Thank you for the response. The thing is I was not asking about paints - I was thinking about technique. As I said scale effect means if I simply paint it brass/copper it would look like a shiny little toy. (Real metal surfaces do not look extremely shiny when looked from afar, unless they are polished to a high sheen. I am not certain the Nautilus would be polished...)
So I was wondering about the application of paint.
First off, it is cool that you are doing the Pegasus Nautilus - I have that kit in my stash too, and it looks to be a beauty!
As for the application of a “brass” effect, I would start by priming the built ship with black enamel to provide a “shadow” base. Then, apply a misted (but fairly thoroughly covering) coat of gold/brass acrylic paint, perhaps cut with a little flat gray or brown to dull it down. This should be mostly airbrushed from above to leave hints of little dark shadows beneath the rivets and other surface details. Then give the ship a wash of thinned Burnt Umber (a dark brown) artist’s oil paint, as brass tends to oxidize to a dull brownish-gold hue. I recommend artist’s oils because they are finely ground pigments, will not react with the acrylic base color, and in addition to outlining details will leave a nice filter effect to “brown down” the brass overall. I’d also add a second, lighter wash with dull, pale green oils to depict the oxidation of the copper component in the brass. Some darker green can be applied as well as to suggest marine growth. After that, some very discreet drybrushed touches of your base brass color here and there would be good to emphasize the unpainted metallic look of the vessel. As a final step I’d apply an airbrushed flat to semi-gloss clear coat to blend the whole and reduce the shine to a suitably muted, scale metal patina.
I wish you the best of luck with your steampunk sub!