# Print Quality Analysis of Stone Paper and Coated Sticker Paper Used in Screen Printing
## 1 Introduction
Since its invention, stone paper has become commercially available in the form of waterproof books, notebooks, and artist papers. Stone paper magazines, sketchbooks, and plain paper products are manufactured for office printing, writing, artwork, and other practical uses. Notebooks made from stone paper are increasingly being purchased from regular bookstores and stationery suppliers [21]. Similarly, there are printability studies on bio-composite layers produced using polyester resin and epoxy [22; 23]. Coated sticker paper was selected in this study since it is a cellulose-based paper frequently preferred in the printing industry. It was also used to compare the behavior of stone paper and coated sticker paper in screen printing. Screen printing (formerly silk printing) is a stencil process in which ink is transferred to the substrate through a stencil supported by a thin fabric mesh of silk, synthetic fibers, or metal threads stretched tightly over a frame. Pores of silk are occluded in non-image areas and left open in the image area. This image carrier is a so-called mesh. The frame is fed with ink flowing onto the mesh/screen during printing. It is then drawn with a squeege, which forces the ink through the open pores of the screen. Meanwhile, the substrate is fixed under the screen. It comes into contact with the screen, and the ink is transferred [24]. Screen printing is preferred since a thick layer of ink can be transferred onto a substrate (Figure 1). Figure 1: Diagram of screen printing workflow [25]. This feature easily distinguishes screen printing from the other printing techniques; in general, the ink thickness for screen printing is around 20-100 \(\upmu\)m, and for offset printing, it is typically around 0.5-2 \(\upmu\)m. The thickness of the stencil (the distance at which the stencil rests on the screen) designates the thickness of the ink layer [1]. The factors affecting screen printing quality and their optimization have been researched for several years. [PERSON] and [PERSON] conducted a study in 1971; they reported 50 different parameters that affect the quality of screen printing and optimized these parameters. They combined the results of the most critical parameters in 300 different ways [26]. For instance, the squeegee used in print is a parameter; however, changing the drawing pressure of the squeegee during printing or changing its hardness will cause a change in the ink to be transferred onto the substrate material [27; 28]. The mesh/screen is the most important factor affecting quality in screen printing since the mesh count determines the rate at which ink is transferred to the substrate. The mesh count and material used in screen printing may vary based on the desired amount of ink to be obtained, the desired characteristics of the image to be printed, and the substrate material to be used. The mesh count refers to the number of threads per centimeter (tpc). Various materials can be stretched over the frame to create the screen printing pattern. Materials such as silk, nylon, monofilament, and multifilament polyester, or metals, are widely used today. Screen printing screens can be produced in 10-200 tpc mesh counts [29]. Screens with a thread count of 200 tpc and above are used for surface printing when more precise patterns are required [3; 30]. The distance between the threads increases with decreasing mesh counts, so the amount of ink passing through increases. On the other hand, the amount of ink passing from the screen to the substrate decreases with increasing mesh counts, but more regular and controlled ink transfer is achieved. Generally, the mesh thread wire diameter decreases or increases proportionally to the mesh count. Wire mesh diameters also affect the amount of ink passing through the mesh [31]. It was indicated in previous studies that the mesh thread count and opening play a key role in determining the amount of ink passing to the substrate, and mesh thread opening is an essential factor in choosing mesh counts [30; 32].