A Basic Explanation of Ink on Paper (101)

Mike Vitamvas of Wall Printing Company recently sent this great explaination of ink colours and how they reproduce onto paper. Hopefully you will find it useful information.

"I want to give you a brief education about ink and how paper effects it. I find I get a lot of questions about this subject so I decided to write this short piece explaining it.

There are two basic ways to make a colour. Most colour standards are set by using the Pantone Matching System (PMS). It covers spot colours as well as colours made by four colour process. If you've ever had the same job printed a couple of times, either at the same place or at two different printing facilities you probably experienced the challenges of the PMS system.

Offset ink is partially transparent, which means that the color you get is going to be partly determined by the color of stock you pick. The same job will look different if it is printed on a cast coated (high gloss coated stock) gloss stock or uncoated stock. That is because ink is absorbed by each of the stocks differently, which affects the colour. This is true if you are using spot or process colours. Pantone books use a standard coated and uncoated cover when they have the books printed. (If you put two pantone books down side by side you will probably get two different colours).

In theory you can make most spot colours out of process, although they will not look exactly the same. Process to spot colours will vary from one printing facility to another. The reason is that there are different technologies for making the dot pattern and different types of printing equipment. Generally the finer the line screen the closer process comes to matching a pantone colour. Another factor that affects the colour is whether the press is running a conventional or waterless system.

So with all the factors, how do you insure that your job looks the way you want it to? I want to tell you it is getting better. Ten years ago almost everyone was using film to make their plates and provide proofs. They were very consistent at least within each printing facility. Then direct to plate started to become popular. It gave advantages such as faster make ready and better plate consistency. However proofs when from anolog to digital and the consistency went down. Today digital proofs can be calibrated to match a particular press and many automatically recalibrate to make sure the colour stays consistent.

There are a number of challenges still to overcome. Toner based machines are getting better but getting them to match the color of offset continues to be a challenge. Also proofing on colours other than white stock is a issue that still needs to be addressed.I hope this information will help you in your understanding of how ink is put down on paper."