Colors vary within a range when it comes to t-shirt printing, but the best way to communicate the color to the printer is by referencing a pantone color chart. Here is a link to a pantone color chart that I found online. Pantone color charts are a necessary tool and everyone should buy one of the books that show swatches. If you are doing artwork on a regular basis pantone color matching is a requirement, especially for a hard copy printing, but for a one-time deal pantone color chart should do the trick. Pantone Color Chart online for Pantone Colors. Here is a link to the official Pantone website in case you want to buy Pantone Color Matching Guide or Book online. Some printers can match pantone inks by formula, but you must always keep in mind that the color of the shirt and type of ink may dry and look different on an actual shirt. Always allow or for one or two hues / shades difference in a design.
Screen Printing Inks and Pantone Color MatchingYes and No. Yes t-shirt printers and match pantone colors and many have complex systems and ink mixing machines that help with the process. However this is only reasonable for large jobs. I've found that even when you do match a pantone color for a print job the inks can look different wet than dry and surprise it's still not exact. Also the color of the shirt next to the ink can affect your eye which changes the perception of the color. Mixing a pantone color for screenprinting also must take into account that the person using the pantone book should use Uncoated reference chips and not coated. Screen vibrancy is nothing compared to flat cloth, so don't think that a backlight design shown on a computer is going to look the same. In fact, I think it often looks better in ink on cloth, but that is a matter of opinion. Pantone numbers are great references for screenprinting but they only put you in the ballpark. Always think of pantone colors as a range of colors or as a reference for the rest of us. The final result will be hue on one side of the color or the other. Paper printing is different and Pantones were created for that industry, which explains the difference. Screen printing is like starting a fire with two rocks compared to the detail and accuracy available in offset printing.