I have no issue going the full distance on CMYK separations , that for me is the easy part.

Devils advocate now... you mention the carbon process as most likely the most archival... All of my research points out that the pigments whether carbon, gum and to the extent of hand pull gravures could use the same pigment sets, or it is possible to use very similar.

Carbon introduces a gelatin support , the others are slightly different and in what the pigments are being spread onto the paper with.

so with this in mind what different characteristics are in play that would make the gum pigment process less archival or even the ink pigment process less archival? Is there factors in place that I am not aware of?

Quote Originally Posted by Hexavalent View Post
Bob, "carbon process" is likely the most archival process, IF the pigments used are non-fugitive, the support is durable, non-yellowing, etc., etc., There are likely polymers other that are more stable than gelatin (even PVA glue can be used for "carbon transfer").

Going the distance to full CMYK separations takes colour to a whole new level, in both effort and results. Not for the faint of heart! Carbro, rather than ordinary carbon is the usual route for "high-end".