Silk screen printing on packaging

Silk screen printing is a popular printing method, also known as stencil printing. It is used to apply images to various products. Any image on glass or plastic turns out bright, does not fade over time, and does not wear off. The technology for creating highly durable images is suitable for applying text or logos to packaging.

History of the silk screen printing method

The essence of the method, what silk screen printing is, is revealed in the name of the technology, which consists of two Greek words: seri (“silk”) and grafia (“writing, image”). Decorating with silk has been used since ancient times. One of the oldest methods of applying images appeared in primitive times in what is now Lebanon. The drawings in the caves of the Pyrenees were made using cut-out stencils, through which paint was blown onto stones through tubes.

The guardians of the silk screen printing method were the Phoenicians in the Middle East, who reproduced simple pictures using special matrices - stamps. A similar printing method was used in ancient China when the production of natural silk reached its peak. From East Asia, the technology spread to India, and around the 16th century, silk screen printing reached Europe, where it developed for several more centuries.

The method of applying images was actively introduced in European countries and the United States. In 1907, the process of manufacturing screen printing stencils was patented by the Englishman Samuel Simon. The new technique of printing through silk fabric developed rapidly, which made it possible to reduce the cost of prints. As a result, silk screen printing began to be widely used for commercial purposes. The development of industry made it possible to apply images to three-dimensional surfaces as well. In subsequent periods, the method was continuously improved in order to reduce technological limitations.

Advantages and disadvantages of the method

Advantages

The main feature of silk screen printing is the wide range of possibilities offered by this printing method:

• application of images to curved and textured surfaces, products of any size with minimal pressure on the base;
• a wide selection of materials and colors. Pure tones are rich and saturated. It is possible to cover the surface with gloss, use scented varnishes, luminescent, fluorescent, metallic paints with a golden or silver effect. To give the image volume, foaming of the paint is allowed, which adds attractiveness to printed products;
• high image durability. Despite the shallow penetration of the paint into the structure of the base, the image does not fade in the sun and does not wear off if the care instructions are followed.
• Combination with various types of post-print image processing - varnishing, embossing, hot stamping.
• High-quality printing on low-permeability surfaces such as glass and plastic.
• Image durability on the surface and decorative effect thanks to the 10-12 micron ink layer thickness. Can be increased to 500 microns.
• The printing process does not require connection to electronic devices.

Disadvantages

The disadvantages of silk screen printing are, first and foremost, complex and time-consuming pre-press preparation, reproduction of vector images with clear contours that do not lose quality when scaled, and the inability to create color transitions. Changes to the design require the printing form to be redone.

The need for careful preparation for the work process and labor costs determine the use of the silk screen printing method in the production of goods for wholesale. The manufacture of individual items is not practical.

Screen printing technology

Silk screen printing is a type of screen printing where, instead of a stencil, a form with a stretched dense mesh is used. As a rule, it is made of metal or synthetic threads—nylon, polyester. The varieties differ in the number of threads per cubic centimeter, with a thickness ranging from 40 to 500 micrometers. The required mesh form is selected for a specific job. If multicolor printing is planned, a separate template is required for each shade.

To create a pattern on the mesh, a layer of polymer light-sensitive material, or photoresist, is first applied. The areas corresponding to the future image are covered. After exposure to ultraviolet light, the layer polymerizes, becomes insoluble in water, and the rest is easily washed off with water. As a result, printed elements remain that are capable of passing ink after the photoresist is removed from them. This is how a unique stencil is formed.

In the process of printing using silk-screen technology, ink is applied to the screen with photoresist, which is spread over the entire length of the form with a special tool - a squeegee, similar to a soft spatula. Viscous solvent or plastisol inks are used, which produce a relief layer. The ink passes through the cells in areas where there is no polymer light-sensitive material. In this way, the print is transferred to the base. Next, the product with the image must be dried.

What is needed for a high-quality image

To obtain a bright and even image, special paints with thixotropic characteristics are used. Depending on the force of impact, the paint changes its consistency. The dyes contain catalysts, pigments, solvents, humectants, and binding resins.

To get a high-quality image, you need to do the following:

• The paint must be distributed evenly over the surface. The thickness of the dye layer depends on the smoothness and stiffness of the squeegee, its angle of inclination, and the pressure applied. The optimal angle for printing is 75°. If it is less, there will be excess paint on the surface; if it is more, it will be sparse.
• You can achieve an even application by passing a rubber squeegee first in one direction, then in the opposite direction.
• The viscosity of the paint must be controlled. Liquid ink leads to blurred contours, while thick ink leads to gaps.
• It is important to choose the right screen parameters. The screen is selected for specific tasks, taking into account the number of threads per cubic centimeter in the range from 10 to 200. Incorrect selection leads to an image with uneven edges and other defects. The thickness of the threads and the distance between them determine the density of the applied paint layer.

An incorrect approach and violation of the silk-screen printing technology leads to a “sticking effect” when the substrate does not separate from the screen stencil.

Types of substrates suitable for silk screen printing

Silk screen printing is suitable for natural and synthetic materials. The printing technology can be used for:

• glass products;
• plastic products;
• textiles, etc.

Silk screen printing on bottles, jars, caps, and lids allows you to create a variety of colorful designs with rich colors. Such design solutions attract the attention of buyers and make the product memorable.

Silk screen printing can include inscriptions with information about the product and the manufacturer. For example, barcodes, logos, composition, methods of use, and other useful information for the consumer. A unique stencil is made for each product.

Why is silk screen printing more expensive?

Silk screen printing technology is not considered budget-friendly. Compared to other printing methods, it is more expensive to use. Silk screen printing is not used for single items. Silk screen printing is used for printing requests where premium-class products need to be identified. There are no ready-made diagrams, templates, or other preparations for fulfilling an order.

Preparation for silk screen printing involves several stages and compliance with a number of conditions. The final cost is influenced by the characteristics of the technological process:

• the manufacture of unique stencils for applying each shade of color printing;
• the use of special paint with thixotropic properties, which contains more pigment and binders to obtain a durable image;
• the use of manual labor, which is always more expensive than a mechanized process.

This service must be ordered from professionals who will create a unique design, taking into account parameters, surface texture, image format, paint characteristics, and other nuances. A professional approach will ensure high-quality printing and the implementation of original projects.