Wetsanding and buffing fresh paint

[gmblack3]

Top 10 thread for sure!

[JohnKleven]

David



I was reading your interaction with John Kleven, and he has very valid points.

So do you.



But here`s how I try to break things down, to be truthful and honest when giving advice.



If I have to beat YOU and JOHN in a three way sanding and buffing contest, with the goal primarily being a very leveled surface... how would I do it?

Bring it on Kevin



All very good points made. One trick that can help keep the finish flat with a d.a. is to make a full sweep sand from one end of a panel to the other, and not go back and forth. I see a lot of people sanding with D.A.`s sanding back and forth, which can create low spots at the end of each stroke, especially if an area is receiving constant attention, such as nibbing out dirts. Certainly starting with the most aggressive sandpaper will also create a flatter finish, as you don`t want to round the tops of the orange peel, they need to be sheared off. Kevin, your diagrams, and write ups are great!







John

[Kevin Brown]

Top 10 thread for sure!

It is a fun and informative thread.

[Kevin Brown]

Bring it on Kevin

Ah, no thanks... I`d probably get smoked.... you sound a little too confident.

Much rather work with a guy like you than against.

All very good points made. One trick that can help keep the finish flat with a d.a. is to make a full sweep sand from one end of a panel to the other, and not go back and forth. I see a lot of people sanding with D.A.`s sanding back and forth, which can create low spots at the end of each stroke, especially if an area is receiving constant attention, such as nibbing out dirts. Certainly starting with the most aggressive sandpaper will also create a flatter finish, as you don`t want to round the tops of the orange peel, they need to be sheared off. Kevin, your diagrams, and write ups are great!

John

All good info... potential for low spotting any time the machine tilts a bit, as it might when stopping to change direction.



Thanks for the compliments, too. :thx

[Kevin Brown]

Barry, your mind runs as fast as your fingers type.

Let me break this down in sections, and give my opinion that way.

Kevin,

So we talked about paint leveling on the bodyshop side of things, what if we look at paint leveling on the detailing side of things? Generally speaking Im not talking about a level surface as in orange peel removal, but as in complete scratch and defect removal.

I hope we can agree to reserve the term leveling for those instances when we want to minimize the peak and valley variances of a paint surface. This way, discussions about leveling or truing of the surface won`t get overly confusing for newbies.



At least for the remainder of this discussion:



To level a surface means to minimize the peak and valley variances of the surface.

Orange peel, waviness, and long, level sanding marks shall be categorized here.



To refine a surface means to minimize or eliminate unwanted elements from the surface other than those listed above.

Elements include scratches, pinhole-sized divets, or etching marks (isolated low spots).



These definitions are as distinct as I can think to make them right now.



I wish to make the distinction because we could feasibly refine or eliminate the imperfections from an orange peeled surface without eliminating its curvy peaks and valleys landscape.



In other words, if you said to me:



Barry: Kevin, see that sandy desert out yonder?



Kevin: Yes Barry.



Barry: If I asked you to level it with this flat shovel, how would you do it?



Kevin: I would take shovels full of sand from the flowing hills, and place them into the valleys until the surface was flat.



Barry: And if I asked you to refine the desert landscape, what would you do?



Kevin: Well Barry, I would take my flat shovel and pat the sand flat until it all of the sand grains were tightly packed together.



Barry: You`re hired! :dig

The old theory of compounding with a wool pad and then refining to remove the wool the coming back to remove holograms has obviously been changed with product development and game changing abrasives....



... Whats stopping us as detailers to look into finer papers likes 6000, 8000, 12000 grit, effectively allowing us to use a super fine polish to remove the sanding defects.

Nothing, except technology, and a company that sees the potential for financial gain in making a product for this specific purpose.



Suppose you made sheets and discs for us?

Better yet, what if you only made sanding squares, 1"x1"? :mmph:

Call `em Barry Squareys or something like that.



Hey, squares make it easier for me to explain this stuff. :typing:



What might occur as we use the squares?

What would be the factors that limit sanding performance?



I`m thinking this through as I type, so take it all with a grain of salt. :hairpull



No scientific data or research going on at my desk. :pray1:



These two factors pop into my head: Pressure points and void areas.



Pressure points.



Instead of grading Barry Squareys by grit size, you use a rating system that identifies your sheets by how many grains each one uses.



These are perfect grains by the way- all exactly the same and shape.

Pyramid shaped I suppose, with the base of the pyramid attached to the square.



Taking into account the machine`s weight and user applied pressure, your engineers determine that each sanding square can withstand 1 pound of downward pressure before the sheet crumbles.



In real-world sanding, too much pressure causes sanding particles to dislodge.

We don`t have a problem with sandpaper crumbling, thank goodness for that!



Therefore:

The 4-grain square would have .250 pounds of pressure atop each grain.

The 8-grain square would have .125 pounds of pressure atop each grain.

The 16-grain square would have .0625 pounds of pressure atop each grain.

The 32-grain square would have .03125 pounds of pressure atop each grain.

The 64-grain square would have .015625 pounds of pressure atop each grain.

The 128-grain square would have .0078125 pounds of pressure atop each grain.



This goes on and on to whatever degree you want it to.



But, there comes a point when there`s very little pressure placed upon each grain, so cutting power is virtually nil. In fact, each grain barely cuts into the paint.



Suppose you place the maximum amount of grains you can possibly fit onto your sheet, and the number is virtually uncountable. In fact, the surface is so tightly packed with abrasive pyramids, it feels as smooth as a piece of glass. You magnify the face of the sheet under a microscope, you realize that the sanding face of the sheet even looks as smooth as a piece of glass!





Void areas.



With so little space available between the grains:



Where is the abraded paint going to go?

If you happen to wet sand, where is the water going to go?



This could be a problem, eh?



If the residue immediately suffocates cutting power by coating the abrasive pyramids, your sanding squares would offer very short lived cutting power.



If the water had no channels to enter, the sanding square would simply hydroplane until the water was eventually pushed aside.



Would there be a suction problem, causing the square to stick to the surface like a suction cup?



Interesting. Perhaps not a great analogy, but I hope that it makes a little bit of sense. At some point, it seems to me that we`d have to use a mesh backing, or a pin-holed film backing, or some sort of material that would allow water and abraded paint residue to evacuate the area between the disc and the paint.



Vacuuming? A slurry and pump system? Perhaps.



In the case of sanding discs, maybe the abrasives could be lined up like straight spokes on a wheel?

Perhaps curved in a spiral fashion? Or just in straight and parallel lines? Hundreds or thousands of them?



I think someday we`ll see discs and buffing pads that work in a manner similar to stone polishing flexible diamond discs. Hard yet flexible pads impregnated with diamond grains, or some sort of abrasive. Envision the way paint cleansing clay works.



We`d use them along with a mist-on lube, or water.

Is it possible to hydroplane a film disc across the paint to create an almost final shine? Just something running threw my head as thoughts and playing around happens. could we see the day of polish liquids be virtually gone?

You`re wondering if we could somehow fill the low points of the paint with water or some other filler, so that only the high points remain, and the disc will only affect those points?



I think we discussed something similar to this a while back, in this thread:



Some Conversation Between Kevin Brown and Barry Theal



In that discussion, I mentioned this:



"In reference to water or lubricating agents in general:

Since liquids are not easily compressed (most times they are deemed to be not compressible for simplicity sake), the layer of liquid might cause the pad to "float" or ride atop the liquid to some degree. If the pad also features a layer of liquid spread across it, the net effect might be one that sees only minimal contact between the pad and paint surface. Consequently, only the highest of points of the paint surface are being affected, and the newly formed paint surface would lack sharp or inconsistently shaped features.



To envision this, imagine that you are going to skip a rock across a pond of water, and the water is at rest (so its surface is basically flat). The pool of water has small pieces of grass sticking through the top, and you want to cut a path through the grass so that it is flush with the water level. You sharpen the edge of the rock so it will cut through, and you make sure when you throw the rock, it has a lot of rotational speed.



This scenario is very similar to what is likely occurring during your "burnishing" step when you polish paint with a finishing polish. In this case, the pond water represents the liquid covering the paint, the grass blades represent the high points of paint that your pad is going to "cut through", and the rock represents your buffing pad. Not a perfect analogy, but I hope you get the gist of the comparison."



Oooo-kay!

A long day of product testing and a bleep load of typing... it`s now 2:42 a.m.

Time for quick five mile jog, change the oil in my truck, and off to bed. :spot

[David Fermani]

If leveling can be done without one, meaning that I don`t gouge the paint with the edge of the disc, I`ll do it.

My thoughts exactly.



It seems that almost always, I end up using an interface pad.

Me too for the initial leveling.



It`s just too darned hard to keep a machine totally level.

Yes. I`d rather do things on the safe side by using an interface (cutting less abrasively) and make a few extra passes where needed.



When I use Abralon, I rarely use an interface pad, unless the panel shape requires one. The nice part about that brand is the soft backing material that almost acts like an intereface itself.

Does that answer the question alright?

It sure does. Thanks for all your stellar insights.



One more question since we`re on the subject of interface pads. I`m under the impression that they can "water down" the sanding strength of the paper by as much as a 500 grit loss (or more). Do you know of one that is less parasitic or effective and still keeps the safety aspect intact?

[Kevin Brown]

One more question since we`re on the subject of interface pads. I`m under the impression that they can "water down" the sanding strength of the paper by as much as a 500 grit loss (or more). Do you know of one that is less parasitic or effective and still keeps the safety aspect intact?

A question that begs a discussion, rather than a specific recommendation.

That being said, take a look at these:



Mirka 9166

Mirka1066F



Now, off to the races! :madgrin:



There are two possibilities that I can think of right now that might cause this to occur.

So perhaps knowing the cause, we can minimize the occurrence.



First, the sanding disc`s backing material generally dictates how much the interface pad affects sanding efficiency in the way you mention.



To paint a visual of this, lets take it to extremes.



If we were using a sanding disc that featured a hard and non-flexible backing material such as cast iron, the backing would remain rigid, regardless the characteristics of the interface pad. So, the only affect the interface would have on sanding would be limited to how it affects the machine`s action.



If we were using a sanding disc that featured a soft and flexible backing material such as Saran Wrap, the backing would follow the oscillations and fluctuations of the interface pad`s attachment material.



If we were using an interface pad with either of the aforementioned discs, and the interface pad featured a hard and non-flexible material to which its Velcro hook material was attached, then the characteristics of the sanding disc`s backing material would be irrelevant.



Does this make sense so far? If not, perhaps read it once more before moving on.

It may make sense to me as I write it, but it may be perceived by you differently.



Not good if this is the case. :nervous2:



Okay, back to the real world of sanding discs and interface pads.



In our realm of sanding, a typical disc uses either a film or paper backing. These backings are rated using a letter system to identify the film`s rigidity. Discs with an A-weight backing are more pliable than those featuring a B-weight, and so on. Film and paper discs with E-weight ratings are pretty darned stiff; those with F-weight ratings can even be used as grinding discs! Cloth discs use a different lettering code (J, X , W, T, M)



This letter system is not used to identify the rigidity of other types of backing materials.

So, for products such as Mirka Abralon and Abranet Soft, and Meguiar`s Unigrit Foam Finishing Discs, we must rely upon manufacturer claims and our own experiences to better understand how these discs will react to the effects of an interface pad.



Lets compare a film backed disc to something like an the Abralon disc.



Abralon discs don`t typically need an interface pad, because there is a layer of foam built right onto the back of the disc. These discs contour exceptionally well because the backing material isn`t flat or continuous like a film disc, but instead is composed of a very pliable fabric:

If there happened to be a small protrusion of the sanding surface, the Abralon disc would be more apt to contour over it, rather than rifle straight through it. AND- when the disc did contour, the immediate areas around that point on the disc would be barely affected, so they would continue to level to the degree that they had before. A typical film disc would not be able to do that.



Now... if the foam material used on the Abralon disc is softer, more resilient, and more contourable than the foam and components used to make the interface pad, then disc`s foam will affect the sanding results immediately. So, let`s assume for the moment that this is the case, and our interface pad features a stiffer and thicker foam. For lack of a better term, it has a stiffer suspension system.



If there is enough applied pressure or enough of a surface variance present to "bottom out" or compress the foam mounted to the Abralon disc, then the interface pad`s characteristics will kick in.



If the opposite is true, that our interface pad`s suspension is softer and more pliable than the Abralon disc`s foam, then the face of the Abralon disc will remain relatively flat until ample pressure or variances of the sanding surface are large enough to affect it.



In the end, an interface pad can affect sanding aggressiveness, but usually does so in a manner different than some might think.



Wouldn`t it be cool to have a disc that allowed us to individually place our abrasive particles into a hard, pin-holed backing?



Each abrasive grain would be attached to a pin head, and you could stick the pin in the pin-holed backing.



I`d get a few thousand of the pins with the built-in adjustable coil springs, so I could dial in the "interface affect" I`d need for the job. Or, for flat sanding, I`d just use the non-springed pins.



Hey, we already have Barry Squareysâ„¢... How about the Davidiscâ„¢ Sanding System?

Put me down for some 3" and 6" backings, and 10,000 pins with the infamous Davidiscâ„¢ Diamond Tips!



If you want more info, I have a page on my site about interface pads: More About Interface Pads

[Kevin Brown]

Another day, another sanding session session!



Just started on sanding a Chevelle today, and teaching my detailer friend Tim how to sand for the first time. So far, so good. I set him up with a test panel and let him sand with Unigrit Finishing Sheets, 1000 grade. Then he re-sanded with a 2500 grade sheet, but in at 90 degree direction to the 1000 grade.



This way, he could see if he removed the 1000 grit marks completely. Had him buff it out via rotary, Meg`s burgundy cutting pad, and M105 with mists of water. He`s buffed before, so not a big deal for him there.



Once the panel was all dialed in, he stripped it with glass cleaner, and re-sanded again, but this time with sanding discs via the G110v2 random orbital, speed 2 or so. Just enough speed to keep the backing plate rotating once every 4 or 5 seconds.



First he sanded with Abranet Soft 1500 grade discs, then used 2500 grade .

He was blown away at how much better and faster the sanding looked- consistently dull across the panel. Well, he learned that just because something sands out well doesn`t mean it buffs out well! Hello piggy piggy... yup, the dreaded pigtails.



I explained that he needed to watch that he didn`t tilt the machine as a beginner, and to move slower, and to keep the disc clean. Much better the next time around. We also discussed how discs and sheets work differently- pretty much stuff that was covered in this thread, but not to the same extent by any means.



I`ve got him sanding the roof of the car, nice and slow, watching his speed and stroke length. He`s starting to catch his own mistakes, so he`s a fast learner. I followed up his sanding with a couple passes using Abranet Soft, 1000 grade, then refined with a 1500 grade Meguiar`s Foam Finishing Disc, and then again with the 3000 grade, which in simply a fantastic disc- probably the best finishing disc available today. All with a Mirka Bulldog 3/16" stroke sander.



Back at it tomorrow. I`ll try to get some pics, but it`s a white car, not great light. So far, not great shots. At least I can get some reflection shots of the fluorescents and the sky lights... see if they look less wavy and crisper. It`s not a show car or a super high end paint job, but it was sprayed well, and should look pretty clean.



The goal of the job:

1. Don`t burn or ruin the paint!

2. Keep the long term integrity of the paint intact- leave as much paint on the car as possible.

3. Make it smooth, mar-free, and glossy.

4. Teach Tim the basics of sanding.

5. Make a few bucks for Tim and me!

[RaskyR1]

In for the pics! :showpics:showpics



What year Chevelle?

[Kevin Brown]

Supplies:















My friend and fellow detailer, Tim:







Proper hand placement makes a difference:







World`s skinniest drum buffer:







Pull in some M105 and water as needed, all with a light touch @ 1500 RPM:

[C. Charles Hahn]

Is that one of the Solo wool pads, Kevin?

[Kevin Brown]

Is that one of the Solo wool pads, Kevin?

Yes.

I brought along two burgundy, two yellow, and some 3" and 3-1/2" wool pads for my little Mirka MR-30 rotary polishers.

[JohnKleven]

Yes.

I brought along two burgundy, two yellow, and some 3" and 3-1/2" wool pads for my little Mirka MR-30 rotary polishers.

What`s with the buffing on edge? I was trying to figure out what he`s doing?

[C. Charles Hahn]

Yes.

I brought along two burgundy, two yellow, and some 3" and 3-1/2" wool pads for my little Mirka MR-30 rotary polishers.

Nice. I just picked up a couple of those the other day, looking forward to trying them out! I really like the 3" wool spot buffs that Meguiar`s has for spot work on my Flex 3403 as well.

What`s with the buffing on edge? I was trying to figure out what he`s doing?

Looks like he`s buffing down into the drip rail over the doors/windows, while pulling the bead of product and lubrication in as he goes. The edge of the pad is just about the only thing that will get down into that tight space.

[JohnKleven]

Looks like he`s buffing down into the drip rail over the doors/windows, while pulling the bead of product and lubrication in as he goes. The edge of the pad is just about the only thing that will get down into that tight space.

Yeah, that`s what I thought too until I saw the last picture.