measuring tools and how too

[eddo]

Hey everyone, like many new detailers I would like to know what everybody uses to measure clear coat paint on a car before using any type of compounds or polishes. Can some educate a lot of us on what gauges you use and how to read it. What can you do with an example measurement, when it isn't a good idea do to any kind of paint correction ext. This information would be great. Thanks guys!!!

[greg0303]

Re: measuring tools and how too

These two articles provide some good info:

http://www.defelsko.com/applications...aint-meter.htm

http://www.defelsko.com/applications/paintmeter/automotive-paint-detailing.htm

I personally use HighLine II Meter by Elcometer (it gives solid readings in mils and microns):

[Michael Stoops]

Re: measuring tools and how too

Unless you spend huge sums of money on a paint thickness gauge, you'll only be getting a reading of the overall thickness of all layers - primer, base coat, clear coat - in one number. This is basically fine if you're working with factory paint since most factory paint uses something on the order 2 mils of clear coat, which should be the only thing you're working on anyway. If you take several readings on several body panels of a given vehicle you should have some pretty good consistency in those readings, assuming you're dealing a factory painted car. What a PTG like the one Greg shows can help you with (and by the way, the one Greg is using is often considered one of the best "bang for the buck" gauges) is finding areas where the paint reading is thin compared to the rest of the vehicle. This can be an indication that an area has been heavily cut in the past, perhaps to remove a deep scratch. It can also tell you if an area is especially thick, which is often an indication of a repainted panel - it is rare that a panel is stripped to bare metal in a collision shop prior to being repainted.

Another way that a PTG can help is when you're getting into some very aggressive processes, like wet sanding and rotary compounding. Say, for example, you've taken a wide selection of readings and you're consistently getting 6.0 to 6.3 mil readings. OK, so you know the paint is pretty uniform over the entire car, and with a reading in the 6 range you can be pretty confident that you've got the full load of factory paint to work with. So that also means you've got about 2 mils of clear to play with, as a general rule of thumb (it seems that clear coats are getting a bit thinner as paint tech continues to advance). Now, knowing that almost all manufacturers will tell you that if you remove more than 0.5 mil of clear you must repaint the car, you now have a good feeling for how much paint you can actually take off and still be safe. Obviously you don't want to approach that 0.5 mil max if you can avoid it - doing so means, basically, that this is the only time you can "cut" that car in an aggressive manner. Do it again and you've exceeded that manufacturer recommended limit and you're setting up for premature clear coat failure. But if you wet sand and find your readings are now in the 5.8 to 6.1 mil range, you're doing OK for that step. Compounding with a wool pad and M105 or similar on a rotary could take off close to that again, depending on your skill level.

On your own vehicles, especially if you're keeping them for a very long time, it might not be a bad idea to keep some historic data so you can tell over time how much paint you've taken off. We've said it many times in the past and we'll repeat it again - if you find you're having to remove swirls a few times a year and are concerned that repeated corrections are removing significant amount of paint over time, we want to know why those swirls are constantly coming back to such a degree. Sure, over time they're almost inevitable, but "time" shouldn't be every 3 or 4 months. Still, it would be interesting to see readings taken on the same, well cared for car over a period of a decade to see what's happened.

[eddo]

Re: measuring tools and how too

thanks mike. from mi initial understanding i thought a paint gauge would read the thickness of any cars clear coat. although it might me expensive for some of us i think a paint gauge is a necessary tool for this profession when having to do some major paint correction and not wanting to damage the customers car

[Michael Stoops]

Re: measuring tools and how too

Most paint thickness gauges will read the overall film thickness - primer, color, clear - that has been applied to the base metal substrate. It's not until you get into really expensive units that you can start reading individual layers. So when working on factory paint and using a paint gauge we are really going on the assumption that we have 2 mils of clear to work with as that is fairly standard in the industry. On a respray you can often find some pretty high thickness numbers since body shops don't always take a panel down to bare metal before repainting. So a reading of, for example, 12 mils is probably a good indicator that the pane was resprayed somewhere along the line, but it's no indicator of the actual clear coat thickness. And that's where things can be tricky: you can have a lot of overall film thickness but still have hardly any clear at all.