The science be hind swirl marks

[Thejoyofdriving]

I noticed the other day that some furniture in my house had swirl marks in them, i thought that swirl marks were caused by improper use of rotary buffer or improper washing, and i surly dont go over my table tops with a PC or wash them! so if a table top has swirl marks, than how do cars that have not been buffed with a pc or washed with a circular motion get swirl marks? when i inspected the paint on my table top i found the small scratches not to be in circles but more straight or diagonal, but when i moved into the light they magically turned to swirl marks, why does this happen to paint? how can swirl marks be caused with out a circular motion?

[Mike Phillips]

Re: The science be hind swirl marks

Pretty simple really...


Anytime anything comes into contact with a delicate, thin coating like paint, no matter what it's on, the potential exists to scratch or instill a scratch into the finish.

[Drake]

Re: The science be hind swirl marks

Mike, your answer is fairly broad, and does not address his question of how straight scratches look like swirls on his furniture in the light. (or on auto paint for that matter). The answer is only simple if one is a physicist, with experience in light refraction. Since I am not an expert in the field, I will not
try to explain the reason, however a quick search on the net will reveal all.

[Ryan L.]

Re: The science be hind swirl marks

Mike, your answer is fairly broad, and does not address his question of how straight scratches look like swirls on his furniture in the light. (or on auto paint for that matter). The answer is only simple if one is a physicist, with experience in light refraction. Since I am not an expert in the field, I will not
try to explain the reason, however a quick search on the net will reveal all.

Like you said, it is all in the refraction of the light, and how your eye sees that light reflecting of the of the surface.

[9C1 MAN]

Re: The science be hind swirl marks

Pretty simple really...


Anytime anything comes into contact with a delicate, thin coating like paint, no matter what it's on, the potential exists to scratch or instill a scratch into the finish.

[the other pc]

Re: The science be hind swirl marks

I think you can split the "science of swirls" into two broad categories, how the swirls are created (mechanics and material science) and how we see them (optics and human visual perception).

Before you can get into any in-depth discussion on a topic you need to have consistent terminology. Otherwise you can't be sure that everybody's talking about the same thing. When you study a science like chemistry or physics you start out by learning the fundamental definitions and principles then build from there.

Unfortunately, there are no "official" definitions in the detailing world. So talking about things can get confusing pretty quick.

Here's a thread where we talked about swirls a bit.
The Swirl Mistery


PC.

[dietoremain]

Re: The science be hind swirl marks

Im glad I drive a white vehicle, hides swirls way too good. haha.

[Michael Stoops]

Re: The science be hind swirl marks

I noticed the other day that some furniture in my house had swirl marks in them, i thought that swirl marks were caused by improper use of rotary buffer or improper washing, and i surly dont go over my table tops with a PC or wash them! so if a table top has swirl marks, than how do cars that have not been buffed with a pc or washed with a circular motion get swirl marks? when i inspected the paint on my table top i found the small scratches not to be in circles but more straight or diagonal, but when i moved into the light they magically turned to swirl marks, why does this happen to paint? how can swirl marks be caused with out a circular motion?

If the furniture has ever been dusted with a towel, rag, etc then the potential exists for a scratch to occur.

As for swirls being in a circular pattern, have you noticed how the "circular patter" is always "around" the light source? That is, if you move the light source 6" to the right, the center point of the "circular pattern" moves with it. That alone should tell you that these very fine scratches are not truly in a "circular pattern" but are refracting and/or reflecting light from a pinpoint source. Shine a flashlight onto any surface in a dark room - the center point of the light will be brighter than the outer edges. Now shine a light on your paint and you'll see the intensity of the fine little scratches fade as you view them further and further from the center point of the light. Keep in mind all the while that these scratches are exceptionally tiny in depth, it's just that the sharp edges of them reflect the light so well. Polishing not only removes some of the surrounding clear coat, but also just rounds over the edges of these marks. Take away the sharpness, whether you remove much surrounding clear or not, and you take away their ability to refract and reflect. Sort of like how a prism, those triangular cross sectioned bars of glass, will split sunlight to show the full spectrum of colors, but a flat sheet of glass just lets the light pass through it.

[Thejoyofdriving]

Re: The science be hind swirl marks

Hum, i have noticed what you are saying mikeinorange, i just would like to know why. thanks all! i have searched the web but i have not benn able to find any thing.

[the other pc]

Re: The science be hind swirl marks

Did you read the other thread? Are you asking about swirls or spider webs? The physics behind them is a little different.


PC.

[Thejoyofdriving]

Re: The science be hind swirl marks

swirls

[the other pc]

Re: The science be hind swirl marks

Swirls are groups of parallel microscopic scratches. The perceived visual image of any individual scratch is dependent on the geometry of the scratch (width, depth, shape, length, etc), the visual acuity of the human eye, the orientation of the scratch relative to the observer and light source and the geometry of the light source.

As you look at a scratch from different angles and distances the image of the scratch will change in apparent size, shape, intensity and so forth.

As your distance to the swirl increases your ability to visually resolve individual scratches decreases. You then perceive the swirl by the aggregate image, a combination of all its parts rather than as a group of individual scratches.

But the image of each scratch still changes as you move about so the combined image will also change with different individual scratches contributing variably to the whole image of the group depending on the overall orientation. So the whole image changes.

The position of the observer and light source as well as the contours of the scratched surface all play into the visibility of the individual scratches and therefore the combined image. So the final visualized shape of the combined image is a complex interaction of the many pieces.

If you look very closely at the computer monitor in front of you (you may need a magnifying glass) you'll see that the letters that make up these words are actually formed by thousands of little dots. My monitor is an LCD, the dots are square. But the letters C, S, Q and so on all appear to be curved. They can't really be curved because they are made from squares. They just look curved because my eyes perceive them as a group.


PC.

[Thejoyofdriving]

Re: The science be hind swirl marks

That is what i was looking for thanks