f82r - label x + St Catherine

[Jorge_Stolfi]

I am always surprised at how different our results are. This is how I see it. Quimu's sketch is correct.

I am no expert on the matter, but my analysis is based on all I know about the way vellum is made, and a close examination of the image.

From the latter, it seems that the stitching was not like that sketch, but with the two lips mostly flat, with zigzag thread:

       

The image at left is how the tear on the vellum must have been stitched while it was still being stretched, smoothed, and dried.  Orange is thread on top of the vellum, blue is thread below the vellum.  The stitches not shown are uncertain.  The thread must have gone through some holes more than once.  In particular the stitching had to be secured by knots at the top and bottom.  

Again: once the vellum was dry and removed from the stretching frame, the thread was removed, the lips were pounded as flat as possible, and glued along the edges.  Then the tear and the holes were plastered with a mix of glue and chalk.  And then the area was lightly sanded with pumice.  

This plastering and sanding was the standard way to remedy defects in the vellum (although most were smaller than these).

Over the last 600 years the plaster fell off from the holes, and partly from the lips.  But some still remained.

The evidence for the stitching being as shown above left is in the details of the image at right.  Where the thread went under, the vellum remained slightly raised, and where it went over, the vellum was slightly depressed.  The depressed places are still filled with the plaster (the smooth darker tan spots).  The raised places were sanded clean (lighter streaks across the tear). 

All the best, --jorge