Somethings not right. It should be cleaner than that. I do it all the time but i keep the wire above the water. A piece of the relic will stick out and not get cleaned but then you just flip it over and do it again and you will get the entire thing clean. I think what is happening is that its so rusted that the electricity is bypassing the iron relic and flowing from the cathode wire to the anode. I have seen people drill a small hole in the iron and thread a screw in the hole. Now wrap the wire around the screw and hang the thing in the tank with the wire/ screw above the solution. This will force the electricity through the relic.
Good luck