Wetsanding vs. Rotary vs. PC, what removes more paint? (The answer may shock you)

[wannafbody]

Hmmm....



Ok, so your RO was sanding and your rotary was cutting.......(basically from your post)



Did the sanding action remove more cc than the cutting action....? (pads were different, so it`s hard to tell here IMO)



Two steps are nice but, is it possible that the first rotary step removed more scratches from the surface than the RO did....?



Heavy compounds with a rotary can do some serious paint damage in a hurry if your not careful. Heavy compounds with a RO will not do as much damage as quickly using the exact same products .....IMO

It also has to do with the hardness of the abrasives. Aluminum Oxide is very hard and takes more friction to break down.

[imported_DieselMDX]

this is going to get good. I can already tell i am going to learn ALOT from this thread

[salty]

Great write up Todd.

[Carbon Blue]

I have to agree with Todd on the D/A vs. Rotary in chasing. Since the rotary works much faster than a D/A at correction, you are able to flatten the surface in a shorter amount of time, thus preventing the pad from dipping down into the crevice (persay) of the scratch and thus "chasing" the scratch further and further into the surface. Its crude logic, but it does make sense. (to me at least.) I dunno, maybe im wrong.

but why wouldnt the rotary chase the scratch?

[admac]

very interesting results and it does follow logically. whenever you have a decent scratch on a car and you polish it with a da or forced rotation machine you see that the scratch gets less noticeable but that the "walls" of the scratch spread a bit too as you work it. so where before it was a sharp thin line, it starts to become a less defined wider line.



if the line gets wider, it makes sense that you`re removing some material from the valley of the scratch as well. and if you`re using a pc you`re going slow enough that you could really work that low part. a rotary probably spins fast enough that it`s more likely to shave the top off rather than work the whole thing down.

[imported_rydawg]

Great write up Todd!



If ya need any explanatory or help, just let me know.

[imported_Denzil]

Pretty interesting theory... it sounds pretty logical to me.

[Can You Hear Me]

GREAT write up. Made me think completely different about how precise wet sanding is.. So should I be less or just as worried about wet sanding an entire panel of my car (say a door) with 3000 making only 5-8 light passes on the whole door to remove OP/Scratches/Swirls/Rids ect. Then polishing out the sanding marks. Should I be worried about this taking away too much clear and removing the UV protection in the CC that the factory left behind? I am eager to wet sand some spots on my e30 that have more OP than others but did not want to remove too much CC and cause failure later down the road. I have all sand paper in my aresenal from 1500 to 4000. I would be doing this by hand and using optimum polishes/compounds and a purple LCC wool pad to remove the sanding marks.

Thanks.

TH- You REALLY know your stuff. I apriciate you always posting in depth well educated responses to everything on this forum. It has really help save my detailing process so much!

-Nick

[imported_DieselMDX]

GREAT write up. Made me think completely different about how precise wet sanding is.. So should I be less or just as worried about wet sanding an entire panel of my car (say a door) with 3000 making only 5-8 light passes on the whole door to remove OP/Scratches/Swirls/Rids ect. Then polishing out the sanding marks. Should I be worried about this taking away too much clear and removing the UV protection in the CC that the factory left behind? I am eager to wet sand some spots on my e30 that have more OP than others but did not want to remove too much CC and cause failure later down the road. I have all sand paper in my aresenal from 1500 to 4000. I would be doing this by hand and using optimum polishes/compounds and a purple LCC wool pad to remove the sanding marks.

Thanks.

TH- You REALLY know your stuff. I apriciate you always posting in depth well educated responses to everything on this forum. It has really help save my detailing process so much!

-Nick

great question i am interested in this also

[Neofate]

Good stuff. This also brings new light to wetsanding and the differences in Rotary vs PC. Which are often ambiguous at best.



I understand your theory, and ultimately I think it was said best that settling for a little less than perfection is the best option. 96% is good enough if it saves alot of the paint. imho.



But, its good to chase a hypothesis..



So wetsanding with 3-4k paper is really, ultimately, safer and removing less than a Rotary or RO with an agressive compound? My question is how much pressure is (average, or appropriate) when wetsanding with this method.



I think it makes a valid point that with a RO you are at the mercy of the speed of the polish breakdown. At any point during that breakdown the correction can and is being made. At points after the made correction you are removing unnecessary paint. RO is not an exact science, not by a longshot. But it is safe enough that you remove a little excess to achieve perfection without the dangers of cutting too much.



The rotary does this much faster, and you can back off a little sooner and wipe to check.



Technically you can back off the RO and wipe before it has completely broken down, but if it isn`t to your liking, you have to reapply new and break down completely again. Removing more than you previously would have.

[Todd@RUPES]

but why wouldnt the rotary chase the scratch?

I would think that a rotary does chase down the marring/scratches as well. But one of the advantages is the abililty to uses a more aggresive approach which should remove everything around the scratch quicker. I guess its hard to explain, but in my head (which means nothing) I would think the rotary would do less chasing because of the speed at which it removes paint.

[imported_agentf1]

Nice write up and makes perfect sense. Next time I would love to see how these new Forced Rotation ROB buffers like the Flex or Makita BO6040 fair as far as paint removal.

[Macruz19]

Come on down to Orlando and I`ll show you how to do both.



I will also do what I did with Pats300ZX (the moderator) and prove to you that SIP and 106ff fill (ask Pat).

I come down to orlando a few times a year. I might contact you sometime. :usa

[AP2TUDE]

I think that this also needs to be contrasted with wet sanding by machine.



This thread on DetailingWorld was really really informative on the true value of consistent wetsanding.



The findings in this thread really enlightened me. They showed that the machine wetsanding was much more precise at removing specific amounts of clear than simply compounding them out. Logically this makes a lot of sense. Sandpaper doesn`t break down like polishes do, which means that across the surface they are very consistent. Polishes can break down unevenly across your work surface, meaning not only will scratches break down unevenly across that surface, but your overall clear coat level will remain uneven.



They also showed that since the sandpaper breaks down the clear very quickly, you can use multiple sanding steps up to 3-4000 grit and then a minimal amount of finish polishing in order to achieve a perfect finish. They showed that using their techniques, a vehicle in need of serious correction could be finished much more quickly, and effectively, by wet sanding and polishing than by polishing alone.



Couple that with these findings by Todd, and it makes sense that it would not only be a faster way to finish a car, but more clear coat conscious as well.

[imported_Detailing Technology]

You also knock people out with the finished product. Road "dimples" are dramatically reduced. Scuff, abrasions, rub-off is removed or seriously lightened. The surface if the car is completely stripped and renewed, most of the time flatter then when you started.



My opinion is this demonstrator goes too close to the edges. In wet sanding over 1,500 cars, I never would go right to the edge of a panel like that. I always leave 1/4" untouched. Edges are where you burn paint 99.999% of the time. Why risk it, you will never notice the difference.



The trick is finding enough customers to pay for it. I wouldnt go through the steps without adequate compensation.