humidity causes the geletine to swell more than the backing thus the increase in newtons rings in high humidity due to the decrease in flatness in the film and the resulting irregularity in contact with glass

solutions in regular use for at least 100+ years that will work:

use thicker glass-it weighs more and is stiffer so you get better contact between glass and neg/pos/whatever

use nonglare picture framers glass with texture against film

dust with offset powder-cornstarch

use a vacuum easel without glass

strip neg and/or pos into support flat with or without window-this will make film lie flatter

experiment with emulsion up/down in combination and against glass

use film with retouching surface on on one or both sides

fyi: glass blocks uv, float and plate glass contains iron that turns glass cyan and blocks more uv-whaterver is a poor alt process artist to do????--duh --use plastic

fyi: glass both "water white", window glass, nonglare or whatever has been and still is in use daily for 100+ years in all things photgraphic to produce everything you see in print and on the packageing of everything you buy-yes a gel(itine)filter is optically better than any glass but so what-yes an optical flat is more parallel than window glass but so what-yes a vacuum easel or frame will pull material flat but so what

without skill, technique, craft and knowledge gained by working smarter-not harder-or worse yet, by instead throwing money at a problem all you get is is foolishness-and crafty venders richer and fatter

vaya con dios