I don't know if the cylinder was actually metallic, I have seen many photos and it appears as the same colour as the rest of the carriage. I think it is just a cover for a spring and not an actual piston, I could be wrong. Yes, lots of washing and detailing still left to do, this is just the beginning of the process and I still have the limber and anchors to do yet. I don't think that you have to have an airbrush, but it does make life a little easier in some cases, a lot of modellers at my club still paint with a brush only and produce some fine work.
Thanks for your comments, much appreciated.
All the best,