I feel it's the most thorough method of cleaning. As long as you don't overdo it (see the previous discussions about "hydrogen embrittlement"). Some people feel they can leave a piece like that for weeks just because you "can't overdo it"; while it won't eat into good steel as an acid would, you don't want to risk catastrophic failure just because you were lazy. Baking a piece after the process is complete will eliminate hydrogen, but it will escape on its own in time as well.
Also, make sure your wires don't touch (I've seen downright dangerous setups), the area is well ventilated and don't use salted water or some other things I read about as a catalyst.
I feel like you'd want the piece ungreased first, especially if you are going with a lower current. I used the 12 V terminal from an old computer source and I was happy with the results. Using a +12 V with a -12 V one gives you 24 V. And keep away any stainless steel from your tank.
Watch the polarity, you don't want to rust your axe head further
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I wish I could show you a nice head I cleaned up but in the mean time it gained a little bit of patina back. Anyway, if this is the first time you do it, don't expect your stuff to come out of the tank shining...you will need to scrub some nasty black stuff off of it. It comes off very easily. Try not to get it on your hands, though, it's hard to scrub off afterwards
. Oil the piece generously as soon as possible - it will start rusting at an alarming rate
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Here's my unsolicited contribution, instead of that nice pic
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. It does look like mad science "from outside looking in", as if Frankenstein's monster missing from the pictures. But it works beautifully.