Tri-city did my 68 rear bumper. I shipped it off to them by FedEx and they sent it back restored around three months later. The restored bumper looks better than it did on a new Firebird in 1968. I am very happy with the quality of their work.
Plating is more involved than dipping the bumper in chemicals with the electricity on. Minor defects have to be straightened. For instance, if a bumper jack has ever been hooked onto the slot, the damage here will be resored. Pitting on the show side needs to be filled and the show side of the bumper needs to be made optically perfect, like a mirror.
A good plating service will highly polish the copper layer after this first plating step, which is plating on the copper cladding. Quality depends very much on how well this step is done. Polishing and working this copper layer to optical perfection is necessary for show quality results. It is labor intensive and key to perfect results. If you think about this, you are seeking mirror smooth perfection. Just like with paint, that begins with the early steps.
It is expensive work, but this is an instant of you get what you pay for.
