No, the iron mask doesn't work if you have it turned off, if off then the program
screen is activated.
If you have the XS, I think the factory preset is -6 on iron mask.
If you want to knockout most small iron, -12 should do that.
In fact -12 should just about knock out all iron items except
for iron bottle caps and maybe some big iron that could bleed thru.
If you have gained some experience with the Explorer at -5 or -6 and
want to lower that setting then -12 or so could be a good starting point.
If you have wet ground -15 to -14 will allow some nails to chirp.
-13 seems to cut out most of those chirps in wet ground.
This goes for the XS in my conditions, I don't know about the other Explorer models.