I figured out a way to paint the new fender flare welting. Everybody who restores these cars tends to paint them the same color as the body which is incorrect. The welting material was originally supplied in bulk as a white latex-like material (on the white cars). They were installed at the factory that way, unpainted.
Since my old welting is petrified beyond useability, (that's them on the right, in the photos), and the new welting comes light grey, I ended up using white interior vinyl due. I cut the pieces to the correct lengtths, trial fitted them on the flairs, then removed them and over a period of several days I lightly misted the individual sections of welting until they were very thinly covered in white. They are now extremely flexible and should work out fine. The problem with painting the welting (other than being incorrect) is that even with flex agent, they will crack at the severe angles the welting has to conform to.
Here they are just temporarily press fit to the flares for storage purposes, and so they get a "set" for their final positioning.