Reading and assessing PTGs

[Bullitt AK]

i know that when using a PTG mainly what i am looking for across the car is consistency and if there are spot fluctuations then make adjustments accordingly...

however say across the board the paint is pretty consistent...since all manufacturers have different thicknesses how do i know what reading is safe to polish at?

and generally how much paint is removed with light or heavy polishing and what is a safe level for the paint to be at after polishing without compromising the clear for later polishing?

thanks

[Mike Phillips]

Most of the "factory" paint I've measured and then either buffed or sanded and buffed as been between the range of 6.0 mills to 8.0 mils.

For example the hood my be, 6.2 - 6.4 - 6.5 - 6.2

So you can see the range is in the 6.0+ range. Assuming, and that's the big risk factor, that the clear is approximately 2.0 mils of the total film build, I've always been told you can safely remove about .5 mils

The assumption afterwards is that if the car is then "properly maintained" over the service life of the car, (how many people properly maintain their car's finish over the service life of the car), then the paint will last over this time period.

A Friend of mine who is a consultant to auto manufactures told me that testing has shown that a minimum of 1.3 mills of clear over the basecoat is necessary to prevent the basecoat from failing. (His words paraphrased).

The goal is always to use the least aggressive product to get the job done because in so doing you remove the unwanted defects while leaving the most amount of paint on the car.

At some point you're still going to come to a Go or No Go decision and the first thing I do and the first thing I teach in any class I teach is to first, "Evaluate the Customer" and then "Evaluate the finish".

Most polish manufactures teach you to evaluate the finish but I like to be a little more pro-active when accepting or declining a job because there are some people you don't want to work for because no matter how good or great you are, (or at least think you are), and no matter if you use the best products ever invented, you just can't make some people happy and for instances like these you need to know when to walk away.



:)

[Bullitt AK]

Thanks Mike, that was a much better reply then i had even hopped for.

if your'e assuming that the clear is 2 mils and that you can safely take off .5 putting the clear at 1.5 and it needs 1.3 to protect the base then all that could be removed in the future while still protecting the base is .2mil?

and say the total thickness average is less than 6 mils on average across the board...say its anywhere from 4-5.5? IYO you would not use any abrasives on it?
or if the PTG reads say 5.5 you would assume that only 1.5mil of clear is left?

and i have seen some reviews on here that warrant taking 2-3 hours with a PTG doing 2 inch spots or so at a time...this seems excessive to me and especially for anyone not doing high end vehicles...roughly how many measurements per panel is sufficient?


and how would mils convert to the 1xx numbers that you would usually see? how much of a fluctuation in mils is considered consistent? no more than .5 mils or so?

thanks again

[Mike Phillips]

Thanks Mike, that was a much better reply then i had even hopped for.

if you're assuming that the clear is 2 mils and that you can safely take off .5 putting the clear at 1.5 and it needs 1.3 to protect the base then all that could be removed in the future while still protecting the base is .2mil?



If I'm understanding you correctly then theoretically "yes".



and say the total thickness average is less than 6 mils on average across the board...say its anywhere from 4-5.5? IYO you would not use any abrasives on it?


No. You could have paint that reads 4.0 mils and it's possible that 2 mills are the clear layer. In order know this would need a really good paint thickness gage. This also reverts back to what I wrote about


Evaluate the customer
Evaluate the finish



What are you working on?
What are you trying to do?


If you have a customer that wants you to wetsand their factory finish to remove the orange peel and you can tell they're picky I'd have already turned the job down and now I don't have to care about how thick the clear is. Don't make detailing cars harder than it has to be.



and i have seen some reviews on here that warrant taking 2-3 hours with a PTG doing 2 inch spots or so at a time...this seems excessive to me and especially for anyone not doing high end vehicles...roughly how many measurements per panel is sufficient?


Considering how long it takes to do a "Complete", (my term for a full-on compound, polish and wax job by machine to a horrific finish), then yes, taking even more time to measure every few inches is excessive because you've past the point of being practical. If a person is that scared of ruining the paint due to thinness, turn the job down and take something that you feel comfortable with.



and how would mils convert to the 1xx numbers that you would usually see? how much of a fluctuation in mils is considered consistent? no more than .5 mils or so?
thanks again


I don't ever get that deep, before I get that deep I've first either decided to work for the customer or not, and then I've made the Go or No Go decision and if I decide to buff out the car I'm probably taping things off by this time.


What are you working on? Or is this all just hypothetical? I've engaged in both hypothetical threads and real-world threads as long as anyone in the forum world and hypothetical threads are great but having a real car in the garage is where the rubber hits the road.


:)

[Bullitt AK]

Evaluate the customer
Evaluate the finish



What are you working on?
What are you trying to do?


If you have a customer that wants you to wetsand their factory finish to remove the orange peel and you can tell they're picky I'd have already turned the job down and now I don't have to care about how thick the clear is. Don't make detailing cars harder than it has to be.
:)

yes this is all hypothetical however im not doing anything like wetsanding, just basic paint correction/swirl removal and i wanted to be on the safe side, great info thanks alot

[Mike Phillips]

yes this is all hypothetical however im not doing anything like wetsanding, just basic paint correction/swirl removal and i wanted to be on the safe side, great info thanks alot


No problemo... it's good to think things through...

If you're working on your car of course you want to be careful and if you're working on a customer's car then you for sure want to be careful.. and for what it's worth... hundreds of thousands of us have been machine buffing out our cars and customer's cars for decades and problems from removing too much material is the exception, not the norm.

Fact is most people struggle with removing swirls and scratches, especially when they first start out. Another way of saying this is,

Most people struggle with removing enough paint...


Just stick to safe tools, safe pads and safe products and find someplace where you can get trustworthy information...


Autogeek is always here to see you through to success...


:xyxthumbs:

[mcpp66]

Hey Mike, speaking of clear coat thickness.........I've heard people say that in order to roughly determine the thickness of your clear you can measure the door jamb and subtract that from the measurements on your other panels. I don't think I've ever heard your opinion on this.......that does seem to make sense and I've gotten that from some good people on this board. However, I like to hear your opinion on these things as well. Thanks.

[Bullitt AK]

Hey Mike, speaking of clear coat thickness.........I've heard people say that in order to roughly determine the thickness of your clear you can measure the door jamb and subtract that from the measurements on your other panels. I don't think I've ever heard your opinion on this.......that does seem to make sense and I've gotten that from some good people on this board. However, I like to hear your opinion on these things as well. Thanks.

i would be interested in knowing also however i have heard that on some vehicles the clear is not applied as thick in the jambs

[mcpp66]

i would be interested in knowing also however i have heard that on some vehicles the clear is not applied as thick in the jambs

It's my understanding that they spray much less clear coat in the jambs. I posted a question about this a while back because I wasn't sure if the base coat thickness can be considered consistent throughout, because if otherwise then this measurement would be meaningless. What I was told was that the base coat is generally consistent throughout in order to maintain color consistency and that the clear in the door jamb area is so thin that it's almost negligible (my words, not the words of the person who told me this, so if that's an inaccurate statement someone please correct me). Therefore, you can get a rough, but decent, idea of how much clear you have.

[Bullitt AK]

i would think for that statement to be true you would need to know from the factory roughly how much less clear they use in the jambs because some clear could have already been removed from the finish

[mcpp66]

i would think for that statement to be true you would need to know from the factory roughly how much less clear they use in the jambs because some clear could have already been removed from the finish

Well, remember that I've been using the term "rough estimate".

[RaskyR1]

The average coating thickness on my Acura is about 115-120 Microns (4.5 mil). The Door jambs are around 65-70 Microns (2.6 mil). I feel it does give you some idea but should not be set in stone.

[Mike Phillips]

Hey Mike, speaking of clear coat thickness.........I've heard people say that in order to roughly determine the thickness of your clear you can measure the door jamb and subtract that from the measurements on your other panels.

I don't think I've ever heard your opinion on this.......



I've heard or read things like this before but I would never use this approach, too risky...

One thing I try to do is

KISS - Keep it Simple Simon


I've always noticed on discussion forums the trend is to take something very simple and over-complicate it...


:)