how many times can you use medium abrasive products w/o a risk of cc reduction?

A

andrew300

New member
i was wondering how many times you could safely detail a whole car by pc with medium abrasive products like ssr 2.5 or megs dacp without significant clear coat reduction. on some cars, this is the only thing that works on light swirls so i find myself using lots of coats on it and do not want to reduce the clear coat because most of the cars i detail are not mine.
 
Anytime you use an abrasive product you erode cc away. I think it really depends on how much clear there is to start with.

A paint thickness gauge is the only real way to be sure you are at a reasonable level.
 
now can someone answer this question. how does megs dacp remove all the swirls without removing any clear coat and not having any fillers in it?
 
manawar said:
now can someone answer this question. how does megs dacp remove all the swirls without removing any clear coat...
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Like any abrasive polish, DACP *does* remove some clear coat. At last year's St. Louis g-t-g an autopian with a PC and DACP/cutting pad cut through the clear on a Benz. Mike Phillips (from Meguiar's) was there, as I recall. It can happen.



Asking how many times you can polish without clearcoat failure is like asking how many times you can use a harsh toothpaste before you take off too much tooth enamel. Nobody can really say. More than a few, fewer than a lot; it "just depends".
 
ericssion- Griot's sells a digital paint gauge so I'm sure other places have them (and even cheaper). But a) they're all quite expensive, and b) unless you know how much paint is supposed to be on there (varies between makers and even between models, let alone what about repainted areas) it won't help all that much. The gauges don't differentiate between primer/basecoat/clear and it's the thickness of the clear you need to worry about. So I dunno if they'll help all that much.
 
is there a list somewhere of what the thickness of clearcoat should be for every specific car....i'd love to have something like that
 
The thickness of clearcoat is dependant:



1. Is it OEM? OEM finishes tend to be very thin.

2 Class of car? Rolls Royce wet sands their paint between each application and they apply many layers. So they'll have substantially thicker paint.



The general consensus is you can remove up to 0.3mil without compromising the clear. Using a SMR, you can polish 3-4x/year for 10 years and you should be find. When you start getting in compounds though, that's a different story. It's a product, pad, contact time thing. If you use Diamond Cut with a wool cutting pad, you can quickly compromise the clear if you don't know what you are doing.



Note 1: Paint tends to be very thin on edges as opposed to flat sections so you need to measure it's thickness throughout.



You also need to know if the paint you are dealing with is Single Stage, 2 Stage (Base/Clear), 3 Stage (Base, Candy, Clear) etc as each of those build up film but not necessarily clear! You need to know how many coats of clear exist and not necessarily, how thick the paint is.



If you watch some of the TV shows such as Rides, OCC, Great Builder Bike Off, you'll see that they often apply 3, 4, 5+ coats of clear on top of color coats (including Candy etc). Large scale car manufacturers do not apply it that way for costs reasons and probably >98% of all cars on the roard are 1 single clear coated.



Note 2: You can actually remove clear without seeing any adverse outcomes initially but end up with clear failure later because the upper 1/3rd of the clear contains all the UV-blockers etc. So cutting through the 1/2 the clear may produce great results to remove all the swirls etc. but in a couple of years time if the car is not very carefully looked after, you may see clear failure.



Paint Gauges

You need to use a high quality one and those tend to be very expensive.



It's a valuable tool for you to use as a "pre" and "post" measurement so that you can check how much you have removed. You need a highly accurate machine though with very high sensitivity. Otherwise, the little amount you are removing might be within the margin of error for the reading and not really tell you anything.



I've never used but I have seen a bodyshop use it. It's neat, but the information it gives you needs to be interpreted correctly. Too often, people don't understand that it's not the clearcoat thickness but a function of the primer, basecoat, candy (?), and clear all together!



However, how far you can go is really an experience thing and understanding what the actual thinkness of the clearcoat is.
 
I just checked out that Meguiar's thread. Pretty cool.



Note: After just 1 bit of wetsanding and polishing with Diamond Cut/DACP. He's removed what is the recommend 0.3mil maximum. Therefore, if someone in the future was to further polish with Diamond Cut or DACP and remove a further 0.1 or 0.2mils, it would be getting close to that threshold level that could compromise the clearcoats UV-protection.



So, the Moral of the story is. You're pretty safe using a SMR or DACP by DA a few times a year, However, any wetsanding or heavy polishing (even just once) and you need to very careful. The hardest part is if you have a used vehicle or you're a detailer and you don't know what has been done before. Going in blind could be very bad.
 
i dont understand that link. He did all that to the paint and brought it down .3. So that means if he repeats that process 1 more time, hes going pass the clear?
 
This depth assumes you bought your car new or had it repainted. If you bought used you really don't know how thin your clear is without gauges. Even some new cars have been repaired at the dealer due to transit damage that you may not be aware of. They are not required to tell you.



IMHO, way too much attention is being paid to using harsh abrasives every time a swirl is discovered. Many products that are available today contain oils and fillers that effectively make swirls disappear. Covered with a good polymer sealant and they will remain hidden for several weeks. I'd suggest that a major polishing should not be needed more than once a year. If you are getting swirls frequently it would be much better to find out what you're doing wrong in maintaining your finish.



Then again it's only paint and you can get a good show car repaint for under $5,000.
 
jfelbab said:
Then again it's only paint and you can get a good show car repaint for under $5,000.
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Just remember that it's only original once ;) and very few aftermarket paintjobs are as durable as the factory ones.



Also, it's sure hard to find good paintshops, and I've never had a decent job (glass out, trim off, plastic panels off, etc.) done for under $5K. But I guess everybody will have a different take on what "show qualiy" means. People ship rare cars from Europe to have them done at the shop I patronize, but I find their work ony so-so. I'll critique work on some priceless car and they'll say that "nobody else will ever see that". Must be true or they wouldn't get the business they do.
 
I think it is very difficult to polish so much that you remove clearcoat. It will take some aggressive procedure to do that. I'm sure if you do a heavy polishing more than twice a year, the probability of damage goes way up but is this really an issue for us?



I only use SSR2.5 on the Lexus once a year and with soft pads.
 
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