Wetsanding BLIND.....

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pingable

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Not sure where to put this question. Bodyshop seems a bit more logical....

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There is a difference to wetsand on fresh paint over *oem* paint.

For a pro to wetsand *blind* - no meter, not on a spot correction, but entire panels, what camp do you sit in. Is it OKAY to wetsand *blind* not knowing what you're working with or not...
 
I would only wet-sand freshly painted or custom paint cars and strongly advise against wet-sanding OEM paint finishes as the paint is usually very thin, or wet-sanding any paint without first using a paint thickness gauge (PTG) to check the thickness of available clear coat; consider < 110µ ( microns) the very minimum



Before you wet-sand and polish any OEM finish, you should know this will void the paint warranty and if you remove more than 0.3Mil (7.5 µ (micron) this will negatively impact the paint systems ultra violet protection.



TOGWT® Autopia Detailing Wiki – http://www.autopia.org/forum/car-detailing/136818-clear-coat-uv-protection-removal.html#
 
I have very little reservation about sanding OE finishes blind with something mild like 4-5000 grit since it is milder than some heavy compounds, but getting more aggressive than that, no way. I don't even like sanding refinish clear (blind) unless I know the painter and how much material they sprayed.
 
C. Charles Hahn said:
I have very little reservation about sanding OE finishes blind with something mild like 4-5000 grit since it is milder than some heavy compounds, but getting more aggressive than that, no way. I don't even like sanding refinish clear unless I know the painter and how much material they sprayed.
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Agreed.



Even with a PTG you are still sanding blind as you only know the total thickness and not just the CC thickness....unless you have an $$$$ ultrasonic gauge capable of reading individual layers.



I have sanded several repainted cars without knowing who did the work and how much paint was really there. All I had to go on was the owners word that there was plenty of clear and I made them very well aware of the risks before I accepted the job.
 
As long as I'm leaving orange peel behind I'm not worried, gauge or not. I'm very sure I can cut and polish a paint job without burning, but I'm not sure I'm not setting a trap for the detailers who may have to follow my work.



With all colorsanding, I have a standard disclaimer: I didn't paint the car, my warranty and liability extends only to the price of the work - anything goes bad, no charge, but that's it. Period. I don't know if that would hold up in court, but I've never had to test it.



In my experience, wetsanding with less than 2000 and a pretty hard block doesn't change the orange peel much at all - sort of like trying to block out a panel with 1200 - the paper mimics the peel, great for matching existing peel but not for eliminating it. That said, I wouldn't do a colorsand to eliminate the orange peel on OEM because OEM paint - IMO - isn't thick enough to take a first hit of 1000 or better on the first cut.



Just my experience, your results will vary.



Robert
 
Thanks all for the contributions.

Seems to be both sides of the coin. Half that won't without some level of reference, and the latter that will do it with either a disclaimer....or the word of the customer to do it cause the topcoat is thick enough to handle it.



Seems like alot is at stake without having a reading IMO. When topcoat starts to fail, and you get blasted on the forums....hard to state, well I warned X customer, but he told me to get rid of the orangepeel....you know how quick things spread like wildfire on the forums.



I've seen posts where a Pro uses wetsanding as both a tool and I suppose good *online marketing material*. To me, it's the opposite.......why would you be wetsanding a whole panel, hood, etc when you don't know how much you're playing with.
 
Chefwong this is a great discussion as I wetsand blind alot. Its a second nature for me. Just how I was taught I guess.Personally I feel paint meters have there place but i thjnk there more of a marketing tool for a dog and pony show to make a customer feel safe. If your taught properly how to read high and low spots in paint properly you shouldnt have issues. I know a few accomplished and respected detailers who dont use them.. Dont ask me to name names. Wetsanding is a real craft accomplished by a tradesmen. I look at it as the pinnacle acheivment in our field. So I sit in that camp. I prefer to trust my gut versus a computerized gauge. I think this is going to turn into a great debated thread. Thanks for posting this. Id be happy to answer any of your questions you have. Lets talk
 
Barry Theal said:
Chefwong this is a great discussion as I wetsand blind alot. Its a second nature for me. Just how I was taught I guess.Personally I feel paint meters have there place but i thjnk there more of a marketing tool for a dog and pony show to make a customer feel safe. If your taught properly how to read high and low spots in paint properly you shouldnt have issues. I know a few accomplished and respected detailers who dont use them.. Dont ask me to name names. Wetsanding is a real craft accomplished by a tradesmen. I look at it as the pinnacle acheivment in our field. So I sit in that camp. I prefer to trust my gut versus a computerized gauge. I think this is going to turn into a great debated thread. Thanks for posting this. Id be happy to answer any of your questions you have. Lets talk
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I can understand your position as thats how you were taught, but don't you think that given how thin some of the newer clears are getting, using a PTG is a good idea? I worked on a brand new M5 last week with readings from the 120s to low 80s. Doing any sanding with anything more aggressive than 2000 grit could leave next to nothing for clear in the thinner areas. Thoughts?
 
Barry Theal said:
Chefwong this is a great discussion as I wetsand blind alot...
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Heh heh, I was hoping you'd show up on this thread! I almost posted something like "where's Theal...isn't he back from Florida yet?" :chuckle:



One of the first :argue Barry and I ever had was about this very topic :fencing:
 
Barry Theal said:
Chefwong this is a great discussion as I wetsand blind alot. Its a second nature for me. Just how I was taught I guess.Personally I feel paint meters have there place but i thjnk there more of a marketing tool for a dog and pony show to make a customer feel safe. If your taught properly how to read high and low spots in paint properly you shouldnt have issues. I know a few accomplished and respected detailers who dont use them.. Dont ask me to name names. Wetsanding is a real craft accomplished by a tradesmen. I look at it as the pinnacle acheivment in our field. So I sit in that camp. I prefer to trust my gut versus a computerized gauge. I think this is going to turn into a great debated thread. Thanks for posting this. Id be happy to answer any of your questions you have. Lets talk
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I am in this camp with Barry.



I never use a meter but rather just go by experience and gut. I rarely sand with anything under 3k on OEM paint and ALWAYS give the client a disclaimer that there is a possibility that the clear could be broken thru. If they want the work done then at least they know the risks. If it's something we paint or a shop I know paints it we always request extra clear to work with.



This is why pro detailers need to develop professional partnerships with jobbers.



Anthony
 
I was brought in from the same camp as Barry. They can be a great tool but some times they are not useful.



Oops I just named a name.
 
I wetsanded my entire Infiniti FX35 OB, when I first got it. No guage. 1500 grit, thing was a mirror when I finished. I sold it a year later, no issues.
 
detailfanatic said:
When would they not be, John?
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There's always a limit to how useful they are; as it was pointed out earlier other than high-dollar ultrasonic units can only tell you the total thickness of the film. They are most useful for locating inconsistencies (signs that previous work has been done on a panel, telling you that the clear is already thinned out to some degree) and monitoring how much material you're removing as you work.
 
solekeeper said:
I wetsanded my entire Infiniti FX35 OB, when I first got it. No guage. 1500 grit, thing was a mirror when I finished. I sold it a year later, no issues.
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Given that every G35 that has run through my shop has never had readings as low as 58-60, I'd say you got pretty lucky.



C. Charles Hahn said:
They are most useful for locating inconsistencies (signs that previous work has been done on a panel, telling you that the clear is already thinned out to some degree)
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Thanks for the response. Wouldn't you agree that having this info would be beneficial before sanding?
 
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