Weird effect of various DVD-R Discs

[PurpleMan]

when you burn on a dvd-r disc, it changes the color in the area on which you burned. for example - dark purple when the disc is blank becomes lighter purple after the disc is burned.

I have found that on certain discs (especially ritek and other very-dark-purple-surface brands) - after you burn, there are some spots in the middle of the burned-area that remain in the original color.

These spots/marks on the burned discs would, to me, logically, indicate that the areas in question were not burned, at all.

However, all the files are perfectly readable.

does anyone know what causes this and if it's something that should worry me?

P.S.
This might not be directly relevant, but in the last disc that this happened on, the 'non-burned' spots were in a place where the data-surface had a finger-print.

[fOZf8]

From what I have heard, that could mean that the burner isn't able to keep the laser calibrated at the needed power to burn deep enough....it could also possibly be the media, but what you describe is exactly what happened to my DVR-A03 last month as it was in the process of dieing a long slow death.

[PurpleMan]

actually, it's a 3 months old burner (LG GSA-4120B)

and it only happens on some medias specifically.

and yet, the disc is completely readable. no errors.

[smiller667]

I would assume the laser scatters at the fingerprint stains and thus doesn't "burn" the dye layer with the correct intensity.

Alternatively, you can onbtain this effect by having dust particles on the writable side of the disc ... if these spots are small enough, error correction will take care of it.

Steve.

[Surf]

"...it's something that should worry me?" Not if it is your last will and testament :p . Seriously, if the movie plays normally then adopt "what, me worry?" attitude.

[theReal]

This might not be directly relevant, but in the last disc that this happened on, the 'non-burned' spots were in a place where the data-surface had a finger-print.You should avoid at all cost getting finger prints on the media before burning!!
Before burning I handle discs with extreme care only - the surface must be shining clean, otherwise you have the risk of unreadable sectors!