done I turn to the pros quickly. I think everyone should know where there paint is at sometime in it's life.

I doubt there will be much more taken off as the DA's are pretty safe with decent technique and paying attention to what you do. I'd love to see the difference between same polishes and different pads, say the LC Orange versus a Surbuf as you can really get some decent correction out of surbuf pads. Options and info is good.

Marc will the article be on DI Ask the Pro blogs? There is so much great info there from all you guys everybody should read that stuff.

[bimmertt]

Looking forward to the article.

[MuttGrunt]

Just as a head's up, the article will certainly be made for the DetailedImage.com Ask-A-Pro blog, but won't likely be ready to go for another week. I currently have an article up that's been doing well, and a new article is around the corner (5 Products for advanced users) and I hope to have it posted this weekend. I've started on the draft for the article on "Paint correction's effect on thickness" but I have a lot of writing/explaining to do, let alone I need to get a few pics uploaded for it.

In the mean time for anyone that can't wait, just know that you're clear-coat is thick enough to polish many times over depending on how you care for her. If you only do very aggressive correction stages and you leave the car in the sun / outside non-stop, you'll be on the low end of how many times the car can be polished. If you do a heavy initial correction and then care for her properly so that only light work needs to be done in the future, you can have many many (12-18+) polishing sessions easily.

I'm hopeful an even more experienced detailer (someone that's been doing this since I was in grade school) like Bob Willis of Auto Concierge can stop in and add his two cents as I'm willing to bet a guy like Bob likely has cars on his client list that he's worked on more than 6 times and the car is still plenty healthy.

[tofu-]

Originally Posted by MuttGrunt

If you only do very aggressive correction stages and you leave the car in the sun / outside non-stop, you'll be on the low end of how many times the car can be polished. If you do a heavy initial correction and then care for her properly so that only light work needs to be done in the future, you can have many many (12-18+) polishing sessions easily.

ouch. that doesn't seem like much in the grand scheme of things.

i personally leave my car outside year round (as i'm sure many other people who live in the city do). it's exposed to the sunlight all the time.

worst case scenario, i get 12 medium/light polishes out of it according to your estimate. that means if i do maintenance on the clearcoat twice a year (unavoidable, really). i'll only get 4-6 years out of my paint, depending on if there are some panels i need to go over 3-4x a year due to scuffs from people parking, brushing up against my car, or natural debris marring the paint.

does this sound accurate?

[MuttGrunt]

Originally Posted by tofu-

ouch. that doesn't seem like much in the grand scheme of things.

i personally leave my car outside year round (as i'm sure many other people who live in the city do). it's exposed to the sunlight all the time.

worst case scenario, i get 12 medium/light polishes out of it according to your estimate. that means if i do maintenance on the clearcoat twice a year (unavoidable, really). i'll only get 4-6 years out of my paint, depending on if there are some panels i need to go over 3-4x a year due to scuffs from people parking, brushing up against my car, or natural debris marring the paint.

does this sound accurate?

Sounds accurate if you're talking about a Porsche maybe. If your referring to an E90 series vehicle that has a much thicker paint system on it (well...nearly anything is thick compared to Porsche's), you'll be more than fine. Light polishing might only remove 1 or 2 microns. If you're talking about a final polish type step, it will likely be much less. The sun plays a factor in all this only because, from what I understand, the UV ray inhibitors that are in clear-coat naturally migrate towards the top (outer-most) area. So removing the first half of the clear-coat is more detrimental than if you could magically remove the second half instead.
I'm trying to talk about absolute worst case scenario after all, so take that into account. Maintain your case correctly and you can be looking at several dozen polishes prior to having to worry.

[BMWsky]

Awesome thread, I was wondering about this myself. Like most, I'm a hobbyist and use a PC. Good to know I can do 2 complete details a year on the car and not worry for a long while.

[tofu-]

Originally Posted by MuttGrunt

Sounds accurate if you're talking about a Porsche maybe. If your referring to an E90 series vehicle that has a much thicker paint system on it (well...nearly anything is thick compared to Porsche's), you'll be more than fine. Light polishing might only remove 1 or 2 microns. If you're talking about a final polish type step, it will likely be much less. The sun plays a factor in all this only because, from what I understand, the UV ray inhibitors that are in clear-coat naturally migrate towards the top (outer-most) area. So removing the first half of the clear-coat is more detrimental than if you could magically remove the second half instead.
I'm trying to talk about absolute worst case scenario after all, so take that into account. Maintain your case correctly and you can be looking at several dozen polishes prior to having to worry.

that is good to hear. I use po85rd pretty often due to a combination of washed induced marring, people leaning on the car, garbage bags in the street leaning on the car, etc. Hell, even a dry leaf blowing across my hood would probably scratch it.

[driverman]

IF I was retired and had money to play with, it would be interesting to do the following and post the results.

- Pick up a dozen hoods at junk yards from different types of cars in different condition that would be somewhat representative of what's out there.
- Purchase a high quality PTG that shows the thickness of all three layers of paint.
- Divide every hood into sections.
- Ask a pro detailer to supervise the process to make sure we use correct techniques.
- Measure and record paint thickness before and after a pass of the most popular heavy cutters (105, PG, etc.) with aggressive pads and a PC, Flex DA and a rotary.
- Do the same for medium cutters (205, SIP, etc.) and pads.
- Do the same for light cutters (106FA, etc.) and pads.
- Do the same for very light cutters and pads.

Then we'd know how much clear coat is removed by different polishers, polishes and pads on different types of paint.

I'd also build a database of clear coat thickness on a wide range of new and used cars. I'd then summarize and share the results.

[MuttGrunt]

Very nice idea driverman, but still not as useful as you might hope. Factors like temperature and humidity along with pressure also play a factor. Then lets take into account thickness measurements can vary with the temperature of the paint's surface, or the temperature of the metal underneath, or any of the layers covering the metal. So you'd also need to polish in a truly and completely climate controlled area.

In the end, you don't want to go off some book or list, regardless of who wrote it or co-signed for it. You need to use your own eyes to evaluate what's going on with your particular surface. You need to have tools that allow you to make the correct choice for what you have in front of you.

[driverman]

Originally Posted by MuttGrunt

Very nice idea driverman, but still not as useful as you might hope. Factors like temperature and humidity along with pressure also play a factor. Then lets take into account thickness measurements can vary with the temperature of the paint's surface, or the temperature of the metal underneath, or any of the layers covering the metal. So you'd also need to polish in a truly and completely climate controlled area.

In the end, you don't want to go off some book or list, regardless of who wrote it or co-signed for it. You need to use your own eyes to evaluate what's going on with your particular surface. You need to have tools that allow you to make the correct choice for what you have in front of you.

i agree that it would be impossible to develop an exact guide, but us newbies to paint correction need general guidelines to help us get started, even if they are rough and include ranges. This is especially true given the consequences of failure. Once we gain experience, we won't need it.

The same applies to any field. Good articles, books and teachers can give us a base of knowledge but we need experience to go to the next level. That's why I'm glad you are going to write your article. It's articles like yours that helped me "make the plunge" into this area.

[TOGWT]

Originally Posted by driverman

I've been researching clear coat thickness and the effects of paint correction. Here's what I've found:

- New cars come with 100-180 microns of paint, including primer, color and clear coats.
- The clear coat is 35-50 microns.
- Most auto manufacturers recommend that a maximum of 8 microns of clear coat be removed to leave enough clear coat to protect the color coat against UV damage. One article suggests 12 microns can be removed.
- Light compounding removes 1-2 microns.
- Heavy compounding removes about 3 microns.

Given all of that, a new car can handle 3-4 heavy compoundings over its life. If we work on our own car that we bought new, we'll know the history of the car (unless it was damaged and repaired before we took delivery). But if we work on someone else's car or a car we bought used, we won't know the history of the car. Therefore, doing a moderate or major paint correction without a paint thickness gauge (PTG) seems risky.

What do the pros think? They've learned from experience. Are these numbers about right? Is it risky to do medium to heavy compounding on a car without a PTG? If more clear coat is removed than the guidelines above, we'd never know it for sure without an expensive PTG that shows the depth of all three paint layers, right? We might suspect that's happened if the overall readings are low (<100 microns), right? If that happens, will vigilant waxing/sealing protect the remaining the clear coat and color coat?

Many thanks.

Clear Coat Thickness and Paint Removal by Polishing - http://www.autopia.org/forum/guide-d...polishing.html

[driverman]

Originally Posted by TOGWT

Clear Coat Thickness and Paint Removal by Polishing - http://www.autopia.org/forum/guide-d...polishing.html

Wow. Thanks for posting.

Do you know what the maximum clear coat reductions Japanese and European manufacturers allow before the paint warranty becomes void?