Ink Performance and Economics

Fact 1: Ink is a Critical Component. The ink utilized in digital equipment is an extremely critical component in the production of high quality graphic output. This is especially true in UV-curable digital equipment since ink density, viscosity and curing speed must be optimized for the specific print head and printer design. If ink performance is compromised, print quality will suffer and result in premature print head failure. Ultimately, it is the performance of the ink through the printer onto the specific substrate that determines the quality of the printed graphic.

Fact 2: Understanding the True Cost of Ink. The correct economic measurement of ink cost is not the cost per liter of the ink rather it is the applied cost of ink on the graphics. The applied cost of ink can be calculated as follows:

Applied Cost = Yield of ink per liter + non-print operations (purging)

  • The lower cost per liter of ink does not necessarily equate into a lower applied cost of ink. This is because the yield or mileage of the ink varies based upon ink formulation and the efficiency of the overall printer design and system. Ink mileage can also be affected by the RIP software, the color management tools employed (such as profiles) and how the art file itself is configured.
  • The cost of ink consumed in non-print operations can increase the overall applied cost of ink by as much as 50%. This is due to the fact that routine purging of print heads is a standard maintenance procedure on many, but not all, UV digital printers. On some printers purging is done to maintain the heads in a useable condition throughout the production shift. However, the ink purged through the heads is NOT printed on any graphic but goes directly into a waste container. In essence, the end user will pay for this ink twice – once as it comes in the plant and again as it is removed as waste.

Fact 3: Affect on Achievable Color Gamut. The achievable color gamut off the printer is significantly impacted by the ink formulation, specifically the pigments used and how these pigments are balanced in the ink set. If the pigments in the ink set are not balanced, the resulting color gamut will likely be smaller. An improperly balanced ink set may result in prints that are “dirtier” and farther from the desired color when ink saturations are increased.

Fact 4: The Impact of Ink Saturation. Most UV digital equipment permits the ink saturation (or amount of ink printed) to be varied. This may alter the achievable color gamut but it does so at a cost. The higher the ink saturation, the higher the applied cost of ink. In addition, if the ink is not properly formulated, you may still not achieve the desired color or cleanliness you seek.

Fact 5: True Ink Costs are Difficult to Measure. Most UV digital equipment does not provide a method or system to calculate the amount of ink printed on a graphic or the amount of ink purged through the heads on any sort of time scale, be it daily, weekly or monthly.

ROI Demonstration Proof Point:
Given the critical nature of the ink, how do you evaluate it in the purchase decision process? Is evaluating colors on prints and adhesion to critical materials enough? As we have shown, the answer is absolutely not. In order to fully assess the ink performance and economics on each digital printer you are considering, you need to evaluate and quantify the following:

  • Assess the ink adhesion to your critical materials at all print modes and speeds.
  • Determine the end user requirements you will need to meet for the potential applications you plan to do on the equipment. This should include: weatherability and light fastness, flexibility, chemical resistance, finishing operations of the graphics, compatibility with laminates or overprint clears, and overall appearance of the graphics.
  • Ensure that you have real measurements of the applied cost of the ink for various types of graphics.
  • Determine the maintenance procedures utilized for the print heads and the frequency on which they are performed and the resulting cost of any consumables used in the procedure (such as ink).
  • Determine the color gamut and saturation levels you will need to meet your customer requirements and the resulting impact on the yield and applied cost of ink.
  • Measure the color gamut of the printer and the ink set at the various ink saturation levels on that equipment and compare it to the same information for the other equipment you are considering.
  • If measurements to determine the applied cost of the ink are not available on the equipment, talk to current owners of the equipment and ask them these three questions: 1) How much ink do you consume per month (liters)? 2) How much work do you produce off the equipment per month (square feet)? 3) How much ink or waste material do you dispose of each month off this equipment and what costs do you incur as a result?

NOTE: It is recommended you contact and compile the above information from 3 to 4 companies – you will have a very good assessment of the applied cost of the ink on a per square foot basis on the equipment you are reviewing.