Wrapped up Volume 3 of Les Mois a few days early. My Golden Digital Gel Medium expired leaving a gloppy mess on brush out. I cut a new piece of bookcloth then sprayed on two light coats of Krylon UV Archival 1378 Matte, allowing it to completely dry before printing the cover with the Matte Black inkset. After the printing completely dried, I fogged on a light protective coat of the Krylon. Works well!
[Edit] Not being satisfied with my executions of the drop spine binding, I made subsequent dummies to discover the errors in my thinking. The correct measurement for locating the mountain score in the endpaper is: the width of the hard spine "+" one spacer, as measured from the center of the folded end paper. The mountain score is best made in endpapers "before" gluing up the text block. The additional width for the mountain score, a more precise measurement in cutting the hard spine, and a more thorough burnishing of the liner strip down into the spine spacer grooves seems to have solved my problems. Now I can concentrate on the usual gremlins ; ]