Originally Posted by DominikDUK
Dark almost black sky maybe not but by using a pyrocatechin based developer you can forego a yellow filter. Silvernitrate is only sensible to blue and ultraviolet light cutting the blue spectrum will result in a very very slow or very very grainy emulsion. Dark near black skies can also be achieved by burning in the sky at the printing stage.
Pyro stain has nothing to do with the spectrum of color at time of capture
Dark skies are best made with filtration. Extreme burning is harder to control and results in very grainy results. Orange or red filters, and possibly a polarizer if not too wide of an angle, are much better choices for this.
Personally I was really hoping they would release SFX in sheets. I am exactly 0% interested in any of these products.