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Question and Answer

What are my concerns when overprinting foil?

by Staff

February-March, 1996
Printing four color lithography over hot stamping foil has continued to become a very popular process for all types of applications, including trading cards, school yearbook covers, software and CD packaging, and other promotional material. The unique eye-catching look has encouraged a variety of businesses to choose this process to increase brand image and product awareness.

Although overprinting foil is glamorous from the customer's point of view, it can be an extremely tricky process if proper communication does not exist from the beginning of the project to the end. In order to ensure a successful project, there are several steps that should be followed.

Prepress
When overprinting hot stamping foil, the opposite scenario exists as in most applications. The foil stamper has the printed sheet first and the printer has it last. This means that the printing must register to the foil stamped sheet. In order to obtain the best registration to the stamped image, it is strongly recommended that the film for printing is stripped to an actual foil stamped sheet. Stripping to the foil stamped sheet can also help to minimize registration issues as a result of die expansion due to the heat and pressure of the foil stamping press. Also, ask your service bureau if they can create a chromolin over the foil stamped image. This is possible and is an excellent way to present your client with a close representation of how the ink will appear over the metallic foil.

Press
There are two main concerns when applying the hot stamping foil before overprinting. First the foil must adhere properly across the entire image area. Although the area may appear to be covered, you may have "soft spots" where the foil is not adhering properly to the paper. The best way to check for this problem is with a simple tape test. Place a piece of scotch tape on every portion of the stamped image and peel it off at a normal pace. If the scotch tape pulls off the foil, most likely you need to build up your makeready in that area to ensure proper adhesion. Second, make sure the hot stamping foil you are using is formulated to be overprinted. Not all foils are overprintable! Check with your foil supplier to confirm that the foil you have chosen will accept ink.

From the lithography side of the project, special inks are necessary to dry properly. Have the printer you are working with speak with the ink supplier about utilizing inks which are compatible with overprinting hot stamping foil. This type of ink is readily available, and should not cause delays in the project. Also, when overprinting foil, it is always wise to have the client press proof the work. "This isn't always popular with clients, but it is your insurance policy against unforeseen problems, and it is the only true representation of the finished product," stated Brian McGonigle, Sales Consultant for The Lehigh Press, Inc. Lehigh Press works on overprinting foil projects almost weekly and understands that you cannot see the true color effect of the ink over foil until the job is on press. Lehigh is in a unique operation with the ability to foil stamp and print in-house, allowing more control over the entire process.

The most important areas of concern when overprinting hot stamping foil are:

  1. Strip the four-color film to the foil stamped image.
  2. Make sure the foil properly adheres to the sheet and that the foil is overprintable.
  3. Choose inks that are formulated to overprint foils.
  4. Always have the client press proof the results.

In addition, several foil options must be considered when overprinting hot stamping foil with four color lithography. The most common foil colors used for overprinting are gold, silver and diffuser holographic foil. Overprinting diffuser actually creates a holographic effect at a more economical cost than a customized 3D hologram. You can also choose to utilize a refractive engraving and then overprint, which adds movement and definition to the image. Whatever type of application you choose, remember that communication and an eye on detail will help guarantee a successful project.

InsideFinishing would like to thank Brian McGonigle of The Lehigh Press, Inc. for his contribution to this Q&A article. Brian was a speaker on overprinting foil at the recent FSEA National Convention held in October of 1995 in Chicago, IL.