Understanding Inks Used in Offset Printing

When you view the printer setting of on your monitor, you will notice four colors.   Some would probably identify these are blue, pink, yellow and black.  But a trained can easily tell that they are actually cyan, magenta, yellow and black.  These four colors make up the CMYK color space which, in turn, make up the four-color process used in offset printing.

This is the image color space used in printing, as opposed to the RGB (red, green and blue) model used in computer monitors and LCD screens. 

The four colors in CMYK can actually produce a wide gamut of colors that has enough to correspond to the colors in your images.  The inks are mixed at different concentrations to achieve hues and shades far beyond the number of these four basic colors. 


Process color and spot color

Printing in CMYK is also called process color printing.  As mentioned, the three primary colors plus the key color black can produce countless other colors which result to full color prints, and at consistent quality at that.

However, there are times wherein process colors are not enough to accurately copy the shades of an image, and may even alter the quality of the printout, as in the case of logos with very unique colors --- the hues that provide the identity of these logos.

For occasions like these, additional color may be required apart from the basic CMYK.  The fifth color is called a spot color.  Each spot color has a very specific shade.  The most popular brands are Pantone and Trumatch. These two have color matching systems that allows you to print image colors with precision.

Companies who manufacture these inks come out with swatch books or color charts for these spot colors annually.  Your printer most likely has one so you may request to view it.  Or if you can get hold of the company, you can ask for your own color matching system guide.

It is important to note that the inks differ in quality depending on the properties of the paper.  An ink would look different when printed on different surfaces.  For example, a certain spot color would appear differently on uncoated paper, as opposed to printing it on coated paper.  Swatch books have a provision for this concern.  Their spot colors are coded to indicate if the particular color is printed on uncoated or coated paper.  This way, clients can make a better decision on ink selection and acquire higher accuracy in achieving the unique shades.

The same goes for printing on colored and plain white paper.  Expect the hue and quality of colors to change with the inherent color of paper you use. 


Special effects

With the Pantone Matching System, specifically, you can add various effects to your text which cannot be achieved with the basic process colors.  These special colors include metallic inks which provide a shimmery effect on texts, pearlized inks that give a glittery appearance, and fluorescent inks which have strong and striking luminescence.    These effects are one of the clear advantages of spot colors over process colors in offset printing. 

The downside of spot color, however, is the cost.  It may make your offset printing project significantly more expensive.  Plus there’s the slight inconvenience of informing your printer beforehand that you will be needing spot colors so they can order the inks.  Weigh whether you can adhere to the basic CMYK color process or if you really need to use spot colors so you can review your ink options early on.