Print or transfer decors
Methods There are various ways to apply images, text, and logos to promotional items and hollow packaging containers.
Process To apply images, fonts and logos on promotional gifts and packaging hollow bodies, there are various options.Especially before important trade fairs or before the end of the year, many advertising managers think about what they want to distribute as more or less useful and original gifts. Then you have specialized service providers decorate items of all kinds with company logo, slogan and web address. Decorating - the technical term for the direct printing (body printing) or indirect transfer of subjects onto objects - is not just limited to promotional gifts, however. In addition to giveaways and give-aways, there are also mass-produced everyday objects and hollow packaging that need to be decorated. The size, shape and material of the objects to be decorated are almost unlimited. Processes are therefore needed that can be adjusted as flexibly as possible to the variety of objects. Many decorating tasks could be handled with several processes; in the end, economy, design and necessary ink film thickness determine the respective choice of process (see box "Decorating processes").
Really tastyThat tablets and pharmaceutical capsules are printed with food coloring is not surprising. Something special is the printing of chocolates and pralines with colored chocolate mass or colorful paste, sometimes in combination with individual molds - there are almost no limits to creativity. There are even special food screen printing machines for this purpose, e.g. the RukoPrint RP 2.2. The repertoire of chocolate printing ranges from small confectionery runs to large industrial runs of hollow bodies, e.g. Santas and Easter bunnies. Traditionally, Switzerland is one of the chocolate printing pioneers.
Printing on objectsMany print service providers specializing in printing on objects and textiles use screen and pad printing machines together. Both screen and pad printing machines are designed similarly according to certain logistics scenarios. For example, there are timed lines with printing stations that the object passes through, or the printing module is located above a rotating rotary indexing table on which the objects are positioned, printed and ejected. Other solutions provide for a vibratory feed and discharge of the objects. There are also carousel machines in which four or more printing modules rotate above the object and are lowered one after the other for printing. In rotary pad printing, the mostly small objects run closely above and next to each other on conveyor chains.
In screen and pad printing, precise and secure positioning of the objects is essential. For many objects to be printed, a precisely fitting counterpart is required that acts as a reliable holder. This is because universal conveying, gripping and clamping tools are not always sufficient. The suitability for certain object sizes is also reflected in the dimensioning of the machines. For example, there are a large number of dedicated machine concepts. These are also combined with screen printing modules, e.g. for white priming in CD or glass printing.
Digital printing is on the riseThe days are over when Indigo, a supplier of digital printing systems, frantically sought exotic marketing opportunities and adventurous applications. Indigo Omnius, introduced at the drupa 95 trade show for direct and individualized printing on beverage cans, disappeared from the portfolio after a few systems were sold. Today, under the HP Indigo name, "industrial printing" essentially refers to the printing of two-dimensional objects such as mouse pads and plastic cards.
For two- and three-dimensional objects, the inkjet printing process is more recommended than ever. It has long since moved beyond the stage of simply marking screw caps, lids, can bottoms, folding boxes and other packaging with expiration dates. Two-dimensional items such as CDs, plastic cards, mouse pads and leather are easy exercises.
Flatbed printing systems are on the rise, using optimized UV inks to effortlessly print on rigid substrates several centimeters thick: signs, doors, ceramic tiles. They are thus conquering further territory from screen printing, and even large-area white preprinting is already on offer.
After the Durst Rho, several systems are now entering the market: Lüscher JetPrint UV, Spühl Virtu rs and Zünd UVjet from Switzerland, and Gandinnovations JetiUV, Grapo Octopus, Inca Columbia/Spyder, NUR Tempo L, Océ Arizona UV, Tampoprint CP/DMD and Vutek PressVu UV from the rest of the world.
The Tampoprint DMD U 1500 occupies a special position: In special versions, where the print module is locked correspondingly high above the flatbed, it can print objects up to one meter thick, e.g. complete refrigerators. Even curved and structured objects are no problem for it: photorealistically printed engine hoods (was on show at drupa last May), garage doors and radiators, beer garden benches and tables printed with advertising, furniture decorated with imitation wood. In addition, the DMD U 1500 can handle all types of inks. German Tampoprint, one of the largest pad printing machine manufacturers, sees the inkjet process as a digital complement - just as it has been for years for screen printing.
Indirect decorationOften it is disadvantageous or impossible from the production point of view to print the items directly. One way out is the printing and transfer of pre-prints. In such cases, either labels, sliding images and decorative webs are printed, with which the objects are equipped, or the materials from which the objects are later formed. In addition to the respective printing technology, a transfer technology corresponding to the object is then also necessary - usually an intermediate carrier material and a device for transferring the pre-printed subject. In principle, this extends the range of printing processes that can be used.
Labels and stickersThe most trivial solution is offset or flexographic printing of labels, which are then applied to glass or plastic bottles, for example. Also common are self-adhesive stickers from the screen,
Offset, flexo and digital printing. With or without printing, cutting plotters prove advantageous for lettering shop windows, car rear windows and doors, and walls for trade show booths.
DecalsMore demanding is the production and transfer of decals - the new collective term for decals and decals. These printed products are often confused with one another, but they are clearly different. The only thing they have in common is printing on a special carrier paper that has a water-soluble layer to transfer the images to the object after a water bath. The water bath causes the upper paper coating to dissolve, so that either the backing paper can be peeled off after application to the object surface (decals) or the images can be slid onto the object surface on the dissolved layer residues (slides). The different application results in opposite printing sequences: In decal printing, a waterproof, membrane-forming primer (slide varnish) is printed, followed by opaque white, if necessary, and then the colored printing inks in side-by-side reproduction. In the case of decals, everything is reversed: first the colored inks are reproduced laterally, then the top coat of varnish, which also forms a transparent membrane that reliably carries the printed image after the water bath. So-called scribers, which are otherwise printed like decals, manage without a water bath.
However, other criteria determine the printing process to be used. Screen and offset printing are the first choice if no further processing step follows the transfer - i.e. when applying to plastic (e.g. model railroad cars, toys, appliance housings, computer keyboards), wood (toys) and optical glass (windows, eyeglasses). If baking or glazing and firing is required after application, special inks are needed. Firing (approx. 630 °C) is mainly practiced on thicker or tempered drinking glasses to preserve the glass firing colors scratch and dishwasher resistant (see e.g. www.rastal.ch). Ceramic firing colors are required for ceramic tiles, decorative ceramics and porcelain mass-produced goods; here, the decals are transferred to the rough object surface before the entire object is covered with a glaze, which is finally fired at up to 1400 °C. The glaze is then applied to the glass surface. Although such inks can also be formulated on a molten glass basis, they must also compensate for a color change that occurs as a result of the glaze firing. As if the challenge to color management were not great enough, the specific color change depends not only on the temperature, but also on the ink film thickness! Therefore, the ceramic firing colors must be printed in exact layer thickness. This is only possible in screen printing with optimum stencil thickness and mesh quality or in sheetfed gravure printing with lasered and depth-variably etched printing forme cylinder.
Iron-on and stick-onMany copy stores offer "Your photo on your T-shirt" or "Motif of your choice on your coffee mug". The fastest way is to print side-to-side with a digital color copier or color laser printer onto a transfer foil, from which the printed image is ironed onto the T-shirt in special hot presses. Copiers and inkjet printers are suitable for transfer via foil onto coffee pots and similar souvenirs. Comparable processes also exist for screen printing foils, then mostly to transfer the image onto textiles and baseball caps using transfer devices with flat or curved printing surfaces.
Decorative webs for furnitureRoll gravure printing reigns supreme. A few specialized companies produce tons of wood imitation decors for the furniture industry. The printing forme cylinders must be endlessly engraved without seams, i.e. capable of printing a repeat décor. The printing itself runs within the tightest color reproduction and register tolerances. Before the printers rewind or convert the printed paper web, synthetic resin is applied or the web is soaked in resin as a finishing process. The furniture manufacturers then laminate the decorative papers onto the wood and pressboard parts using cold glue. If high gloss is desired, an additional varnish is applied, which must be polished.
Finally, metal sheets are printed with UV inks and varnish on converted sheetfed offset presses. These metal sheets are often the semi-finished product from which beverage cans, crown caps, metal boxes, etc. are formed and assembled on special processing equipment. Not infrequently, this happens in conjunction with the filling of the packaging.
Decorating methods at a glanceScreen printing The oldest direct decorating method is screen printing. The screen printing form consists of screen fabric, partially covered with stencil material, and the frame. Either the screen fabric is clamped in a frame with medium tension (flat screen) or formed into a drum with high tension (round screen). The ink is applied to the object by a squeegee pressing the ink into the screen meshes, thus forcing out the ink already in the meshes. Screen printing machines are automated to varying degrees; fully automated lines are found primarily when printing on objects that are easy to handle, such as CDs/DVDs, plastic cards, and textile webs. One advantage of screen printing is the high ink layer thicknesses. This allows larger effect pigment particles to be embedded without difficulty. Since the printed image is applied in a raised, tactile manner, screen printing is suitable, for example, for Braille, printed circuits and ceramic slide images.
Pad printing If the ink layer thickness does not have to be particularly high, pad printing is the easiest way: Due to the numerous and easily interchangeable pad shapes and sizes, the ideal way of printing can always be found. Tampons are so elastic that they literally cling to the shape of the object and even reach inside walls. The imaging of the tampon printing clichés always requires consideration of the object surface shape or the corresponding tampon shape. The subjects must be distorted depending on this.
Indirect gravure Indirect gravure is reserved for use in pad printing machines. Flat photopolymer clichés are used in flat form printing. In equipment resembling a contact grill or waffle iron, exposure is through the copy film. Tampoprint developed laser-engravable aluminum oxide clichés as an alternative. Rotary tampon printing requires polymer and metal clichés that are mounted on a cylinder and print masses of small surfaces, such as caps, via rotating tampon rollers.
Metal decorating Metal decorating is over 130 years old and was the very first indirect printing process. Today, metal sheets are printed with UV inks and varnish on converted sheetfed offset presses. (dk)
Printed or engraved Swiss Army Knives are among the most popular promotional gifts.
Computer-to-screen with the Lüscher JetScreen.
Optimum quality is delivered by waterless offset printing with UV-curable inks on CDs/DVDs with Metronic CD-Print.
Computer mice and mouse pads are classics for screen and pad printing.
Rotary knobs for heaters and machines - a case for pad printing. Photo: Printing Intl.
The printing industry and its suppliers present themselves with such giveaways. All possible decorating processes are represented.
Dieter Kleeberg
Really tastyThat tablets and pharmaceutical capsules are printed with food coloring is not surprising. Something special is the printing of chocolates and pralines with colored chocolate mass or colorful paste, sometimes in combination with individual molds - there are almost no limits to creativity. There are even special food screen printing machines for this purpose, e.g. the RukoPrint RP 2.2. The repertoire of chocolate printing ranges from small confectionery runs to large industrial runs of hollow bodies, e.g. Santas and Easter bunnies. Traditionally, Switzerland is one of the chocolate printing pioneers.
Printing on objectsMany print service providers specializing in printing on objects and textiles use screen and pad printing machines together. Both screen and pad printing machines are designed similarly according to certain logistics scenarios. For example, there are timed lines with printing stations that the object passes through, or the printing module is located above a rotating rotary indexing table on which the objects are positioned, printed and ejected. Other solutions provide for a vibratory feed and discharge of the objects. There are also carousel machines in which four or more printing modules rotate above the object and are lowered one after the other for printing. In rotary pad printing, the mostly small objects run closely above and next to each other on conveyor chains.
In screen and pad printing, precise and secure positioning of the objects is essential. For many objects to be printed, a precisely fitting counterpart is required that acts as a reliable holder. This is because universal conveying, gripping and clamping tools are not always sufficient. The suitability for certain object sizes is also reflected in the dimensioning of the machines. For example, there are a large number of dedicated machine concepts. These are also combined with screen printing modules, e.g. for white priming in CD or glass printing.
Digital printing is on the riseThe days are over when Indigo, a supplier of digital printing systems, frantically sought exotic marketing opportunities and adventurous applications. Indigo Omnius, introduced at the drupa 95 trade show for direct and individualized printing on beverage cans, disappeared from the portfolio after a few systems were sold. Today, under the HP Indigo name, "industrial printing" essentially refers to the printing of two-dimensional objects such as mouse pads and plastic cards.
For two- and three-dimensional objects, the inkjet printing process is more recommended than ever. It has long since moved beyond the stage of simply marking screw caps, lids, can bottoms, folding boxes and other packaging with expiration dates. Two-dimensional items such as CDs, plastic cards, mouse pads and leather are easy exercises.
Flatbed printing systems are on the rise, using optimized UV inks to effortlessly print on rigid substrates several centimeters thick: signs, doors, ceramic tiles. They are thus conquering further territory from screen printing, and even large-area white preprinting is already on offer.
After the Durst Rho, several systems are now entering the market: Lüscher JetPrint UV, Spühl Virtu rs and Zünd UVjet from Switzerland, and Gandinnovations JetiUV, Grapo Octopus, Inca Columbia/Spyder, NUR Tempo L, Océ Arizona UV, Tampoprint CP/DMD and Vutek PressVu UV from the rest of the world.
The Tampoprint DMD U 1500 occupies a special position: In special versions, where the print module is locked correspondingly high above the flatbed, it can print objects up to one meter thick, e.g. complete refrigerators. Even curved and structured objects are no problem for it: photorealistically printed engine hoods (was on show at drupa last May), garage doors and radiators, beer garden benches and tables printed with advertising, furniture decorated with imitation wood. In addition, the DMD U 1500 can handle all types of inks. German Tampoprint, one of the largest pad printing machine manufacturers, sees the inkjet process as a digital complement - just as it has been for years for screen printing.
Indirect decorationOften it is disadvantageous or impossible from the production point of view to print the items directly. One way out is the printing and transfer of pre-prints. In such cases, either labels, sliding images and decorative webs are printed, with which the objects are equipped, or the materials from which the objects are later formed. In addition to the respective printing technology, a transfer technology corresponding to the object is then also necessary - usually an intermediate carrier material and a device for transferring the pre-printed subject. In principle, this extends the range of printing processes that can be used.
Labels and stickersThe most trivial solution is offset or flexographic printing of labels, which are then applied to glass or plastic bottles, for example. Also common are self-adhesive stickers from the screen,
Offset, flexo and digital printing. With or without printing, cutting plotters prove advantageous for lettering shop windows, car rear windows and doors, and walls for trade show booths.
DecalsMore demanding is the production and transfer of decals - the new collective term for decals and decals. These printed products are often confused with one another, but they are clearly different. The only thing they have in common is printing on a special carrier paper that has a water-soluble layer to transfer the images to the object after a water bath. The water bath causes the upper paper coating to dissolve, so that either the backing paper can be peeled off after application to the object surface (decals) or the images can be slid onto the object surface on the dissolved layer residues (slides). The different application results in opposite printing sequences: In decal printing, a waterproof, membrane-forming primer (slide varnish) is printed, followed by opaque white, if necessary, and then the colored printing inks in side-by-side reproduction. In the case of decals, everything is reversed: first the colored inks are reproduced laterally, then the top coat of varnish, which also forms a transparent membrane that reliably carries the printed image after the water bath. So-called scribers, which are otherwise printed like decals, manage without a water bath.
However, other criteria determine the printing process to be used. Screen and offset printing are the first choice if no further processing step follows the transfer - i.e. when applying to plastic (e.g. model railroad cars, toys, appliance housings, computer keyboards), wood (toys) and optical glass (windows, eyeglasses). If baking or glazing and firing is required after application, special inks are needed. Firing (approx. 630 °C) is mainly practiced on thicker or tempered drinking glasses to preserve the glass firing colors scratch and dishwasher resistant (see e.g. www.rastal.ch). Ceramic firing colors are required for ceramic tiles, decorative ceramics and porcelain mass-produced goods; here, the decals are transferred to the rough object surface before the entire object is covered with a glaze, which is finally fired at up to 1400 °C. The glaze is then applied to the glass surface. Although such inks can also be formulated on a molten glass basis, they must also compensate for a color change that occurs as a result of the glaze firing. As if the challenge to color management were not great enough, the specific color change depends not only on the temperature, but also on the ink film thickness! Therefore, the ceramic firing colors must be printed in exact layer thickness. This is only possible in screen printing with optimum stencil thickness and mesh quality or in sheetfed gravure printing with lasered and depth-variably etched printing forme cylinder.
Iron-on and stick-onMany copy stores offer "Your photo on your T-shirt" or "Motif of your choice on your coffee mug". The fastest way is to print side-to-side with a digital color copier or color laser printer onto a transfer foil, from which the printed image is ironed onto the T-shirt in special hot presses. Copiers and inkjet printers are suitable for transfer via foil onto coffee pots and similar souvenirs. Comparable processes also exist for screen printing foils, then mostly to transfer the image onto textiles and baseball caps using transfer devices with flat or curved printing surfaces.
Decorative webs for furnitureRoll gravure printing reigns supreme. A few specialized companies produce tons of wood imitation decors for the furniture industry. The printing forme cylinders must be endlessly engraved without seams, i.e. capable of printing a repeat décor. The printing itself runs within the tightest color reproduction and register tolerances. Before the printers rewind or convert the printed paper web, synthetic resin is applied or the web is soaked in resin as a finishing process. The furniture manufacturers then laminate the decorative papers onto the wood and pressboard parts using cold glue. If high gloss is desired, an additional varnish is applied, which must be polished.
Finally, metal sheets are printed with UV inks and varnish on converted sheetfed offset presses. These metal sheets are often the semi-finished product from which beverage cans, crown caps, metal boxes, etc. are formed and assembled on special processing equipment. Not infrequently, this happens in conjunction with the filling of the packaging.
Decorating methods at a glanceScreen printing The oldest direct decorating method is screen printing. The screen printing form consists of screen fabric, partially covered with stencil material, and the frame. Either the screen fabric is clamped in a frame with medium tension (flat screen) or formed into a drum with high tension (round screen). The ink is applied to the object by a squeegee pressing the ink into the screen meshes, thus forcing out the ink already in the meshes. Screen printing machines are automated to varying degrees; fully automated lines are found primarily when printing on objects that are easy to handle, such as CDs/DVDs, plastic cards, and textile webs. One advantage of screen printing is the high ink layer thicknesses. This allows larger effect pigment particles to be embedded without difficulty. Since the printed image is applied in a raised, tactile manner, screen printing is suitable, for example, for Braille, printed circuits and ceramic slide images.
Pad printing If the ink layer thickness does not have to be particularly high, pad printing is the easiest way: Due to the numerous and easily interchangeable pad shapes and sizes, the ideal way of printing can always be found. Tampons are so elastic that they literally cling to the shape of the object and even reach inside walls. The imaging of the tampon printing clichés always requires consideration of the object surface shape or the corresponding tampon shape. The subjects must be distorted depending on this.
Indirect gravure Indirect gravure is reserved for use in pad printing machines. Flat photopolymer clichés are used in flat form printing. In equipment resembling a contact grill or waffle iron, exposure is through the copy film. Tampoprint developed laser-engravable aluminum oxide clichés as an alternative. Rotary tampon printing requires polymer and metal clichés that are mounted on a cylinder and print masses of small surfaces, such as caps, via rotating tampon rollers.
Metal decorating Metal decorating is over 130 years old and was the very first indirect printing process. Today, metal sheets are printed with UV inks and varnish on converted sheetfed offset presses. (dk)
Printed or engraved Swiss Army Knives are among the most popular promotional gifts.
Computer-to-screen with the Lüscher JetScreen.
Optimum quality is delivered by waterless offset printing with UV-curable inks on CDs/DVDs with Metronic CD-Print.
Computer mice and mouse pads are classics for screen and pad printing.
Rotary knobs for heaters and machines - a case for pad printing. Photo: Printing Intl.
The printing industry and its suppliers present themselves with such giveaways. All possible decorating processes are represented.
Dieter Kleeberg
