I thought some of you might find this interesting. I was getting a lot of spots from time to time on my dvd-r. I now know that it is due to dust and foreign matter on the dvd. I actually found a particle of something on a finished dvd and when i cleaned it off, there was a spot below. I guess it was due to my own carelessness but anyway, these spots are not causing any problems for me on playback that i can tell. This was worring me a lot. I did not know what was going on or if the dvd-r were damaged or not. I actually did a little experiment to try and see how bad I can make the dvd and still have it playable. I took three pieces of hair and tied them on a blank dvd-r so that they all ran from the center of the dvd to the edge. I was hoping that this would cause a spot to appear but in a continous line from center to end. I then placed numerous finger prints on the surface and a few foreign particales as well. I burned the dvd and when it was done I got the result i was expecting. The hairs caused lines and the finger prints/ particles caused spots. This verified for me where the spots were coming from and what was causing them. My only concern nw was how would this damaged disc be affected in playback. I figured if I got a line from center to end it assures me that I will hit the dot when playing the movie. It gave me a way to be sure that the dot, in this case a line, would surely be hit upon playback and made sure that the dot was not in a part of a disc that would not play with the main movie. The disc looks pretty beat up. I have pictures if you are interested but like I was hoping, the dvd played fine. I really beat this disc up and it played fine and I know for sure that I am hitting all three lines right from the opening of the movie.
That could have been a costly experiment, do u know HOW close the pickup unit (laser)sits to the surface of the disc? VERY CLOSE, do not know exactly but if u had lets say abit of grit, this would scratch the surface of the pickup permanently (Dustbin time) Still interesting experiment though.