I am experimenting with double coating platine right now. The first coat of ferric oxalate, palladium, and NA2 is diluted to 50% with distilled water. Once that is dry I am doing a second coat with a 100% ferric oxalatealladium solution. The first try clearing right now, but looks really great wet (dont' they always . . . ).
I will throw up some scans of the sharpness issues as soon as I can.