Each large format printer should be operated through a RIP ( raster image processor ). The key to accurate color communication starts with a calibrated monitor. Some large format printers self-calibrate. The ones that do not are calibrated using third party software and hardware. In your applications you set certain parameters in the Color Settings dialogs. There are basicly two large format print mediums: 1.) photographic, and 2.) graphic arts. At some point, you may want to dedicate certain printers for photographic printing and others for graphic arts printing. Graphic arts printing requires color accuracy and the ability to come close to some Pantone Spot colors. A RIP will help a lot with that. Photographic printers can use their standard drivers for photographic processing. A RIP should optimize the color for you in that it will have the ability to access print tables already established for Postscript Level 3 color output. This is very complex and it may take some trial and error before you have a rock-solid foundation established for consistent color output. There are vendors online that will calibrate your printer for you for a fee.
" If the image isn’t printed with a pantone formula-what would you recommend I do to ensure that what I see on my monitor and what prints are true colors? Can I still do a swatch for reference? If so, how would you recommend that I do this?"
If your customer's file has a Pantone spot color, you can either convert the color manually or let the RIP do it. If you allow the RIP to convert, it has to have the ability to do the conversion. What I do is prepare swatches using Pantone's conversion numbers as a guide. You should also refer to Pantone's swatch book printed conversion samples ( Solid-to-Process Reference Guide ). It is strongly recommended you do not use the monitor for color reference. Use reflective media for reference. Print test prints using 5 percentage variations ( CMYK ) and use that as a reference to which equivalents come closest to a printed reference chip.
Also, you could request customers supply a hard copy contract proof. In cases where they refuse, run a smaller version to surplant a contract proof. The key is getting a customer sign-off before you print the final piece. If the customer signs-off on the smaller proof, then you have a target of what they are expecting. Hypothetically, you'd run the file(s) through the same RIP so the final will match the proof. This trumps anything they see on screen vs. what you see on your screen and pulling your hair-out trying to get things to match. The proof process is critical to eliminating a lot of miscommunications that could crop up without one.