The 6010 and 6011 are the most commonly used welding rods when it comes to dirty, rusty, or painted metal. The reason is their deep penetration and aggressive arc which burns through anything in its way.
E7018 electrodes contain a thick flux with high powder content and are one of the easiest electrodes to use. These electrodes produce a smooth, quiet arc with minimal spatter and medium arc penetration. Many welders use E7018 electrodes to weld thick metals such as structural steel.