Silk screen printing is one of the most commonly used printing techniques. The printing on the packaging is achieved by forcing a thick ink-paste (5) evenly through the mesh of the screen (3) with a special plastic blade (1). A fine mesh material is stretched over a wooden or metal frame (2) to form the print screen. The screen can be of silk, synthetic or metal that is coated with special polymer. The required text or logo is transferred to the screen from a negative. The unexposed areas (4) remain soft and washable, while the exposed areas harden out to form an ink impermeable coating on the screen. During the printing process, the ink is stencilled through these soft "open" parts of the screen onto the packaging product. Finally the printed articles (6) are run through a heated chamber for drying. In the case of Polyethylene (PE) products, these must always be prewarmed by "flaming" the articles, so as to achieve good print adhesion.
Silk screen printing offers many advantages, like brilliant colors, long term storage period, low cost, ease of use, etc. However, high ink density is the most significant one. Compared with other printing techniques, it allows a greater thickness of the ink to be applied to the stock. In addition, silk screen printing can be used to print on most surfaces, whether a flat, spherical or concave/convex surface. In addition, it is suitable for both soft and hard products.