I'm still confused so lets see if I have this right
The best (shiniest) Chrome is Triple Chroming, the object is cleaned in acid which strips it back to bare metal, its then copper plated, polished, nickel plated, and then a single (thick?) layer of Chrome, and polished again, possible with other polishing between process's.
Dull Chrome misses out either the copper layer or the nickel layer, or it has both but misses out some of the polishing?
After the metal is stripped, it is rough and if it was rusty, it's full of pits. It has to be polished or even filled with metal then polished before plating. This is done no matter what finish you want. What makes Dull Chrome, dull, is the dull nickel process. If I remember correctly, the nickel tank has to be heated. Whether it's this, or a different chemical in the tank, that makes the nickel a matt finish, but still over a smooth surface. The chrome over it changes it to a silver colour. No blasting etc is used to get this finish.
Its a difference in the nickel solution that determines whether its bright or dull. Can't remember the details and I lost my Canning handbook a long time ago.
Original Norton dull chromed parts were plated over a machined finish. There was no polishing involved...and the blue/grey finish is still visible, un-rusted on eighty year old parts. This was no wanky modern bright chromed finish dulled down. It is something different altogether and whilst some chromers come close on the odd part, none can do it consistently and none can effectively say why. To my mind it has to be a process that was banned in the 1960s. It was carried out by men in green-stained leather aprons but we can't ask them as they all died young - It was a pretty horrible process evidently.
Thanks Dean, I wasn't sure. I know the tank has to be heated and that takes ages. My mate has taken me round the place every time I've gone there, and he's explained every step to me, but remembering it is my problem :relaxed:
Rik, the process I'm describing is for re-plating a part. If the part is new, the surface is good anyway and not rough like it is when the acid has stripped off old chrome and etched the surface. When I first had some parts done, I said I don't want it polished or shiny. My mate tried explaining to me it had to be polished, so he got my kick start lever and dull chromed it without polishing. It was full of pits and looked awful. He'd made his point and said do you understand now..? :laughing: It didn't look bad when I gave it to him, but the acid takes out any rust and leaves a pit. So the main problem that I've found is how far do you go with polishing out the pits, you can end up with parts looking deformed. It's a bit of a compromise with rusty bits. Or you can spend a fortune filling in every pit, which he did for me on some Mazak Norton Domminator tank badges I had re-chromed. It took him hours.