Wheel well and leather dressing

J

janderson

New member
Sadly, I came out to my car tonight, and it was covered in a fine powder of dust. I will not be able to wash the car until Sunday (after Church), so what should I do?



I think that I am going to take it to the Mobil (touchless wash), and get it rinsed there. I need to get the grime off of the car, or I fear that it will stay on the paint too long.



What would be the best recommended plan for this type of situation? Also, I am concerned when I am using my MF wash mit I am possibly putting more scratches in the paint. I use two buckets when washing (one with shampoo, and the other with clean water), but when there is a film of dirt on the car, my concern is that it acts like sand paper on the paint. What are your thoughts on this matter?



Best regards.
 
Do you think when you rinse the car prior to washing it would get most of this dust off?



If not maybe a visit to the pressure washer first.:nixweiss
 
I'd just take it to one of those coin operated self serve car washes and spray it all away..but if it sprays away easily will depends on what kind of powder it is and how much there is..
 
I own a pressure washer, and my washing routine normally consists of a pre-wash using the high pressure. Don't get me wrong, I don't go nuts or get close, I just wash the truck down, and normally remove 50 - 80% of the surface dirt. That leaves the thin layer or film that is bonded, and must be removed by washing with a mitt. After I complete the wash, I rinse with the pressure washer again to get an effect similar to the no nozzle trick. I like the pressure washer better, because I can actually push the water off the surface by sweeping the wand.



I used to do the same thing at the coin-op, until I decided I had bought about 3 pressure washers already, so why not buy my own.
 
Maryland - dust won't hurt the car to stay on it - as long as it is dry. There is increased risk of getting swirls if something comes into contact with the paint and drags the dust around, but the dust shouldn't be very reactive with your paint in its dry state.

When a dust layer is really thin you can remove it with a "california car duster" or detail spray and a microfiber wipe. The more dust, the more chance there is of some scratching while doing this.

I'm actually inclined to recommend AGAINST spraying-only. Here is my thinking. If you've ever washed a car without actually wiping the surface with a hand, a towel, a mit - even if you spray soapy water - you know that there will still be a very fine film of dirt left on the car afterwards. You can get a great deal of this off with a pressure washer and a LOT of time spend on each panel - but whatever remains is now WET. And THAT stuff is gonna be MORE reactive with our paint (although this isn't a big cause of paint problems that I know of), and it will be more stuck than it was before, requiring a "real" wash. So - why not just wash it that way in the first place?

For the scientific explanation of why you can't spray all the dirt off: There is a phenomenon called the "boundary layer" whenever a fluid (air or water) moves over a surface. The fluid high enough up to completely miss the surface is out of the boundary layer and is moving at full speed. The stuff that is extgremely close to the surface <strong class='bbc'>doesn't move at all[/b]. (Hence - the smaller particles of dirt don't get moved.) Aerodynamicists study this layer in detail for airplanes moving through air; hydrodynamic experts study it in detail for submarine design.
 
the no slip boundary condition. It is mainly used to study flow through pipes, and air over wings to get a flow profile. The wetting of the dust could be enough to lift it off the car to be washed away, but I have found that unless you agitate it with a washmitt and car wash, it is a risk you take of not moving it completely. If you just rinse....do not dry the car...just drive it at 80 mph to dry till the next wash and it should reduce the amount of dust on the car to satisfy you. As carguy said though, the dust will not hurt anything for a few days. If you could live with it, just deal, and wash it over the weekend........
 
All you really need to do is bring it to the car wash, stand back a good three feet from the car and spray the car with the "rinse cycle".



I like to clean the rims while I am there...
 
If you re-read my post, you'll see that I do wash with a mitt. I also use Z-7. The pressure washer is used only to pre-clean the surface and wash away the majority of dirt on the surface. This greatly reduces the amount of dirt I have to remove when using the Mitt and soap. The goal is to reduce the possibility of scratching or swirls when using a mitt. We all know that sometimes our cars get very dirty. Especially after a winter storm. I just cannot bear the thought of washing the car with a mitt and hose only in those conditions even with the best mitt on the market. The pressure washer allows me a margin of safety.



Also, I don't blast away and spend a lot of time on each panel. The surface dirt thats going to come off, will with a quick pass. I also don't use car wash detergents that are approved for pressure washer use (even with the downstream injector), because they are much to harsh.



Hope this cleans things up! ;)
 
laynlow - I didn't mean to imply I was responding to your post. I was responding to MarylandBimmer's original one. Since the subject of spraying/rinsing came off I just wanted to clarify that alone it isn't enough. Sorry for the misunderstanding.
 
Oh, I gotcha. Makes sense now. I wasn't upset or anything, I just didn't want a fellow autopian thinking I just rinsed and dried!! Ouch!
 
I find that with sufficient coats of KSG, the slickness of the surface allows a gentle swipe with a california duster to easily remove fine dust. Of course this can only be done within a week or so of washing the car, after that the grime becomes too hard to wipe off and I'm afraid of scratches.



I do have a white car, which hides scratches, though.



Once the car gets rained on, I'm not sure I would use the duster, though, unless the surface was particularly smooth.
 
I didn't really get all the details of what this is from the 2 brief posts above but this morning my Calculus professor just happened to start talking about something that sounded like this. Let me know if my interpretation / understanding of his brief explanation is correct.





Consider a downhill slope, be it on your car or wherever (are there any long enough on a car?). When a continuous flow of water starts going over the surface, it flows downhill normally. But then it starts accelerating and moving faster. The friction (?) between the advancing water and the surface causes the water at the back to actually start pushing on the water at the bottom of the slope.



The problem is, water is not compressible. When the top water pushes down on the water at the bottom, it meets with resistance. The back water then actually "jumps up" and goes on top of the front water!





Am I right? What happens then? Does the "back water" which "jumps up" (technical terms please? fluid jump?) to the top actually go all the way to the front and drop back down? If so, would this be a continuous wave action that keeps circulating water from the bottom to the top?



:nixweiss
 
Ah PUTEY let me see if I can help confuse you some more.



When a fluid is moving ... lets use air for this .... across a surface the air closest to the surface is going slower than the air above the surface. This is due to the effect of friction and other forces between the surface and the moving air.



In theory the air is actually static against the surface.



...but what carguy was saying is that when air blows on your car while driving the air in contact with your car is moving slower than the air slightly above so it does not blow off all the dust.



so this air at paint level does not have enough force to actually blow off all the dust. The dusts attraction to the paint may it be from static electricity, adhesion (stickiness), gravity, and those other forces you learn about in physics can be pretty strong.



Did I confuse you more?



Well since water has more mass than air it will do a better job of removing this dust.



And the water in your example flows over the slower water and becomes deeper until gravity brings it down like a wave. But waves behave like they do at the beach due to the up slope of the ground.



Confused yet???? LOL
 
Actually SL this is in fluid mechanics......very boring stuff!!!!



Calculus just lets them make these horific equations to explain it more confusingly. LOL
 
Is what is formed. The no slip condition is met at the surface and the profile moves outward from there. The farthest away from the surface is where the flow is the greatest, hence the largest dirt particles are swept away easily and the smallest ones are left on the car. Same thing happens when using air to clean off sunglasses lenses....the smallest particles are in the lowest flow of air stream and remain behind.........neat huh?
 
Gotcha! That sounds rather interesting, I will probably enjoy learning about physics when I get to it . . . except for the calculus "part." Notice I use the term part <strong class='bbc'>very[/b] loosely here.
 
I always rinse (no blasting) and drive (no wiping!). Besides your other choices are CA duster and QD with MF. In the mornings it's about the easiest and quickest way to get a layer of dust off. Should any does dissolve and "react" with you paint you must rinse a lot so that there is enough water to dilute any local reactions if acid is your concern. Remember though, Newbury is a little piece of pollution free place on earth! ;)



We can all hope that the extremely close particals that don't move or don't get dissolved are also less easy to see. The result is a "cleaner looking" car, until you can really wash it on the weekend.
 
...I thought it would never come to this, but you guys started it... ;)

I deal with boundary layers every day (I'm an aerospace engineer and my master's specialty was in computational fluid dynamics). You guys have a pretty darned good grasp of the basics of BL theory. I'm not 100% sure that the reason that dust isn't removed from a car by wind or water alone is <em class='bbc'>entirely[/i] due to the no-slip condition (since the fluid velocity is zero only <strong class='bbc'>immediately[/b] adjacent to the surface of the car), but I'm sure that no-slip has a great deal to do with that pesky dust not wanting to blow off.

Anyway, for any budding fluid dynamicists or aero engineers, here's a pretty good layman's explanation of boundary layers. Enjoy!

:bounce
 
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