Weigle Frame Saver is some sort of (undoubtedly toxic) liquid that gets sprayed inside a steel bike frame to ward off rust. Once there, the liquid turns into some kind of (undoubtedly toxic) sludge that coats the insides of the tubes. Today is expected to be the only day warm enough to apply it before I plan to start the build, so I did.
It's a simple process; I'm linking the video below instead of explaining it myself.
Besides, he's way better-looking than I.
Anyway, the frame and fork are out on the back patio, where the toxic sludge is outgassing.