What I would like to know is how do the separate emulsion layers stay separate during the coating phase?

Are there additives in each particular emulsion layer that prevent mixing (different specific gravity)?

Or is it that you can just layer one emulsion on top of another, providing you chill the emulsion stack very soon afterwards that the layers remain separate before mixing has a chance to occur?

Did we cover this already in this forum in another thread perhaps?

Thanks,

Bob M.