Reminds me of a $40 safety lunch I went to where the guy spent an hour on how to hold a clipboard. Old timer at your shop is worth ten of these slide readers.

Watched a volunteer scrub a painted sherd with a toothbrush last summer.

Folded plenty of signatures flat before sewing and thought that was just how it was done, till a bookbinder showed me how creasing the fold actually breaks the fibers right where the thread needs to grip. Letting the thread pull the shape means the paper stays strong at the spine and the section still opens fine once it's bound. Took me a few books to trust it but now I crease after sewing, not before, and the old guy was right.