What are the C and the U?
What are the C and the U after the PANTONE color number? If you have used any design programs like the Adobe applications, you know that Pantone colors are listed by number and most often have a letter after the number, C or U. The letter refers to the paper stock, either Coated or Uncoated. As discussed in a previous post, a coating on the paper allows the ink to sit on top of the paper without absorbing into the sheet. Uncoated paper is just that; paper without the coated layer. It is more absorbent than coated stocks and allows the ink to absorb into the paper.
Regardless, if the Pantone color is C or U, the colors are made from the same formula, but the printed color can look very different depending on the stock! The coated papers allow the ink to sit on the surface so it remains rich and vibrant. The uncoated sheet allows more ink to be absorbed into the paper, giving a softer more muted look.
Many light colors are made with high percentages of translucent white and have smaller percentages of pigmented colors. As a result, coated and uncoated versions of lighter colors tend to match more closely, while darker or brighter colors (which have a higher percentage of pigmented colors and less translucent white) have more opportunity to look different as the darker pigments absorb into the stock.
Some designers will choose different spot colors for their files, depending on the stock that is used. Some designers will even choose different Brand/Logo spot colors based on what stock they are using so their company colors will always match regardless of stock.
Your Julin representative can provide you with coated or uncoated chips of Pantone colors to help you make your color selections if you are concerned with how your spot colors will print.