When scanning my 4x5 negatives, I like to place them on the Epson Fluid Mount Holder and place a piece of Picture Anti-Reflectant glass on top of the negative to keep the negative perfectly flat.

I always place the emulsion side down so it faces the scanner optics and then place the glass on top of the negative, etched side down.

I have read that Anti-Newton Ring glass is the suggested method but its pretty hard to find here in the UK and I am wondering if using this picture anti-refectant glass is compromising the scan by not using Anti-Newton ring glass.

Not sure what the difference is to be honest.