The technology has changed, but not the basics.
On clear waterslide film especially, the ink's pigment count is going to be your big concern. It may take multiple printings of each color, one color at a time, in layers, to achieve the kind of pigment quality the old age ink's carried in their thicker oil-bases.
Any color printable, black to white, will usually take less ink to get a solid color than a clear printable, because it is already building on the "free" opacity that IS the printable...i.e. the background color.
Background colors can have a huge effect on print, and method choices too. That's because most paint and ink is not 100% opac. Not even your car's. E.g., the primer shade can make a noticable difference on two paint jobs of the same paint. More pigment the only way block the pesky light from penetrating deep, and bouncing the background color back at your eyes.
White is the most common background for good reason. It is used most by near default for more help compiling other color combos from the pure basics, and stands well in contrast too.
The point is, the need for enough pigment to get a perceived opacity will change with color and again with background color. (This includes the bleed through effects AND some interesting border/color/contrast effects ("see a blue dress or gold dress?" kinda stuff ). With white on black, you need as much pigment on the sheet as you can get.
