Research On Calculation And Utilization Of Spot-color Ink For Offset Printing

At present,various printing companies generally have a surplus of spot-color ink in the offset printing process,resulting in a lot of waste.In view of this situation,this paper studies and explores the two aspects of ink calculation and residual ink utilization.This paper establishes calculation model for the spot-color ink.Firstly,by analyzing the influence of the solid density on the relative contrast and the influence of the ink thickness on the solid density for the primary ink,this paper establishes the solid density-relative contrast model and the ink thickness-solid density model to obtain database of the optimal solid density and the optimal ink thickness.Secondly,the spotcolor ink is blended with the primary color ink in different proportions and its the optimal solid density and the optimal ink thickness can be obtained.By establishing the optimal ink thickness model of the spot-color ink and the primary color ink,the calculation model of total amount of the spot-color ink is obtained.Finally,in order to verify the accuracy of the model,this paper selects four representative ink to design experiments.The result shows that the total amount of ink calculated by the ink calculation model for the four spot-color inks is close to the actual ink amount,and the remaining ink volume ratio is less than 10%.At the same time,in order to verify the practicability of the model,this paper compares the size of the ink value obtained by the model and manual experience.The result shows that the remaining ink volume ratio by manual experience is 44%,and the remaining ink volume ratio by the model is 8.8%.Therefore,the ink calculation model can accurately calculate the ink volume,effectively reduce the residual ink,and save the enterprise cost.This paper also establishes utilization model for the spot-color ink.Firstly,the IGT printability tester is used to print residual ink splines of different concentration gradients.The spectral information of the splines is collected by spectrophotometer to establish a residual ink database.Secondly,the optimal residual ink is obtained by using the selection method of minimum color aberration.The optimal residual ink is added to the computer color matching model to obtain a predicted formula.Finally,the color aberration between the standard color and the predicted color of the spot-color orange is 0.63,and the color aberration between the standard color and the predicted color of the spot-color brown is 0.78.Since the color aberration values are relatively small and meet the color aberration requirements allowed by the printing,the re-color matching of the residual ink is realized under the premise of accurate color.