# Paint depth gauge, waste of money?



## SystemClenz (Oct 31, 2008)

Help me out here, was thinking of buying one but then found out they don't measure the thickness of the top coat, so if the swirls are in the top coat how do you know how much you've got to play with?

Cars that have been repaired may have had any number of coats of paint and any number of coats of top coat so really you have no idea?

Please correct me if I'm wrong here


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## Mr Face (Jan 22, 2009)

A PDG is unfortunately essential Im afraid. Without it I and many others while polishing will have/could have compromised the paint or clear coat. 

Recently I have helped a new member on here with his Mazda Estate and without a PDG I would not have known it had the thinest paint / clear coat layer of any car I have ever detailed. At its thickest it was 80un and thinnest just 60un. Without knowing this we would have almost certainly gone with a wool pad and compound to correct the paint, thank god we didnt. We gave it two light hits to remove the majority of the wash marring and had to settle with the conclusion what's left stays. 

The alternative would have meant a respray if we had compromised what little paint it had. 

So, sorry fella, yes, if you are flattening a paint/clearcoat surface you do need to know what you are playing with.


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## Will_G (Jan 23, 2012)

If you're planning on doing any kind of correction a PDG is essential to at least give you an understanding of what you've got to deal with. As an hobbyist i've got the PD8 but some of the professionals out there have more sophisticated gauges which give you a breakdown of layers I believe.


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## SystemClenz (Oct 31, 2008)

But how thick was the clearcote? The surface you are machining? 

This is my main question? The paint could be 140 and the clearcote could be 40, or the paint 140 and the clearcote 5!, theres some dodgy body shops out there that do it very cheap! 

So how can you tell???

Thanks for your prompt reply.


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## SystemClenz (Oct 31, 2008)

Will_G said:


> If you're planning on doing any kind of correction a PDG is essential to at least give you an understanding of what you've got to deal with. As an hobbyist i've got the PD8 but some of the professionals out there have more sophisticated gauges which give you a breakdown of layers I believe.


To the best of my knowledge there's NO way of breaking down the layers, just from surface to metal.


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## Mr Face (Jan 22, 2009)

There are PDG's that measure each individual coat however, you need a mortgage to buy one.

With the single reading ones that most hobby detailers use clear coat finger in the air thickness is normally 25% of the total. 

HOWEVER : ive just done a brand new Raspberry Fiesta that had one door where colour bleed was obvious on a white hex pad. It felt totally different to polish (sticky) and had been resprayed and had ZERO clear coat. Not bad for a brand new car.


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## Foxx (Jul 5, 2011)

It is kind of essential if you are working on other people's cars, sadly. 

The best way to think of the benefit is not that it will give you a complete breakdown of the layers on the car, but more that it will a good way to get a rough plan of where to be a little more cautious. This is especially important if you have a car that you *think* would be thick, hard paint, but that has in fact been damaged and resprayed without the current owner being aware (or telling you). It's also the only way for you to know how much you have actually taken off the surface. If you know how much you will be able to take off before you start, you can set yourself a "point of no return" (just correcting until the swirls have gone is not always the best idea, as you will only know you have gone too far when you see paint on the pad).

It is always good practice to start on any car with the gentlest cut and work your way up anyway, but as you will never know the full and true history of a car's paint, a PDG can only help give you a bit more information before you start working.


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## Will_G (Jan 23, 2012)

MattWSM said:


> To the best of my knowledge there's NO way of breaking down the layers, just from surface to metal.


For example http://www.defelsko.com/p200/positector200.htm

Used on this thread

http://www.detailingworld.com/forum/showthread.php?t=262401


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## ted11 (Jul 8, 2011)

To get a rough idea I would normally measure a non clear coated part of the car ie under side of the bonnet and subtract from the reading on the outside .


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## SystemClenz (Oct 31, 2008)

ted11 said:


> To get a rough idea I would normally measure a non clear coated part of the car ie under side of the bonnet and subtract from the reading on the outside .


This must be tip of the day?

Thanks for your help on this one guys :thumb:


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## pawlik (May 16, 2011)

Personally, I polishing cars about 5-6 years without any PDG. Cars was in very different condition: from almost new to very old, after respraying or sanding... and i did only one failure, so for me PDG it really wasting money.


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## Ratchet (Dec 30, 2011)

Maybe hire one if its a one off.


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## waxy (Feb 27, 2006)

You may be told it's a waste of money getting one,in fact there's someone on here who has the unique ability to determine how much paint is on a car,just by looking at it:lol::lol:


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## -Raven- (Aug 26, 2010)

Mr Face said:


> A PDG is unfortunately essential Im afraid. Without it I and many others while polishing will have/could have compromised the paint or clear coat.
> 
> Recently I have helped a new member on here with his Mazda Estate and without a PDG I would not have known it had the thinest paint / clear coat layer of any car I have ever detailed. At its thickest it was 80un and thinnest just 60un. Without knowing this we would have almost certainly gone with a wool pad and compound to correct the paint, thank god we didnt. We gave it two light hits to remove the majority of the wash marring and had to settle with the conclusion what's left stays.
> 
> ...


Why the hell would you use wool on any Jap car, let alone soft Mazda paint?


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## -Raven- (Aug 26, 2010)

Just remember PDG's are just a guide, they won't stop burnt paint. I'd certainly invest in one if attacking other people's cars. For just your own car? Waste of money IMO. :thumb:


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## Nally (May 30, 2012)

Anyone used one of those snap guages ?


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## Mr Face (Jan 22, 2009)

-Raven- said:


> Why the hell would you use wool on any Jap car, let alone soft Mazda paint?


an 'analogy'


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## -Raven- (Aug 26, 2010)

Mr Face said:


> an 'analogy'


"almost certainly gone with....."

Why would you even think about using wool on these cars, Even without thin paint? As I said before, PDG's won't stop people burning paint.


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> Just remember PDG's are just a guide, they won't stop burnt paint. I'd certainly invest in one if attacking other people's cars. For just your own car? Waste of money IMO. :thumb:


sorry i dont agree even if its just for your own car they are worth the money. people spend well over £100 for a wax and a fortune on a da/rotary pads polishes etc,but the 1 thing that gives you a guide to what paint you have to play with seems to be to expensive, but not as expensive as having it resprayed. dont make sense to me to be without 1


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## -Raven- (Aug 26, 2010)

cheekymonkey said:


> sorry i dont agree even if its just for your own car they are worth the money. people spend well over £100 for a wax and a fortune on a da pads polishes etc,but the 1 thing that gives you a guide to what paint you have to play with seems to be to expensive, but not as expensive as having it resprayed. dont make sense to me to be without 1


why? So you can attack it with wool because you 'think' it's safe to do so?


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> why? So you can attack it with wool because you 'think' it's safe to do so?


who said anything about wool ?
I have never seen the need for wool
i know exactly wht the thickness of my paint is do you? but i bet you have paid virtually the price of one on a wax now that dont make sense imo


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## -Raven- (Aug 26, 2010)

cheekymonkey said:


> who said anything about wool ?
> I have never seen the need for wool
> i know exactly wht the thickness of my paint is do you? but i bet you have paid virtually the price of one on a wax now that dont make sense imo


I bet you don't know exactly!  I got a PDG, they are just a guide. 

Who said about wool? Mr Face. People read these threads and think it's fine to go attacking the paintwork. :wall:

As for having your own PDG for your own car? How many times do you seriously compound/polish your own car?


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> I bet you don't know exactly!  I got a PDG, they are just a guide.
> 
> Who said about wool? Mr Face. People read these threads and think it's fine to go attacking the paintwork. :wall:
> 
> As for having your own PDG for your own car? How many times do you seriously compound/polish your own car?


then may as you say be a guide but that depends on the paint but i am sure a guide is better then a guess. 
I would say the majority of people on here have a second hand car like i do and its not just the amount of compounding/polishing you do yourself it the history before you got it that the problem. is your car new or used when you got it


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## -Raven- (Aug 26, 2010)

cheekymonkey said:


> then may as you say be a guide but that depends on the paint but i am sure a guide is better then a guess.
> I would say the majority of people on here have a second hand car like i do and its not just the amount of compounding/polishing you do yourself it the history before you got it that the problem. is your car new or used when you got it


ok then, use it once then throw it away! 

Or better yet, just pop down to a pro and use theirs.


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> ok then, use it once then throw it away!
> 
> Or better yet, just pop down to a pro and use theirs.


so you have never used yours on your own car


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## -Raven- (Aug 26, 2010)

cheekymonkey said:


> so you have never used yours on your own car


Only once when I brought it brand new. I don't get it out for every time I use a pre-wax cleaner and wax. It'll never see a compounding, it'll be lucky if it sees a light polish every year or two. As I said, waste of money just for your own car IMO. :thumb:


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## Mr Face (Jan 22, 2009)

Gentlemen, please let me apologise for a poor choice of words, I have no wish to wind anyone up, start a debate or blood bath, all that negative energy is saved for my ex.

I will however make sure my thoughts are put into print with more thought next time. 

I do believe though that a paint depth gauge is not a nice to have when flattening any paint/clearcoat surface and as my previous PDG gave up the ghost recently I will be reviewing what I believe is a new entry level one from our friends in Germany very soon. It will also be with Lee at Bespoke in Shrewsbury on Saturday should anyone fancy a touchy feely with it. 

Again, apologies for leaving what small amount of grey matter I have left in reverse.

Mike :thumb:




p.s. that is entry level in terms of cost, not quality or functionality.


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## bizzyfingers (Jul 30, 2009)

ted11 said:


> To get a rough idea I would normally measure a non clear coated part of the car ie under side of the bonnet and subtract from the reading on the outside .


AMAZING tip!


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## -Raven- (Aug 26, 2010)

bizzyfingers said:


> AMAZING tip!


Common knowledge? Door sill easier too. :thumb:


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## Marky-G-66 (May 31, 2012)

I wouldnt be without my PTG, in fact i bought mine before i bought a polisher...
Do friends, family, neighbours and my own car of course and i wouldnt dream of not having a "measure" of the paint before polishing... but using just a PD8 does have limitations which does put me off putting polisher to paint sometimes. My own car has reading of between 85 to 140 depending on the panel which gives me an idea of what im working with but what about the rest of the car??? On most cars the front and rear panels are plastic as is the removable hard top on my car...PD8 no good on these areas...So i suppose its a case of just guessing and hoping the reading on these panels are the same as the steel panels Which is not really the best way to go...So should i not Attempt to polish these areas ???......I only use finising polishes on these areas and would never attempt to correct any deep scratches on these (id be too scared too:lol... so unless i pay£???? for a Defelsko (for example) its only ever going to be guesswork for say 1/3rd of the car...
I suppose its all about gathering as much information about the paint as you can to be as safe as you can and having A PD8 helps with that a lot...


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> Common knowledge? Door sill easier too. :thumb:


so they do tell you how much clear coat you have :thumb:


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> Only once when I brought it brand new. I don't get it out for every time I use a pre-wax cleaner and wax. It'll never see a compounding, it'll be lucky if it sees a light polish every year or two. As I said, waste of money just for your own car IMO. :thumb:


 you tell people not to bother with 1 for there own car as there not worth it and are only a rough guide and wont stop you burning through, yet you use one on your brand new car you know theres enough paint on a brand new car it has no history:thumb:


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## Nanoman (Jan 17, 2009)

MattWSM said:


> Help me out here, was thinking of buying one but then found out they don't measure the thickness of the top coat, so if the swirls are in the top coat how do you know how much you've got to play with?
> 
> Cars that have been repaired may have had any number of coats of paint and any number of coats of top coat so really you have no idea?
> 
> Please correct me if I'm wrong here


I'm not sure how much has been said in this thread because I have only read the first few posts on page 1...

You're right a PDG won't tell you the thickness of the top coat.

A PDG will give you a good indication of:
1) removal rates
2) low spots
3) smart repairs
4) panels with non-factory paint.

If you're planning on doing other people's cars I'd say you're wreckless if you don't use one. If you're just doing your own and don't care if you end up needing a respray then fill your boots.

There are people that (arguably) have enough experience to know what they can do without a PDG but they are few and far between and have generally have many years experience with a machine polisher.

Edit: I've read the rest of the thread.
That bit about measuring bonnets and doorshuts... I'm not sure that's relevant on modern cars.
The bit about a PDG being a waste of money if you are only doing your own car and won't go near it with anything other than a finishing pad and paint cleanser... absolutely correct. If you're not 'polishing' then you don't need a PDG.


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## -Raven- (Aug 26, 2010)

cheekymonkey said:


> so they do tell you how much clear coat you have :thumb:


Nope! Good guess at best.


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## -Raven- (Aug 26, 2010)

cheekymonkey said:


> you tell people not to bother with 1 for there own car as there not worth it and are only a rough guide and wont stop you burning through, yet you use one on your brand new car you know theres enough paint on a brand new car it has no history:thumb:


Did you even read what you quoted?

Yes I used my PDG on my new car once out of interest, it told me nothing I didn't already know just by inspecting the paint. Yes, I still think PDGs are a wast of time if you are only going to use it on your own car.

I don't see how that can be confusing? Door handles and light switches must keep you amused for hours! :lol:


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> Did you even read what you quoted?
> 
> Yes I used my PDG on my new car once out of interest, it told me nothing I didn't already know just by inspecting the paint. Yes, I still think PDGs are a wast of time if you are only going to use it on your own car.
> 
> I don't see how that can be confusing? Door handles and light switches must keep you amused for hours! :lol:


yea i read it,its how you contradicted what you said its not that hard to understand but to help i,ll try and make it easier for you to understand:thumb:
your telling people a pdg is a waste of money if its for there own car as it doesnt tell you how much clear coat/paint there is on there second hand car which obviously has history to the paint they dont no about. yet on your own brand new car you used a pdg on virgin paint , i think you will have to agree second hand paint with unknow history is more susceptible to strike through then brand new paint.:thumb:


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> Nope! Good guess at best.


no guessing involved its simple clear coated paint - no clear coated paint = clear coat thickness  :thumb:


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## cheekymonkey (Mar 15, 2008)

[QUOTE=-Raven-;3655060
Yes I used my PDG on my new car once out of interest, it told me nothing I didn't already know just by inspecting the paint. 

yes it did it told you the thickness of the paint, or are you trying to tell us you can see how thick paint is by inspecting it  like to see you know the thickness of second hand paint by looking at it, wait you could hire you self out as the human pdg. i can see it now is it a bird, is it a plane no its PDG MAN :lol::lol::lol:


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## cheekymonkey (Mar 15, 2008)

waxy said:


> you may be told it's a waste of money getting one,in fact there's someone on here who has the unique ability to determine how much paint is on a car,just by looking at it:lol::lol:


  :thumb:


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## Frans D (May 23, 2011)

I completely agree with Nanoman.

Further more a lot of car paints are nowadays painted wet on wet, so the colored and the clear coat will merge into eachother. 
In such cases even with pdg's which are ment to measure multiple layers, you cannot check how much clear coat you have on such a car.

Also measuring removal rates is very difficult.
You have to measure again and again at the exact same spot as the total thickness can be quite different just a little bit further away.
To do this you really need a laser pen or so in a fixed position.

I use my pdg only to check for areas that need extra attention (2,3 and 4 of Nanoman) and in that it already helped me out on several occasions.

If I would do only my own car, I would never have bought one and asked if a detailer in my area could measure my car.


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## cheekymonkey (Mar 15, 2008)

I would think there are quite a few ppl who decided not to get a pdg and when the did strike through the first thing they thought was they wish they had bought a pdg as there cheaper then a respray


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## Ross (Apr 25, 2007)

Cheaper than having to respray a panel.


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## cheekymonkey (Mar 15, 2008)

Ross said:


> Cheaper than having to respray a panel.


:thumb:


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## moosh (May 8, 2011)

waxy said:


> You may be told it's a waste of money getting one,in fact there's someone on here who has the unique ability to determine how much paint is on a car,just by looking at it:lol::lol:


:lol: there are some people on here that can't read :thumb:


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## moosh (May 8, 2011)

cheekymonkey said:


> no guessing involved its simple clear coated paint - no clear coated paint = clear coat thickness  :thumb:


They use a matting agent on areas under the bonnet and boot that's added to the clear from the factory :thumb:


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## cheekymonkey (Mar 15, 2008)

moosh said:


> They use a matting agent on areas under the bonnet and boot that's added to the clear from the factory :thumb:


not all do :thumb:


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## -Raven- (Aug 26, 2010)

cheekymonkey said:


> yes it did it told you the thickness of the paint, or are you trying to tell us you can see how thick paint is by inspecting it  like to see you know the thickness of second hand paint by looking at it, wait you could hire you self out as the human pdg. i can see it now is it a bird, is it a plane no its PDG MAN :lol::lol::lol:


I'll play nice and share some tips to you since you think PDG's are the be all and end all, and you'll die without one...

It's not hard to inspect the paint. Look at the orange peel. If there's panels that are different, take a closer look. If one side of the car has flatter orange peel than the other, it's likely there has been a repair or respray. Take a closer look...

It's not hard to pick a resprayed panel, especially metallic, if you just look...

It's not hard to comprehend that the clear coat on a car is about 1/3 - 1/2 the thickness of a sheet of A4 photocopy paper. Remember this and it might just stop you doing dumb s***...

Water based paint systems (Japanese cars) are getting softer and softer due to the lack of hardener. Remember this and it just might stop you doing dumb s***...

Last but not least, it's not hard to ask the previous owner (if you got second hand car) about the history of it. Has it had any resprays? Has it been polished before?...

As I said before, if you are that worried about it, you could pop down and borrow a pro's PDG for that once off event. It'll just confirm what can already see... :thumb:

So, you got a PDG? Do you know how to use it? Do you know how to interpret the readings? Do you know how much paint removal is safe? There's a lot more than just having a PDG...

Now more on why I think it's a waste of time *just for your own car*.
How many times are you going to compound the crap out of it? Seriously? Once the paint is in good condition, you don't polish the crap out of it again, do you? You might use a finishing polish to clean up wash haze and restore clarity once or twice a year, but do you know the removal rates for a polish like Menzerna 85RD, even on soft paint? I know I could polish both my cars tons of times with 85RD and still be left with what is considered safe clear coat thickness left. Even on my thin, sticky, crap, Honda paint. :thumb:


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## RedUntilDead (Feb 10, 2009)

Play nice Raven cheekymonkey is an informative poster, well most of the time
I can see both sides of the coin but Raven really does have a point. I used my ptg on my own brand new car once when I first washed it. It only ever comes out when I work on other peoples cars and even then It takes common sense in use i.e I dont take its readings as gospel. Not everyone is honest if you ask them about previous repairs either!
When people use these things are they measuring at the exact same point every time? no. Are they measuring the panel at the same ambient temp? I bet not.
Off topic a bit but its shocking how thin the paint is on the new cars I have come across, I wont be rushing into compounding my own bm, fillers all the way!


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## Frans D (May 23, 2011)

Tbh; most screw ups regarding striking throughs I've seen, were due to people lacking experience in paint correction.
Would a PDG have saved them? Probably not, because a PDG won't assist you in handling a machine correctly and choosing the right working methode, products and pads.

Can it assist you in a more secure paint correction? I would say yes. 
I'm not in the "I can see exactly how much clear coat I have and how much I am removing" camp.
Neither am I in the "I can see everything what's wrong with the paint, by visual inspection and experience from the past" camp.

I'm kind of in middle of that;

1) I am aware, it is close to impossible to check with a normal PDG how much clearcoat I have and how much I am removing.
(_theoretically you can, but it is so much of a hustle during a normal detail with fixed laser dots etc. and still you don't remove an exact even coat over the complete surface, as you are not a robot_)

2) In a lot of cases you can't determine the condition of the cars paint just by visual inspection; 
a) A real good (spot or panel) damage repair is almost impossible to see visually.
b) In case of a complete overspray, it is much easier to find bondo spots with a PDG as with the "knock on wood" methode.
c) Paint correction done by others and especially corrected damaged areas (kind of a spot repair, only done by compounding).
etc.

Underneath some examples out of my own situation;

A Jaguar, which had two repaired panels (one of them on the pic at the right front).










One at the left back and one at the right front.
The one at the back was a bit of a mess (orange peel, dust particles) and easily to discover by eye, the one at the front however wasn't visible by eye. It was a perfect repair and it looked just as the rest of the factory paint.
So I had 3 paints with different hardnesses and by doing just a test spot on the factory paint, I would have had 3 different removal rates.
Meaning that I would have removed more coat of the softest paint, if I had used the same working methode over the complete car.

A classic Mercedes which was restored (many) years ago;



















The condition of the paint was very bad and to correct it, it needed to be heavily compounded. However the PDG gave dramatic readings, pointing on the fact that on a lot of places there was a lot of bondo present.
So having my paint (more bondo in this case) mapped, I could exactly see were I could work with less and more danger and choosing the save way, by removing overall less paint as I planned by the upfront visual inspection.

I haven't got pics of my last example; but it was a Chevrolette Matiz of one of my neighbours. A backdoor was scratched by a shopping cart and the dealer gave her a several hunderd Euro's quotation to repair it.
She asked me if I could take a look at it and if I couldn't do anyting with it she would let it repair.
So I went at that door, with the knowledge that I could do a high removal rate (nothing gained, nothing lost).
I got the door looking almost perfect again and she was very happy with it.
However if she would sell the car and another detailer would have a go with the (soft painted) car, he would never know without a PDG, that the door has less paint as the other panels.

Just my 2 cents, no personal attacks intended. :thumb:

WKR Frans


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## Nally (May 30, 2012)

Anyone use a snap guage


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## zackruncie (Oct 15, 2011)

tbh there is a lot of debate of the pdg but in my opnion it is a very handy piece of kit as it allows you to see the condition of the paint before you start and can help stop problems arising


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## PJS (Aug 18, 2007)

MattWSM said:


> Help me out here, was thinking of buying one but then found out they don't measure the thickness of the top coat, so if the swirls are in the top coat how do you know how much you've got to play with?
> 
> Cars that have been repaired may have had any number of coats of paint and any number of coats of top coat so really you have no idea?
> 
> Please correct me if I'm wrong here


Completely wrong!
You do realise (obviously not really) that it's not measuring the pigment layer, but everything applied on top of the metal substrate?
That's your primer/anti-rust treatment, the paint colour layer, and the clearcoat (which could include a pearl layer below it if a 3 stage paint process).
The difference in reading between the panel and the door frame or under the bonnet chassis reading, is the thickness you've got to work with.


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## PJS (Aug 18, 2007)

-Raven- said:


> Why the hell would you use wool on any Jap car, let alone soft Mazda paint?


That's why - http://www.detailingworld.co.uk/forum/showthread.php?t=133763


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## moosh (May 8, 2011)

cheekymonkey said:


> not all do :thumb:


I do appreciate that bud, was just adding some info to the debate.

Since the last heated debate about PTG I came away from that with some good information and these debates are great and ok they can get heated but that healthy.


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> I'll play nice and share some tips to you since you think PDG's are the be all and end all, and you'll die without one...
> 
> It's not hard to inspect the paint. Look at the orange peel. If there's panels that are different, take a closer look. If one side of the car has flatter orange peel than the other, it's likely there has been a repair or respray. Take a closer look...
> 
> ...


well thank you for the tips raven but its nothing i dont already know, ive been useing a pdg for over 17 years and as for jap paint i,ve owned my gallant for 8 years. 
but now to the truth i'm answering the op's question and looking at it from his side, meaning hes new to it not experienced. Its a totally different ball game when your new to it, so is a pdg a good idea for him? hell yes it is he doesn't know how to read paint or the tricks like under the bonnet.
think back to when you first started you didnt know what you know now and most importantly the experience, that comes with time, and until someone reaches that level a pdg is essential imo:thumb:
when it comes to orange peel you have to remember that different machines spray different areas of the car so a difference in orange peel can just be from the set up of each machine and not a respray. if the orange peel is mainly in the colour coat then you will never get rid of it fully and can leave the impression there is more top coat then the really is. when it comes to previous owner unless there the same as us then anything about polishing will be useless information, polishing to most means turtle wax from halfords and a old rag.


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## cheekymonkey (Mar 15, 2008)

moosh said:


> I do appreciate that bud, was just adding some info to the debate.
> 
> Since the last heated debate about PTG I came away from that with some good information and these debates are great and ok they can get heated but that healthy.


yea mate i know just didnt want newbys thinking they all did :thumb:


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## Frans D (May 23, 2011)

PJS said:


> The difference in reading between the panel and the door frame or under the bonnet chassis reading, is the thickness you've got to work with.


I must disagree with this statement;
The paint coats are not consistent over all the panels and parts.
I never have measured an exact thickness of paintcoat over a complete car.
Besides that; a lot of painting robots also spray clear coat on the door frames.
Also knowing how much thickness the underside of a bonnet has, won't prove how much thickness the bonnet has on top without the clearcoat as it is sprayed in different momentums.

Overhere you can see an example of a clear coat application at the BMW factory; http://www.bmwusfactory.com/manufacturing/production-process/paint-shop/


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## cheekymonkey (Mar 15, 2008)

-Raven- said:


> Just remember PDG's are just a guide, they won't stop burnt paint. I'd certainly invest in one if attacking other people's cars. For just your own car? Waste of money IMO. :thumb:


? burnt paint has nothing to do with if you use a pdg or not. thats due to user error and will happen no matter what thickness your paint is:thumb:


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## stangalang (Nov 27, 2009)

Op, not sure what's been said already in the thread as I can't be arsed reading, but a ptg is essential in my opinion, to help you build a fuller picture of what is going on. Using visual notes, touch and feel, your ptg etc you can make mental deductions as to what is safe, normal and what should be treated with kid gloves. Any information you can find before polishing is a bonus, simple


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## RDB85 (Dec 28, 2011)

I done some machine polishing with a pro, and we never used a ptg. He was with me at all times, so that maybe why, but he did leave me on my own for a while to get the hang of machine polishing by myself. We used megs 105 and 205. But I know that he uses a very expensive Posi DFT and 6000, and has explained it all to me when we where doing the tuition course. 

I think the op best be would be to do a course first and ask the pro the best way to use the ptg, and explain every tiny detail in how to use them to their best ability. That way at least he can get a better understanding.

Would I get one for my own car, probably not, but if I where a offering it as a service I would certainly get the more expensive ptg


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## Hasan1 (Jul 1, 2011)

I would say if you have the money it's not a bad bit of kit. I got 1 of the GB on hear. Iv not just used it on detailing on my car it's also good to take with you if you know any 1 buying a second hand car as you can tell if it's had any repare work on it.


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## PJS (Aug 18, 2007)

Frans D said:


> I must disagree with this statement;
> The paint coats are not consistent over all the panels and parts.
> I never have measured an exact thickness of paintcoat over a complete car.
> Besides that; a lot of painting robots also spray clear coat on the door frames.
> Also knowing how much thickness the underside of a bonnet has, won't prove how much thickness the bonnet has on top without the clearcoat as it is sprayed in different momentums.


Trust me Frans, when you've measured enough cars, there's a generalisation that can be made and used across the board.
It's not 100% infallible - but it's a very good close approximation.
If you're looking for absolutes, then the only one in existence is to not polish paintwork, but just mask it and seal it.
As it is, many of us regularly polish paintwork without a problem, so we must be doing something right.

Funny you should mention BMW, since it was the very same company who started saving money by using less clearcoat in areas that were rarely exposed to the elements or seen high wear.


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## Mirror Finish Details (Aug 21, 2008)

-Raven- said:


> Why the hell would you use wool on any Jap car, let alone soft Mazda paint?


Why not?????
Wool is agressive but runs cool, I use wool every day for compounding on everything that comes in.

If you can use wool properly it does not leave marks, been using wool pads over 20 years.

Problem with the Positector 200 is it can read 3 layers as from the factory, if it has has a re spray it can only read the full thickness. Most of us know the the paint thicknesses on a new car anyway.


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## PJS (Aug 18, 2007)

In answer to the thread title's question - is a paint gauge a waste of money, you'd need to define waste.

1) A gauge will be worth a good percentage of its value second hand, so you'll have only paid for the time you've owned it.
2) If a respray of a panel or larger area through lack of knowledge that an area was already thin is considered easily affordable.
3) If the devaluation of your car from having been resprayed is of no consequence.
4) If you'll never tackle deeper RiDS

Bottom line, no-one is going to admire you more or less for having a paint gauge, and using it whenever you feel its warranted.
So buy one or don't buy one based on how you classify money wastage.


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