I finally found a way to get all the purple film off of the DVD piece that I use as my diffraction grating for the spectrometer, so now it is as clear as glass! I re-did the resolution calibration to make sure the DVD piece is aligned correctly.

This is exactly how to remove that purple residue in less that 30 minutes without damaging the DVD piece, 100%!

I used a 30 percent solution of acetic acid (the substance that makes vinegar what it is) and filled a 150ml flask with about 20ml of the acid, put the DVD section in there and waited for 20 minutes and using latex gloves (acetic acid at this concentration, WILL cause severe chemical burns to your body!) removed it and rinsed it thoroughly under running water and it was perfectly clear and still operates the same.

I just thought I would share that little tricky hack with ya!