Coatings on DVD

I have backed up a hand full of my DVD’s using DVDfab Plat with no problem until the other day. I usually compress the DVD’s down to a single layer disc. My 2 burners are a SONY DRU820A & a NEC and they are both DL compatible.
Here is the problem. I BOUGHT some DVD’s from a local library sale, and they seem to have a coating on them. Some have a fine coating spray (yes I tried carefully washing it off) and some are like a wide tape(no seam). It will read to the HDD fine until about 43% and then it will go real, real slow like about 0.02 mb/s which will take about 15 hours to finish the read. Then the burn takes the usual 6 minutes but the finished back up when played is horrible. The original discs with the coatings are not scratched up bad but I still want to back them up with a copy. Any advice?!? Thanks!!!

is this over the disc?

Have you tried ripping before trying to remove the coating? There are coatings available to fill in scratches. I have never used any coatings, but when I read about them they appear to be permanent. Anything that would remove these coatings would probably damage the disc.

You might ask the Library what they use, then see if they will allow you to read the label. Write down the Brand, manufacturer, and ingredients. The first ingredient is usually the base and will determine what may remove it. Also google the the information that you obtained. Most coatings and paints will usually soften their products. I learned that when I had some dried up paint brushes.

For real slow reads, check and or reset your DMA settings. I used DVDFab to read a DVD-RW that had some reading problems. During the read/retry my system somehow turned DMA lost. I noticed this after I trashed that bad disk and starintg ripping a disk I now was good. Love the Rest DMA that was added to Fab.