What causes these? Are they inevitable? Thanks.

 

they are caused by numerous sources-
anything that rubs against your finish is a potential source.
you probably will find that your goal is not to eliminate them, but to minimize them. even those of us who really work at not having any will get them and have to remove them every couple of years or so (which means that anyone else will be doing this more like once a year or so).
they are very small scratches in your clearcoat-
does this help?

 

btw, very good answer to your question is at:

http://autopia-carcare.com/autopia/inf-swirls.html

 

Swirl marks will catch the light from almost any angle. This makes them very noticable. When working on you car, always move your hand in a straight line. Don't move your hand in a circlular motion, think bumper to bumper.

Don't use cotton towels on the painted surfaces of your car. Use a good quality Microfiber towel with a blend of 70/30. My current favorite MF towel for detailing are from http://www.pakshak.com/

 

[QUOTE]Originally posted by StwoK

 

yup, even a chamois can cause swirls if you arent careful (if you use it before it is softened, for example- or if it is not clean).
big blue is a better drying solution-
soft and very easy to wash. i wash all of my mfs together after a detail. i dont use mfs for really dirty areas- (under hood, under car, etc.)