Anti newton glass from the slide mount does work. You need to use the AN glass , not the plain one, and you need to use the AN side of the AN glass. Lightly drag a razor knife over the glass to detect the AN surface. You have a 25% chance of picking it right the first time. The surface will sound rough, but you will not damage it.

I made a AN glass top that way for my D6 35 mm carrier and it works fine. Do not try cutting the glass. Just file out the top to size. Go slowly are carefully. It will take several hours .

A thin spacer also works.

Tried the spray decades ago without sucess.

When you mount a slide, the AN glass goes against the base side only, clear on the emulsion side. Enlarger carriers are made the same way.