Alatina

Have you ever coated the surface you want to keep clean with flux? This seems like an obvious answer but Borax is awesome for this. The best way is to use it like you're forge welding--heat to orange, remove from fire, brush off scale using a steel brush, coat liberally with borax, then return to fire and heat to yellow or desired working heat. The borax will bubble and liquidize the oxides, and when you remove the iron the remaining scale can be brushed off easily. Just remember that since the scale is liquidized, it no longer flakes, but splashes at you when you strike it, yum.