Re: Making use of the higher Gamut of CcMmYK press work with RGB files
@ Russel,
Most CcMmYK printers were designed to use 6 colors to make smooth transitions requiresd to make images natural, not for 'higher gamut' - for example, if one only used the black ink only in a drop shadow - where the drop shadow travels from 35% to 0% over 10 to 15 pixels, the viewer would notice that it looked "peppery" like someone tried to shake pepper - noticeable little black dots spaced far apart from each other - instead, they use small amounts of cm and Y to make it smooth. One of the double colors is for the highlight area - a lighter tone of that pigment - the other for the darker.
But I think what you are asking is "can I get a higher gamut in my images if I submit RGB instead of CMYK?" This is always complicated - just ask anyone who works with Pantone Hexachrome - you need to rethink everything. Flesh tines, grey balance - unless you are doing something exotic like a tropical bird catalog, I wonder why you are unhappy with your current situation - are you comparing your piece to some other piece ? Was it UV coated ? Was it on nicer stock ? There are many reasons people are unhappy with a printed piece - know that the JCPenney catalog is done using SWOP 3 CMYK - it is often more about good tone reproduction than 'higher gamut' printing.