How to evaluate quality of printing by using water based flexo ink? Printing by using water based flexo ink is easly to evaluate quality of printing if you know well the characteristic of water based flexo ink which you selected you use in printing The main idea The main idea of Water based flexo inkprinting technology depending on transferring the ink from the machine parts, Anilox with doctor blade to substrate with image of printing, so the formulation of water based ink should has some component to have good Image also Anilox roller cells number is important in printing process. First, you should select suitable substrate suitable for the application which you will use as end product, like Kraft, white or brown, tissue, coated or uncoated paper also absorption of substrate must be considered as important factor when you select the suitable type of water based flexo ink and anilox no, also is very important to have good printed substrate Kraft paper is the main type of substrate which use for producing this type of boxes, thickness and weight also absorption are main factors which detect the type and quality of Kraft substrate. Viscosity of water based flexo ink is very important to have good performance on printing machine which is controlled by ink manufacturer easily by using suitable material in formulation to match with type of printing machine and it is easily measuring by lab equipment by seconds or centipoise sometime the ink needs to dilute, after dilute water based ink by water sometimes causes foam that why users of water based flexo ink complain from that foam but this type of problem is easy to solve by adding some of Antifoam additive ,some drops of antifoam can kill this foam in seconds specially during printing process. due to flexo water based ink is water soluble user can dilute water based ink by normal water.
How can I achieve optimum flexo printing quality? For achieving optimum flexo printing quality, there are major steps that should be followed. pH control: Proper pH is critical to achieving sharp and defined printing image. Ph that is not properly adjusting from color to color on the printing machine will cause a number of printing defects. pH is acidity, neutrality or alkalinity of a liquid ranging from 1 to 14 on a pH meter. Below 7 is acid and above 7 is alkaline and 7 is neutral. Flexographic ink should be on the alkaline side of the scale, so pH should never be below 8 or higher than 9.5 in flexo ink pH reading should be taken and adjustment made when viscosity readings and adjustment are made. pH adjuster, supplied by the same ink supplier. The challenge is in keeping pH up, not down, and to achieve the stepping of pH, it is important to use measuring cup amounts for this purpose, hot humid condition and evaporation accelerate downward movement in pH. Viscosity control: Ink viscosity determine the rate of flow and is measured in seconds by using a No.2 zahn cup, the device that allow liquid to through an opening at the bottom of the cup, and which is the adopted instrument of the corrugated board industry. The proper viscosity is that which achieve suitable coverage and color density matching a costumer color sample. Two vehicles are used to reduce the viscosity, water and extender varnish. As with pH adjuster, a measuring cup of either water to extender varnish should be used to avoid reducing viscosity to a point where desire coverage and density are no longer achieved. Often it is better to use extender varnish that has the same properties as ink, except pigment. This vehicle will have less effect in reducing the solid content of the ink. In the next article we will talk about setting impression and cleaning printing plate.