Silk-screen printing (screen printing). Screen printing What is screen printing

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Screen printing- this is a printing technology in which ink penetrates onto the media through a special form with a finely porous mesh of nylon, polyester or metal stretched over it with a thread frequency of 4 to 200 units per centimeter and a thickness of 18 to 200 microns.

Screen printing is perhaps the most ancient printing method that has survived to this day and has not lost its relevance. It is often referred to as screen printing, but silk screen printing is only one type of screen printing.

Work on a sheet stencil machine

Screen printing compares favorably with other printing technologies:

• firstly, a wide variety of materials are suitable for stencil machines, ranging from sheet and roll paper to fabric, wood, leather, plastic, glass, ceramics and metal;
• secondly, stencil machines are unpretentious to paints, they are able to work on metallized, heat-sensitive, electrically conductive, foaming, reflective, fluorescent and many other types of paints;
• thirdly, in the printing process, you can use all sorts of effects, such as sequins (glitters), 3D printing, rubber or velvet imitation;
• fourthly, stencil machines create images from layers of paint of different thicknesses, providing a slight visual 3D effect.

Stenciled products can be found in most sectors of the national economy. Screen printing is used to design various types of business products, promotional items, home and work wear, sporting goods, home goods, art products, etc.

Screen printing occupies only a small segment of the printing market, but at the same time a huge variety of applications is available to it.

Distribution of screen products by market segments served by screen printing

In the electronics industry, screen printing is used in the production of membrane switches, soldering stencils and circuit boards. Printing on clothing and fabrics includes the decoration of finished clothing and materials, it covers the areas of product identification, ceramic production, jewelry, etc. Printing on cardboard displays is offered for the design of retail outlets and the manufacture of various signs.

In outdoor advertising, this method is used for various purposes, ranging from quick marking to the design of billboards. Artistic screen printing allows you to make art reproductions and a variety of printed products: calendars, posters, postcards, diplomas, etc.

Screen products

The list of materials that can be printed or decorated with screen printing is truly endless.

For screen printing, both conventional installations and devices are used, as well as large devices for work on an industrial scale.

Machines for roll and sheet screen printing

The screen printing machine can consist of one section, or it can be a production line of 16 sections. Accordingly, the staff of the printing house may consist of one person carrying out the admission of one type of product, or hundreds of people producing different types of stencil products.

With the help of screen printing, it is possible to produce both huge images intended for decorating large-sized objects (trucks, airplanes, shop windows), as well as tiny drawings and diagrams no larger than 0.2 mm (for example, circuit boards for microelectronic devices).

Screen printing development trends include the following:

• Increasingly, the method of direct exposure of forms from a computer to a printed grid is used, especially for large volumes of printing in sections with rotary devices of a stencil machine;
• An innovative method of filmless production of printing plates using inkjet printheads is proposed. This direction is very promising when sealing large format materials. It is currently little used.
• New types of high-strength materials are being developed, as well as ultra-thin meshes and wires for screen molds with a large number and density of cells.
• We should expect the appearance of printers with an extended color layout for printing on sheet materials.

Screen printing is not fast enough, so in the near future it will be necessary to develop new quick-drying types of inks that allow you to increase the printing speed.

Silkscreen technology. The information below should not be considered as a direct guide to action. The information is an overview, the main task is to convey a certain minimum to those who have no idea what silkscreen / screen printing is.

Since there are many key points in the technological chain, we strongly recommend that you carefully study the literature on this topic and consult with suppliers of equipment and materials.

Silkscreen technology. Screen printing plate

Silk-screen printing technology implies, first of all, the production of a screen printing plate. For manufacturing, as a rule, aluminum rigid frames are used.

Roller frames and wooden frames are used much less frequently. The first due to the relative high cost, and the second, wooden frames - the most economical option, but not the best.

Using tensioners, a special mesh made of polyester or stainless steel is stretched, then the mesh in the stretched state is glued to the frame.

On the video: the process of tensioning the mesh on the high-end tensioner SAATI TOP12 is shown.

There are also simpler and cheaper mechanical tensioners. Some printers use roller frames as tensioners, although they are not designed for this. If they are used for their intended purpose, then there is no need for a separate tensioner and glue.

On the video: the process of tensioning the mesh on the roller frame

After the mesh is stretched and glued to the frame, using substances that fall under the general name "chemistry", the mesh is roughened and degreased.

We apply a photosensitive layer - these are photographic emulsions or capillary films.

A photographic emulsion is poured into a squeegee cuvette and applied on both sides of the grid.

In the video: applying the emulsion with a squeegee-ditch.

In the photo: drying cabinet for screen printing forms

With a large load of the stencil section, drying cabinets are used, in which several racks are placed.

The next stage of screen printing (silk-screen printing) technology is exposure. Exposure from color-separated films takes place in exposure devices with a vacuum clamp, as a rule, by contact.

In the photo: exposure device with a point light source

After exposure - development. Unexposed areas of the photolayer dissolve in water, illuminated areas remain on the grid. Development takes place on stands that have a backlight and do not allow splashing.

On the video: the process of preparing the grid before applying the emulsion, applying the emulsion, drying, exposure and development is shown.

The screen printing form is ready. The number of printing plates = the number of films = the number of colors that the design will be printed with. It should be noted that in most cases, the stencil can be removed from the grid and the photo layer applied again - i.e. make a new stencil (a process called "regeneration").

In the photo: this is what the stencil looks like when enlarged

Due to the characteristics of the equipment used, printing is divided into textile and graphic.

Silkscreen technology. Textile screen printing

Printing takes place on rotary machines. Printing plates are attached to the printheads, and T-shirts are put on the tables. The paint is pressed through the stencil with a squeegee. On manual machines, we print the first color on all T-shirts put on the tables, then the second color, etc. On automatic machines, printing occurs simultaneously on all print heads.

In the photo: a manual carousel machine for printing on T-shirts

When really good productivity is required, automatic textile carousels are used.

In the photo: automatic carousel machine for printing on T-shirts

In the direction of rotation of the tables, an intermediate dryer is installed - “drying”. On a manual press, it is placed in such a way as to dry the ink on one table while the printer prints on another. It is used when they do not print "wet-on-wet", that is, almost always. On an automatic machine, it is usually installed instead of the print head.

In the photo: intermediate dryers - "dryers" are used for multi-color printing

After the last color has been printed, the T-shirt is removed from the table and passed through a tunnel conveyor dryer for final drying. If performance is not needed, then an intermediate dryer can be used for final drying (plus: noticeable cost savings, minus: significant loss of performance - several times).

Silkscreen technology. Graphic screen printing

The classic version is a machine with one printing plate and a table that provides vacuum clamping of the product / distal materials. Multi-color printing is carried out sequentially: we print the first color on a certain run, dry it, change the printing form, print the next color, etc.

Semi Automatic Screen Printing Machine

Depending on the paints used, different types of dryers are used. UV dryers are used for drying paints, varnishes and other materials with UV curing.

Conveyor UV Dryer

IR conveyor dryer with air circulation in the tunnel - a high-performance alternative to the pile dryer (pictured: Turbo JetStar dryer)

Stalk dryer - an economical option for working with solvent paints

Instead of a conclusion

Each type of equipment listed above has different options both in design features and characteristics, and in price. Therefore, first of all, you need to decide on the tasks. At a minimum, this is:

Type of printing (textile or graphic)
Maximum print size
Maximum number of colors/paints
Maximum productivity (e.g. impressions/hour, shirts/shift, etc.)
Is full color printing planned?

For more information, see the section, the FAQ section, and other sections of our site.

Screen printing or silk screen printing at home is a method of applying a pattern to different surfaces by forcing paint through a special mesh. The technology provides for the transfer of images to fabrics, stationery, dishes, plastic bags, etc. No complicated manipulations and expensive equipment are needed.

Making silkscreen at home is beneficial because it:

• handmade (always relevant and valuable);
• no restrictions on the types of images;
• brightness and brilliance of the picture;
• a wide choice of materials - paper, plastic, fabric;
• low cost;
• simplicity of technology;
• compactness - no need for a separate room and bulky equipment.

Screen printing devices take up minimal space

Screen printing mesh

The quality of silk-screen printing depends on the printed form, namely, on its base (grid). She happens:

• Polyester. It is used when printing with water, plastisol, solvent paints. The type of weaving is also different: canvas (1:1 - one thread to another) and twill (2:1 or 2:2). The former are used more often.
• Steel. It is used exclusively when working with thermoplastic paints.

Nets are available in white and dyed yellow. The latter provide maximum clarity of the picture with detailed detail.

White and yellow nets for screen printing

Notice the linework. It is on the label. For example, the marking on the grid "No. 120-34" means that the size of the lineature is 120 lines per centimeter, and 34 is the diameter of the thread. The higher the first parameter, the thinner the mesh.

Mesh fabric is divided into categories depending on the thickness of the threads. Each category is indicated by its own letter (it stands next to the number: S, M, T, HD - from light to the most severe). A fabric with a thick thread is stronger, it is pulled with great effort. The thickness of the thread affects how much paint will pass through the mesh.

When working with a thick canvas, the edges of the pattern lose their clarity. Chips may appear. Choose thin grids for small images.

Screen printing frame

Screen frames are used not only in printing houses, but also at home. They are subject to the following requirements:

• reuse - in order to reduce the cost of printing;
• chemical resistance - when washing and applying a photosensitive layer and paint, contact with the frame is inevitable;
• rigidity - the frames are made of a material that is rigid, resistant to twisting and bending deformation;
• light weight - the frame should be light, mobile.

The simplest stencil frames for screen printing are made by hand from straight-grained wood. They are light, cheap, but sensitive to moisture.

The alternative is aluminum. It is inexpensive, lightweight, allows you to achieve the required tension. The frame made of aluminum is not affected by the chemicals used in screen printing, is suitable for repeated use, and retains its geometry.

Ready-to-use wooden frames

Stencil without exposure and emulsion

Another way to make stencils for screen printing is using a heat press. It was developed by the Americans. You will need a laser printer. Start by printing your desired image on plain xerox or offset paper. Print in black and white.

Now lay the printout face down on the prepared transfer paper and send it to the heat press. It will take 20 sec. at a temperature of 110 ०С - the image from the printout will be transferred to transfer paper.

It must be placed face down on the frame and put back into the heat press. This step lasts half a minute. Working temperature - 180 ०С. The stencil is ready.

This is what a heat press looks like

Drawing a pattern on fabric

You will need a mesh, frame and paint. In the presence of artistic talent, the drawing is created with a brush, in the absence of - on a computer. For beginners in screen printing, we recommend starting with large solid images, that is, without small details and complex geometry.

Step 1. Image selection. The screen printing pattern at home can be anything: a logo, a picture, an inscription. It is drawn or found on the Internet and then printed on a printer.

Step 2 You can take a finished frame with a mesh or pull it on yourself, securing the edges with a construction stapler. It is necessary to additionally glue them with paper tape or electrical tape - the paint will not spread.

Step 3 The frame is covered with photographic emulsion. This is a light sensitive compound - a dark room is required. It is applied from top to bottom, carefully working through each area. The frame is allowed to dry in a horizontal position - approximately 1-3 hours (the time depends on the thickness of the layer).

Step 4 The dried mesh is covered with a piece of dark fabric. This is light protection. The frame with the grid is placed on a stand, facing towards the light source.

Step 5 The next stage of screen printing at home is the preparation of a sample for printing. They take the image as they need to be transferred to the product, turn it over and place it on the frame.

Step 6 Now you need transparent glass - with its help, the pattern is pressed against the grid. You can turn on the light. For a 60x60 cm grid, it will take an average of 35 minutes with a 150 W lamp 45 cm away from the image. After that, a barely noticeable imprint appears on the stencil.

Step 7 The stencil pattern must be opaque. To verify this, look at it, aiming at a light source. If the rays penetrate the picture, the quality will be lame. You will need to print another copy and overlay the first one. Another option is to paint over the sample with a marker.

Step 8 Now you need to rinse the frame with warm water. As the emulsion is washed out, the print will become more and more pronounced - the stencil is ready.

Step 9 The prepared stencil is placed on the product. The frame with the mesh on the outside must be in contact with the work surface. If it is a fabric, for convenience, something solid and even is placed under the bottom.

Spread the paint on the stencil and evenly distribute it with a rubber scraper. The more you press on the scraper, the clearer the pattern will be. It should be borne in mind that after drying, the paint will acquire a darker shade.

Step 10 The finished product is dried. To fix the image, the fabric is ironed.

The paint must not destroy the stencil material. Choose one that dries no faster than the printing process.

The picture is bright and full color.

The process of silk-screen printing on fabric is shown in the video:

Results

• Silk-screen printing on fabric is possible at home: it is simple and low-cost.
• The technology is used to create unique T-shirts, souvenirs, pens, pillows, mugs.
• You can create a stencil with your own hands, what you need: fabric, mesh, frame and paint.
• Modern technologies allow you to create stencils without emulsion and exposure.

Basic components of screen printing.

Stencil. In screen printing, the form is - a stencil, which is a mesh on which the mesh is stretched. A photographic emulsion is applied. A positive (photo output) is superimposed on the photographic emulsion. With the help of an ultraviolet light source, the emulsion is illuminated. Those parts of the photographic emulsion where the light hit harden, and where it didn’t hit, they are washed out. In the process of printing, ink is forced onto the product through the sections of the grid free from photographic emulsion, as a result of which a printed image is obtained.

A squeegee is a device that is a rubber spatula with which the paint is pressed through the stencil mesh.

Forrakel is a device that is a metal spatula with which the ink returns to the beginning of the print.

Screen printing theory.

Basic conditions for quality printing.

1. Ensure contact between the emulsion layer on the printed side and the surface of the printed product along the entire length.

To ensure this condition, the following parameters are met. Squeegee pressure force. The magnitude of this force must be sufficient to ensure good contact between the grid emulsion and the printed material along the line of contact. The force is calculated per 1 cm of doctor blade, therefore, the longer the doctor blade, the more force must be applied to ensure good contact. The greater the squeegee pressure, the better the contact, but the higher the wear of the mesh and squeegee blade. Excessive pressure can cause the doctor blade to flex a lot, resulting in a reduction in print angle and an increase in ink dosage. Many printers mistakenly believe that the harder you press, the better the ink will come out.

To obtain optimal contact along the line of contact of the squeegee with the printed surface, the pressure force should be 10-15% more than the force that is sufficient to contact the table.

2. Ensure uniform dosing of paint. Forcing the required amount of ink through the stencil screen during printing (moving the squeegee) over the entire area.

Printing angle (the angle between the colorful plane of the squeegee and the grid). Changing this angle changes the amount of paint pushed through the mesh. The smaller the print angle, the more ink can be pushed through the mesh. With a very small printing angle, an overdose of ink occurs, which can cause the print to float LUBRICATE FORWARD. With a large one, on the contrary, the fill will not be dense enough. At an angle greater than 90°, the amount of paint pushed through the mesh is theoretically equal to zero. The optimal printing angle is 75°.

Print speed. We must try to keep the maximum print speed to ensure the performance of the printing area. The speed is affected by the viscosity of the paint. The higher the viscosity, the lower the printing speed and the higher the likelihood of the squeegee floating on the ink. Therefore, you need to set more squeegee pressure.

3. Ensure that the sieve is separated from the paint immediately after the squeegee passes.

Print gap (distance between the grid and the printed material). When this distance changes, the force of separation of the grid from the printed material changes. The larger the printing gap, the smaller the separation angle and the greater the force that tears the mesh from the ink. But as the print gap increases, the print angle also decreases.

Tear-off angle (the angle between the mesh and the printed material behind the squeegee). When this angle is changed, the force of separation of the grid from the printed material changes. The smaller the separation angle, the greater the force that tears the mesh from the paint. At an angle of 180°, the tearing force is zero. In addition to the angle, the tearing force depends on the tension force of the mesh on the frame. Therefore, the more the mesh is stretched, the greater the force at the same separation angles.

Separation zone (distance between the line of contact of the squeegee with the sieve and the line of separation of the mesh from the printed material). The size of the separation zone directly depends on the magnitude of the separation force. The larger the printing gap, the smaller the tear-off angle and the greater the force that tears the mesh from the ink, which means that the tear-off zone will decrease, which reduces the likelihood of smearing the print LUBRICATE BACK.

Grid tear force. The magnitude of this force must be sufficient to ensure a quick separation of the grid after passing the squeegee. As mentioned above, the tearing force directly depends on the mesh tension force. The greater the tension force, the greater the tearing force at large tearing angles, which means that you can set a smaller printing gap.

4. Ensure uniform spraying of the paint.

The return of the ink occurs with the help of a squeegee (in manual printing, its function is performed by a squeegee). In the forrakel, as well as in the squeegee, there is an angle between the sieve and the colorful plane. The size of this angle determines how much to push the forrakel of the paint into the sieve when it returns to its original position.

There are 2 types of forrakels: Spatulas, (Angle up to 90 degrees) they are designed for printing with viscous inks and press more ink into the sieve and Scoops. These squeegees have an angle greater than 90 degrees and are designed for liquid (low viscosity) inks such as UV and UV varnish. When using spatulas, the paint is transferred to its initial position, as it were.

Irrigation must be adjusted so that the ink evenly covers the surface of the printed image, but does not leak onto the printed side. If the ink does not cover the printed image, there may be a misprint or an uneven layer on the print. When ink flows onto the printed surface (liquid inks), it is smeared, usually forward.

5. Avoid smearing when printing.

When printing images, a vertical force is applied to the stencil screen through the squeegee (to ensure contact between the printed surface of the screen and the printed substrate) and a horizontal force to move the squeegee. When the squeegee moves, a friction force arises between the squeegee and the mesh, and since any sieve tends to stretch, the image on the mesh under the influence of force shifts in the direction of the squeegee movement. After the squeegee makes a printing stroke, forces are removed from it, which leads to the disappearance of the friction force and the grid returns to its original position. In this case, the lubrication of the colorful edge occurs. The more viscous the paint, the greater the pressure force on the squeegee, the weaker the tension of the sieve and the greater the coefficient of stretching of the mesh, the greater the amount of smear.

To reduce smearing:

It is necessary to reduce the pressure of the squeegee,

If possible, reduce the viscosity of the paint.

Types of screen printing.

1. The initial state.

a. The stencil is up.

b.

c.

2.

a.

b.

c.

3.

a. The squeegee moves to the end of the image.

b.

c.

4. Raising the squeegee and stencil.

a. The squeegee rises from the grid.

b.

5. Lowering the forrakel.

a.

6.

a.

b.

c. Printing completed.

As a result, we see how the paint is pressed through the mesh onto a flat product with the help of a squeegee.

Disadvantages:

Impossibility of printing on a curved surface.

Slow print speed compared to offset printing.

Large amount of paint.

Advantages:

Ability to print very large formats at low cost.

High covering power of a paint layer.

Printable products - this method can be printed on almost any product that has a flat shape. Textile products (t-shirts, sweatshirts, windbreakers, jackets, overalls, bathrobes). Sheet material (paper, cardboard, self-adhesive, folders, business cards, envelopes, letterheads, posters, boxes, plastic sheet - plates, light boxes, sheet metal - signs, signs, panels, sheet glass - stained-glass windows, light boxes, furniture doors, laminated Chipboard - furniture doors, banner fabric - flags, streamers, posters).

The basic principle of circular printing is that during the printing process, the product rolls along the stencil, and the squeegee pushes the paint onto it.

1. The initial state.

a. The stencil is up.

b. The paint is thrown on the stencil mesh (there is paint in the mesh image).

c. The product is set for printing.

2. Lowering the stencil and squeegee.

a. The stencil is lowered to the product.

b. The squeegee is lowered to contact with the product.

c. The stencil mesh comes into contact with the product.

3. Moving the squeegee, pushing the paint onto the product.

a. The product roll on the stencil.

b. The paint is brought into contact with the product using a squeegee.

c. The stencil mesh comes into contact with the product.

d. Excess paint is removed from the mesh with a squeegee.

4. Raising the squeegee and stencil.

a. The squeegee rises from the grid.

b. The stencil rises from the product.

5. Lowering the forrakel.

a. Forrakel descends to contact with the grid.

6. Moving the forrakel to the beginning of the image.

a. Forrakel moves to the beginning of the image.

b. The paint is applied in an even layer to the open areas of the grid, filling them.

c. Printing completed.

Disadvantages:

The impossibility of printing on products with a large taper (more than 3-4 degrees).

Large amount of paint.

It is not possible to print mugs from handle to handle.

Advantages:

High hiding power.

Large print area compared to pad printing.

The possibility of applying a very high paint layer.

The possibility of reusable use of the stencil, the photomulsion can be washed off and a new image can be obtained again.

Low stencil production costs.

Printable products - this method can be printed on almost any product that has the shape of a cylinder with a small cone. To do this, the product must have sufficient rigidity. Dishes (mugs, glasses, glasses, bottles, ashtrays, thermoses). Packaging (jars, bottles, tubes, cardboard tubes, etc.).

Criteria of marriage in silk-screen printing and elimination of its causes.

The main parameters of the grid for screen printing.

1. Mesh fiber material.

Silk fiber. Now it is practically not used. the threads had a poor weave structure and low stability. But thanks to the first use of this material in the production of a stencil, the word silkscreen appeared.

Kapron. This material has high elasticity and low stability. It is used when printing on uneven surfaces and cylinders.

Polyamide monofilament. This material has high stability after the screen is stretched on the frame. Stability refers to the maintenance of a constant tension of the sieve during its operation. In 80% of all work performed, it finds application.

metallized fibre. It is used for printing on materials with high electrification. This material has high stability and good dissipation of static electricity.

Stainless steel. Metal meshes have very high stability and low stretch ratio. These properties are indispensable for printing high-precision boards and scales. High wear resistance of the material is used when printing on glass and ceramics. Also grids possess high removal of static electricity.

2. Types of mesh weaving.

Plain weave (PW). In this weave, the weft thread is woven through each warp thread. The basis is the threads located along the sieve roll.

Twill weave (TW). In this weave, the weft thread is intertwined through two warp threads.

Calendered sieve. To reduce the consumption of paints and reduce the paint layer (UV paints, gold-containing paints, etc.), the sieve is calendered. Calendering is the process of passing a mesh between two rolls, one of which is heated. Due to this, under the influence of temperature, the tops of the threads in the kink zone are flattened. This leads to a reduction in the thickness of the sieve H and ultimately to a reduction in paint consumption. The calendered sieve can be single sided or double sided. With single-sided calendering, ink consumption is reduced by up to 25%, and with double-sided calendering, up to 50%. The disadvantages of calendering are a decrease in the strength of the sieve and a decrease in the open surface area.

3. Stencil number.

The number (grid number) refers to the number of threads in 1 cm or 1 inch.

Mesh number 120 means that 120 threads are intertwined in 1 cm. The higher the grid number, the smaller cells it has. When printing rough images, where a high hiding power or thickness of the ink layer is required, lower sieve numbers should be used. The principle is as follows: the lower the grid number, the lower the resolution of the stencil and the thicker the paint layer, which means more paint consumption. The main criterion for choosing the grid number is the required thickness of the ink layer and the minimum thickness of the printed line (resolution). If the line thickness is close in size to the diameter of the thread, then such elements may simply not turn out already at the copying stage.

Screen dots during the manufacturing process can get on the threads and eventually fail, other screen dots, on the contrary, can get between the threads and simply be washed off during the development of the stencil with water. A thin line can be covered with a thread and have breaks in the form of a dotted line during printing, problems can also arise with sharp corners, in general it is almost impossible to push ink through a small hole, because. the contact area of ​​the ink with the emulsion is larger than with the printed material.

The thicker the paint layer is needed, the larger meshes should be used. At the same time, one should not forget that if there are thin elements in printed motifs, the use of large grids can lead to distortion or complete absence of these elements during printing (insufficient stencil resolution). In such cases, a compromise must be found between the thickness of the ink layer and the resolution of the stencil. In some cases, it is advisable to make two stencils for the same color, with different grid numbers. On one stencil with a low mesh number we will get high coverage, and on the other with a high mesh number we will get high resolution.

4. Series of stencil grids.

With the same mesh number, there may be a different thread diameter. There is a classification of meshes by series: S - extra light, T - light, TH - medium, H - heavy.

The difference between the series lies in the difference in thread diameters, the heavier the series, the larger the diameter of the thread. Heavy series have greater circulation resistance, but a less dense ink layer. This results in less opacity of prints.

5. Stencil color.

The mesh is available in two types: unpainted (white) and dyed (golden yellow, orange).

Colored grid is recommended for copying very thin lines and raster images. When a light flux hits the grid, most of it passes through it, a very small part is reflected, and a significant part is scattered. The scattered light flux contributes to the side illumination of thin parts, which can then be poorly washed. The dyed nets absorb the light falling on the threads and prevent the dispersion of the light flux, which ceases to illuminate the photographic emulsion, similarly to a red light that does not illuminate photographic paper. When using colored grids, it should be taken into account that the exposure time of the photographic emulsion increases, since the value of the useful light flux decreases due to the neutralization of its scattered part.

Ink composition for screen printing.

1. Coloring substances. Coloring agents are pigments or dyes. Dyes are soluble in the dye medium (solvent). During the dyeing process, they penetrate into the material and form a more or less strong bond with the fibers. The pigments are insoluble. In the paint, they are in the binder (linseed oil, nitrocellulose, etc.) and the properties of the paint depend more on the binder than on the pigment. The bond with the material to be painted is provided by a binder. Dyes are usually organic substances. Pigments are mostly fine dispersions of minerals, although they can be either organic or inorganic. The introduction of pigments into paints and varnishes is the main method for regulating the decorative properties of coatings - color and opacity (hiding power). A pigment imparts opacity to a pigmented material if its refractive index is higher than that of the binder. The greater the difference in the refractive indices of the pigment and the binder, the greater the hiding power of such a pigmented material. In addition, the shape of the pigment particles is important, for example, the lamellar shape of the pigment particles gives greater hiding power than needle or spherical.

2. Binder. The task of the binder is to stick the colorant to the surface of the printed product. Depending on the properties of the binder: adhesion of the ink to the printed material, drying methods, light fastness, ink layer height, gloss, abrasion resistance. The binder is usually based on a resin with a solvent, which is responsible for the consistency of the paint until it dries.

3. Additives. To improve the properties of the paint, there are various additives. The main types are listed below. Manufacturers may have other specialized additives.

Solvents - reduce the viscosity of the paint.

Retarders - reduce the viscosity of the paint and the speed of its drying.

Flow improvers - improve the flow of ink on the print, reduce the formation of small bubbles.

Thickeners - make the paint more viscous and thick.

Antistatic - improve the electrical conductivity of the paint, reduce the accumulation of static discharge, reduce static spatter.

Hardeners and catalysts - improve paint adhesion to difficult materials.

Matte additive - makes the paint more matte.

Pigments are coloring additives that increase the light intensity (saturation) of a color. Improper use of additives can impair the properties of the paint. Therefore, always strictly follow the recommendations of the paint manufacturer.

Basic paint parameters.

1. binder type. Printing, operational and adhesive properties of the ink depend on the type of binder.

2. Drying method (natural drying,. The speed of drying of the ink and its adhesion to the printed material depends on the drying method.

3. Hiding power (Transparent, translucent, semi-opaque, opaque, super opaque). The degree of hiding power shows how tightly the ink layer can hide the dark color of the printed material. If you print with transparent ink on black, the color of the ink will not be visible. If the paint is semi-opaque, then the color of the paint will be dirty due to the color of the substrate being translucent. Super opaque paints are able to cover the black color as tightly as possible.

4. Paint height (low, medium, high). The height of the ink indicates how thick the ink layer will remain after it has completely dried (Relief of the print).

5. Gloss level (paint super matte, matte, velvety matte, glossy, super glossy). Paint gloss refers to how much a paint layer can reflect or scatter light.

Variety of stencil inks.

There are four main types of inks used in screen printing: solvent, UV, and water-based. They differ in binding and drying method. Also, each type of paint has a large number of different series. Between themselves, the series differ in adhesive properties to various materials, elasticity, gloss, hiding power, thixotropy, etc.

IR - Infrared drying.

K - Convection drying.

UV - Ultraviolet drying.

* – Drying temperature depends on the paint series.

** - Used in two component series.

Screen printing is a method of reproducing an image using a stencil - a special printing plate through which printing ink penetrates the printed surface in those places that correspond to the printing elements.

Silk screen printing is a type of screen printing that uses special polyester, nylon or metal meshes of low thickness with a high filament frequency as the material for making the printing plate.
Silk screen printing took its name from the English name of the patent of the beginning of the last century for the screen printing process "Silk Screen Printing" - literally it can be translated as "printing with a silk screen" - silk screen printing. It is believed that this printing method originated far in antiquity, but the silk-screen printing technology acquired its modern look and widespread demand already in the middle of the 20th century.

Silkscreen is, in fact, an improved screen printing method, instead of the term "silk screen printing", a more accurate concept is used in printing - screen printing.

Screen printing or silk screen printing has a centuries-old history and is a method of reproducing texts, inscriptions and images, monochrome or color, using a screen printing plate through which ink penetrates the printed material.

Screen printing method

Screen printing method has higher artistic possibilities unlike other types of printing. In addition, the range of materials for silkscreen printing is almost limitless: paper, cardboard, fabrics, metals, glass, wood, synthetic film - printing on any surface. Silk-screen printing is applicable not only on flat surfaces, but also on three-dimensional, and even embossed ones. The thickness of the ink layer can vary from 10 to 100 microns, which ensures high image quality. Only in screen printing is it possible to use fluorescent and pearlescent inks to achieve various special effects.

• 1 - sieve cloth
• 2 - paint
• 3 - squeegee
• 4 - space element
• 5 - printing element
• 6 - colorful image
• 7 - printed material
• 8 - support table

A feature of the screen printing method is the structure of the printing form, its printing and space elements. The material or product on which the image needs to be applied is located on the side opposite to that from which the paint comes. The ink is fed through the printing elements of the form, which makes it possible to apply a layer of ink of different thicknesses. The flexibility of printing plates and the use of elastic squeegee allows you to repeat the shape of the printed products with minimal pressure.

Screen printing can be done on virtually any type of screen printing equipment, from the most primitive fixtures to fully automated machines capable of producing up to several hundred thousand copies. Screen printing can be done even at home.

Naturally, screen printing cannot compete with classic printing in publishing. And why? Silk-screen printing should be used where it is impossible to do without it. At present, small business is developing widely. And most of the small firms and private enterprises need only some types of printed products: an envelope, a sticker, a letterhead, an advertising booklet, business cards, etc. The circulation of an order can be only a few tens or hundreds of copies. And the simplicity of the technology for making screen printing plates makes the use of silk-screen printing even on manual machines quite cost-effective.

Our screen printing printing house "Print For You" offers screen printing services and other printing services at low prices with the ability to print any, including single, circulation, piece printing products, experimental and exhibition copies of products.

Currently, interest in screen printing has grown significantly in Russia. The fact is that the possibilities of classical printing methods are quite limited in terms of format, printed materials and the thickness of the ink layer. Screen printing has almost unlimited possibilities. In addition, silk screen printing is a printing technology that is relatively cheap and easy to produce printing plates. Now it is already possible to print in the semi-automatic way in 3x5m formats, and in the automatic way - 1.5x2.5m. Yes, and the thickness of the paint layer can be adjusted in a wide range. A significant drawback of screen printing, perhaps, is still low productivity.

Silkscreen printing differs from other printing methods in that the ink is forced through the cells of the grid on the printing elements, in which the grid is both the basis of the printing plate and the ink reservoir. Another difference is also the possibility of easy movement of the form and low pressure during the printing process. The quality of prints depends rather not on investment, but on the skill of the performer.

Today, a wide range of screen printing equipment of various degrees of automation and specifics is presented on the world market, which is an undoubted advantage of screen printing, because enterprises can choose what suits them according to the technology and available means. For example, large enterprises will require the use of automated equipment, while small ones will use manual or semi-automatic machines.

Screen printing can be used not only in publishing, but also in the production of special products, such as industrial silk-screen printing products. The screen printing method is applicable for printing on glass, plastic, porcelain, various types of packaging, CDs, volumetric objects of various configurations, as well as for varnishing any type of product.

Screen printing with appropriate inks can be carried out on almost any material: paper, plastic, PVC, glass, ceramics, metals, fabrics, leather, wood - printing on any surface. Screen printing and screen printing inks themselves differ in the type of binder: water-based inks, solvent-based inks, UV-curing inks, plastisols, temperature-fixed inks.

Due to its technological features, silk screen printing allows printing both on flat and cylindrical surfaces, so modern screen printing is used not only in printing, but also in textile, electronic, automotive, glass, ceramic and other industries.

Both direct screen printing, printing directly on the printed surface, and transfer, transfer screen printing, printing on an intermediate carrier with subsequent transfer to the product are possible.

Advertising on shop windows, images and inscriptions on clothes, branded bags with a logo, divisions on the measuring scales of devices, designations on the front panels of devices, key patterns on film keyboards, custom-made volumetric stickers, production of stickers, emblems, nameplates - all of the above are united by one technology polygraphic printing - it's silkscreen.

What do all of these items have in common? The similarity lies in the fact that it is very difficult, and sometimes impossible, to put an inscription or logo on these products and materials, to print an image using common printing methods. To impress ink from the form onto the surface to be printed, a certain pressure is required, which is practically inapplicable, for example, when printing on thin, fragile material. Silk-screen printing is available not only for printing on any surface, but also for applying a thick ink layer of high hiding power, which allows you to cover any color or black background, as well as apply silk-screen printing, fill in the rough and textured surface of the product.

Some difficulties in screen printing cause halftones and multi-color images. This is due to the very nature of screen printing, which makes it impossible to obtain reproductions with letterpress or offset screen lines. The limit of reproduction of a raster image in screen printing technology is determined by the fact that the cells of the grid cannot stably hold the copy layer, especially in deep shadows. But recently there has been significant progress. Screen printing is becoming more and more widespread due to the use of modern color separation technology, new methods of processing copy layers and the use of modern mesh bases for the manufacture of printing plates.

Screen printing has a great future. And although it is inferior to other printing methods in some respects, this is more than offset by the significant advantage of the process and the huge variety of screen printing applications. What is silkscreen? The future of screen printing technology is, first of all, a significant increase in the quality of printed products, expanding the range and increasing productivity, which can be achieved by:

• improvement of printing forms and technology of printing processes
• development of new types of paints, including accelerated methods of fixing them (implementation of UV curing paints, conductive and water-borne paints
• improvement of printing equipment that does not require a long time for preparatory operations, the creation of new generation machines that combine screen printing, for example, with flexo printing, etc.

At present, the development trend screen printing method leads to a revolutionary turn, and in the near future, the silk-screen printing method will not only expand its fields of application, but also significantly increase its productivity.