PMS Explained - No, Not That PMS!
PMS is NOT colors with a bad attitude! PMS stands for "Pantone Matching System" and is a universal color standard used by printers and graphic designers to achieve some kind of consistancy in color usage.
Each color has a number that appears in a Pantone color swatch book and we can mix the basic colors to match the PMS #s. There are currently 14 Basic Pantone colors plus the four process colors. The Pantone books show colored swatches of all the mixed colrs with the formula printed underneath it. For example, PMS 320 "Teal" Green is made by mixing 8 parts Process Green with 8 parts Pantone Green - 50/50 mix. Other colors can be more complicated using varying proportions of up to four of the mixing colors to give the correct PMS color.
What you see as red and I see as red may not be the same red! That is why we use the Pantone or PMS system to specify colors. Using the PMS system we can all be sure we are talking about the same red - or blue, green, or chartreuse, etc. Wherever you go in the USA and the rest of the world, if you specify PMS 185 Red, you should get the same bright red.
The paper that the color is printed on will affect the gloss and intensity of the color. Gloss paper will help it to reflect light. Matte finish paper will give it less reflective, smooth look. Colored paper will change the hue of the color and possibly darken it. Also the amount of ink run on the printing press and the porosity of the paper will change the intensity of the color somewhat, as it dries and is absorbed into the surface of the paper.
The system isn't perfect because human beings are involved, so don't expect an exact, unvarying color-match all the time. The printing press, the press operator, the paper, the kind of printing plates used, the weather and humidity, the brand of ink, all of these factors can cause very subtle differences in the look of the finished piece. Variations of shade and strength of color of 2% - 3% can - but may not - happen, so be prepared! A job printed in January may look slightly different from the same job printed in July.