Hope you don't mind me asking but going back to your tutorial on applying the rust effects - do you start from bare plastic/metal when you apply your brown undercoat. E.g. if you were weathering a pre-painted diecast would you strip off the original paintjob to bare metal before starting the rust effect process or just give the existing paintjob a bit of a rubdown to key and then go from there? All the best, GDonk.