The part is intended for use in an ultrasonic bath so I can remove dirt via this route without difficulty, I need to physically remove stainless steel from the part.
On reflection probably sulphuric acid at lower concentrations would work, that would be safer, but still the topic of this post is "Electro-polishing kit". The reason there are no kits is because its not the sort of thing that should be done in a shed and whoever supplied them would get sued into bankrupcy by the inevitable accidents. I've made a list of electropolishing companies to contact along with microcut, one of them will do it for not much money, its just a pain finding the right one, and if I could do it myself safely I would.