Gravure Ink Viscosity: Viscosity Control Features that Converters are Now Demanding
Shorter production runs, OEM press automation, and competitive pressures are daily challenges for gravure. Press rooms are now looking to shrink make-ready time and gain productivity advantages through improved viscosity control.
All press equipment, including viscosity control systems, need to be much more reliable, require significantly less maintenance, enable shorter make-ready times, and be able to operate in a world where pressman skills are decreasing.
Complexity and its impact on pressroom operations is evident in Exhibit 1 below. This exhibit shows that the typical pressroom operates only slightly more than 54% of the time, with a whole series of activities taking up the rest. Two of the non-productive categories are make-ready, which uses 20% of the total press time, and color-match which makes up 8%. The viscosity control system influences the amount of time required by both of these.
This system needs to help converters reduce this non-productive time and improve run quality and productivity, to be part of the solution instead of the problem.
Factors Influencing Viscosity Control Improvements
A number of factors influence viscosity control Several are particularly important to consider. These include ink consistency, temperature, and color consistency.
Ink Consistency: First, let’s discuss the relation between viscosity and ink consistency. Viscosity relates directly to the amount of solids in the ink or coating and ties directly to the converter’s costs and perceived quality. This can be clearly seen in this chart (Exhibit 2) which shows the results of a 12 week test by one converter. It involved two sequential periods in which the converter controlled viscosity differently but kept everything else constant in the process, and recorded the results of coat weight tests. In the first six weeks the traditional manual method of viscosity control was used, while during the second six weeks an in-line automated viscosity control from Cambridge Viscosity was employed.