I would not recommend welding through ZR as it will contaminate the weld as would any other paint, rust or grease. I have had to do some fab rework on my frame after I painted it with ZR but I use a wire wheel to clean the area first, do the rework, remove the weld splatter/flux, and then repaint the area using ZR from a rattle can. The ability to retouch areas when using ZR is one of the benefits in my opinion. I like the stuff.
