I've always had trouble with K3b.
As an alternative I use XFburn and it blanks the cd as it's burning the new image.
http://goodies.xfce.org/projects/applications/xfburn
I'm not sure if there is a cmd or a tool for checking a blanked cd and if the blank was done successfully. I looked online for one and didn't find one. -::-Others may know.-::-
If you'd like to use the cmd-line to blank a cd you can with:
Code:
unmount /dev/cdrom
cdrecord dev=/dev/cdrom blank=fast