ETG Testing Results of Compounding

I always look forward to your posts RAG, they are quality..but this test is just awesome! Such great info for those of us who were a little fuzzy on how much clear there was and how much we're removing with various buffing jobs. I know they're just a baseline but just having a ballpark is great, and comforting. If I had a ptg I'd take some measurements. I'm sorry if I missed it but what PTG are you using?
 
Great post RAG! Thanks for taking the time to do this :up



I'm willing to do some more testing, I just need you to send me the ETG :D
 
DSVWGLI said:
What did this reveal in microns removed? How much was removed with sanding alone, and how much all together?
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I didn't measure before sanding, so I don't really know. Basically, what I did with the sand paper was last minute...I buffed with the black Edge wool and HETC/OC once, then decided to sand a small area within my buffing region to see if the 2000 grit marks would come out with one polish (4 passes), but it didn't...I had to polish again before the marks were removed.
 
Lightman said:
I always look forward to your posts RAG, they are quality..but this test is just awesome! Such great info for those of us who were a little fuzzy on how much clear there was and how much we're removing with various buffing jobs. I know they're just a baseline but just having a ballpark is great, and comforting. If I had a ptg I'd take some measurements. I'm sorry if I missed it but what PTG are you using?
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It's the Phase II seen here: Car Detailing Store, auto detail products and car detailing supplies and equipment



And I'm glad you found the results useful...they were a bit hodge podge, but oh well.
 
Also, something I wanted to mention (and I'll do further testing to confirm) was that I used equal pressure with all of the pads and products, but one of the advantages to a cutting pad is that you can apply a lot more pressure...so I'm betting that in order for a cutting pad to provide a lot more cut, you have to apply a lot more pressure (of course this will leave the surface a little more tore up too). And this applies to wool too...when I'm doing heavy scratch removal using a lambwool pad, I can usually remove 5-7 microns of paint by polishing just once by focusing on a small area and using a ton of pressure.
 
RAG- A belated "thanks" from me too for running this test, makes me want to get a ETG too.. gotta find an affordable one that'll work on the aluminum cars.



I too was surprised that you didn't take off more than you did with some of those combos! Gotta get myself some wool pads.



Here's a seemingly different experience, noting that I don't have an ETC and I'm judging what's going on by eye:



I'm working on the '97 M3, never aggressively polished before that I can tell, lots of previous-owner abuse, and I plan on eventually getting it repainted (regulars here know how much I despise repaints if they're avoidable). I'm using the rotary/orange or yellow cutting pads/H-T EC, working each area until the scratch-type marring is gone (got pits, and solvent-pop on repainted panels, that I'm leaving alone).



Remember the clay you sent me? The marring from that comes out easily with the first light pass, but the scratches require numerous additional passes and some of those are with pressure. By the time I get the serious marring out I'm left with areas where the clear is *visibly* too thin; with very careful inspection I can see that those areas have less depth/richness, the color appears lighter and the metallic effect is more pronounced. In other words, if I weren't resigned to a repaint I would have to quit long before I get the scratches out even though they don't look all *that* bad. I only mention this as an "every case is different, be careful" type of FYI to those who might be considering some aggressive action of their own- get an ETG, you simply can't make assumptions about this stuff.
 
RAG said:
..The one I have works on Aluminum...
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Ah, OK, my bad for not checking out the specs on the link you posted. I really oughta get one of those lest I repeat the M3's over-polishing on something else (like something I'd hate to mess up).
 
Gosh, I have yet to come across an over polished vehicle (except where I tried to get a nasty key scratch out of my mom's lexus).
 
RAG- Seems like I've had a *lot* of over-polished cars, some of which I really cared about. Perhaps this is why I keep advising people to err on the side of caution and live with some marring. I've read all the posts (here and elsewhere) about how not much paint gets taken off, but having seen it first-hand (and seen it cut to basecoat and even primer), I'm in the better-safe-than-sorry camp. A few more examples:



Another one that was visibly over-polished was my latest Caprice copcar (which I *think* I just sold this week). The previous owner did a nice job of wetsanding and rotary-ing the (beat) factory paint but IMO he went too far- same story as with the M3, there were a lot of areas where the color appeared lighter and more metallic than it should have. It looked incredible for a 110K copcar, but if you knew what to look for (and cared), well, I sure wasn't gonna leave it out in the sun for very long ;)



Another one was the old Volvo wagon I inherited. My fault...I took the *incredibly* abused factory single stage (never waxed for over a decade, outside 24/7, washed in winter by "rubbing it with snow and brushing it off") down to primer in a few spots and not just on crown lines and corners. Did it with a PC/Cyclo too, *not* a rotary. Heh heh, I took it down to primer in a few more places once I took the Makita to it :o but by that time I'd scheduled a paintjob anyhow.



The paint on the Jag is too thin to truly correct the marring too, I took off too much with a Cyclo over the course of 20-some years. The guy who's doing the spot-in paintwork has cautioned me that it's gonna look awfully blotchy if I polish it any more..bad news for single stage lacquer, which is gonna oxidize and need polishing no matter what I do to preserve it.



That's a lot of overpolished cars for one guy to think of right off-hand, see why I'm sorta paranoid about it?
 
Thanks again RAG for sharing some great info. I always enjoy this topic and think it’s important, especially if someone is working on older vehicles.



I found the ETG to come in very handy on older muscle cars with single stage paint jobs. You never know what you're dealing with on these older cars because some have been repainted many times, some have had plenty of body work, some have wildly inconsistent paint thicknesses, etc. Sometimes the paint is so thick from repaints that it's starting to crack and or peel in certain areas (typically on cowling or curved surfaces) and sometimes polishing these areas can makes things much worse. On numerous occasions I've seen older muscle cars where the flat surfaces had incredibly thick paint (12+ mills), BUT...some of the sharper edges were whisper thin from years of polishing and or from the painter (poor technique, and or process, and or materials, and or environment, etc). Sometimes a light compounding by hand is enough to remove the remaining paint in some areas and this could be devastating to the vehicle owner. The ETG allows me to better inform the vehicle owner of what to expect and it also helps me to determine the process + products I’ll use for specific areas.



Sometimes a horrifying looking single stage paint job can be made to look incredible with enough work. But to be safe in these cases, a person needs to know where they can safely use aggressive products + processes and where they can’t. The ETG has greatly reduced my risk in these situations and I wouldn't be without one. However, the ETG is ‘not’ the perfect tool. It only provides a measurement for the total film thickness (primer + paint + clear). But, if a person combines some knowledge, some common sense and experience while using this tool, it will definitely reduce a person’s risk.
 
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