Quote Originally Posted by ogorir View Post
It looks like porosity at the tie-ins, to me. if you don't get a new rod going before the slag puddle cools, you have to chip/grind it out, or you get porosity like this. it's less of a worry with 6010/6011, they leave thinner slag and burn out more crap than 7018.

+1 on the slag indicator of heat, too. if you watch a couple of Jody's vids (at weldingtipsandtricks.com), there's at least one that he chips the slag off with the butt end of another rod. that's how easy it should come off. this vid @ about 8:15 http://www.weldingtipsandtricks.com/stick-welding.html

[edit:] I just noticed that Jody's 'backstepping' technique is tieing into cold slag. he doesn't seem to be getting porosity, but I've had issues with it before.
you can tie in without cleaning the slag off, but you have to be careful as ya, you can get porosity, slag inclusions and other crap in your weld. usually if im running a few beads or whatever and my base metal is still hot, i usually wont worry about it. i dont allow anything to really cool, just pull out the burnt rod, slap a new one in and keep going. i also run fairly hot with 7018 all the time so it helps to burn that crud out.