Swirl question

[CharlesW]

Mike Phillips posted this picture in another thread.
My question is why does the marring show up in such a uniform circular manner. Chances are, very little of the damage was instilled in a circular manner at all, let alone in such a uniform pattern.

[akimel]

Re: Swirl question

My understanding is that the circular swirls are an optical illusion. In fact, the scratches are all over the place in all directions, but when viewed under a single point light source, e.g., the sun or a spotlight, they appear circular. Somebody with a scientific background will have to explain how this happens, though.

[Mike Phillips]

Re: Swirl question

Uniform swirls tend to come from a repeated procedure done to the car in a uniform way.

For example, if you always wash your car the same way and what' you're using to wash the car and your methods are not very good, then you will uniformly instill swirls over each square inch of the paint because you're rubbing the mitt over each square inch of the paint the same way and usually over and over and over again.

[Mike Phillips]

Re: Swirl question

My understanding is that the circular swirls are an optical illusion. In fact, the scratches are all over the place in all directions, but the light source causes them to look circular. Somebody with a scientific background will have to explain how this happens, though.

Explained this here in Hot Topics (where else?)

We often times explain this in our Car Care 101 class also because the question comes up once in a while...


Cobweb Swirls vs Rotary Buffer Swirls


Below is an explanation between the difference between random swirls and scratches that show up in what is commonly referred to as Cobweb Swirls as compared to Rotary Buffer Swirls.


Cobweb Scratches or Cobweb Swirls
Actually, the term cobweb swirls or spiderweb swirls comes from the fact that when you look at the paint in such a way as to place the reflection of the sun or another source of bright light so that it's on a painted panel, you'll see what looks like swirls and scratches forming in a circular pattern around the point of light.

Cobweb Scratches or Cobweb Swirls




Cobweb Scratches or Cobweb Swirls



Now if you move around a little bit so as to move the point of light around on the panel you'll see what looks as though the cobweb swirls are following the point of light. The cobweb swirls are not actually following the point of light what's really happening is that the entire finish is so filled with random scratches that wherever you place the point of light you'll see the circular or cobweb pattern show up because the random scratches will reflect the light back towards the center of this point of light. So as you move the point of light around on a painted panel it looks as though the cobweb swirls are following the point of light.

Does that make sense?

The scratches are not specifically circle scratches, they could be a all straight-line scratches but the effect is they look circular because the point of light is circular and the light hitting the hundreds of thousands of scratches are all reflecting back to the center of the point of light making it look as though the scratches are all circular when that's not the case

[CharlesW]

Re: Swirl question

Thanks Mike.
That pretty much explains it.
I was well aware it had to be due to optics and the light source, but even then, it seemed like the scratches should show up in the pattern they were created.
Evidently, that is not the case.