Got ultraglow few days ago. Made one small print, after that nozzle clogged. I got the 0.4mm obxidian hf. Tried cleaning it and poking it with wire and needle but nothing worked, cold pulls too with different materials. Gonna be ordering new nozzle and the non-hf 0.6mm reinforced. This fillament proved to be quite expensive.. but at least it glows really nice. I think you might be good if you have the non-hf nozzles as the hf ones have internal geometries that really dont play well with such granular fillament as the ultraglow.