Decal (decolating) is an image printing technology, mainly on the dishes. Although it can be used for printing on metal, plastic, candles, soap and even nails. Because at its core, the decal is temporary tattoos that we all know from childhood. The temporary tattoos are printed on the special paper, then attached to the blank for printing and glued. But not everything is so simple, the decal process will be described in more details below.
In advertising, the decal is used for printing on ceramic, porcelain and glassware. For printing of the images on other materials there are other, more suitable printing technologies. The main advantage of the decal over other methods of printing on dishes (silk-screen printing, pad printing and sublimation) is the image durability, it is almost eternal, it cannot be erased or scratched with a knife, it is not affected by chemicals, acid and other irritants.
Printing with the decal on dishes consists of the following steps: printing on gummed paper, varnishing, gluing the transparent sticker to the product, firing in a muffle furnace, or coating with the protective varnish. The first thing we need is the gummed paper, it is coated with gelatin or dextrin, these are substances that dissolve in water and help the paint to remain on the lacquer layer. An image is printed on it, most often vector in color by the method of the screen printing, rarely a full-color raster image is printed on a ceramic printer. Then the printed paper is varnished with the colloidal decol varnish over the print. After that, the paper is moistened with water and gelatin which is between the coverage with the varnish and the paper, is soaked, and we carefully remove the paper, getting a transfer or a decal. We attach this decal to the blank, for example a cup, and wait until it dries. The cup should be degreased, free of dust and if there are air bubbles, they should definitely be squeezed out. Next, we place the cup with the decal in a muffle furnace where with the temperature of 600-800 degrees the lacquer burns out and the print with the decal colors is roasted in the glaze layer of the cup and remains there forever.
The universal process of printing with the decal is described above but in general it is divided into hot and cold, by color and full color, they have different properties and results. The most common in advertising is the hot decal by colors printed with the silk-screen printing. The hot decal ends with the process of roasting the blank with the decal in the oven. You need to print the image on paper with the special decal colors, others will burn in the firing process. This causes not very large selection of colors, not all shades can be obtained with the decal colors. Also after roasting, the shade of the paint changes, and it is almost impossible to make an exact color according to the pantone. A big advantage of the decal is the ability to print on any surface of the product: on the handle, on the bottom, on the inside, on any bends and uneven surfaces. This cannot be done by the screen printing, the sublimation, or the pad printing. Roasting should be done according to the technology, the furnace should be heated for a long time ahead and evenly so that ceramics, glass or porcelain will not burst. It is best to place there the product which is already heated to the temperature of 20-30 degrees. Before putting the product into the furnace, it is necessary that the decal is dry on it, you also need to wait for the blank to cool down in the furnace after roasting. The roasting temperature can vary depending on the material: glass, ceramics, porcelain, faience, also from the manufacturer of the dishes, they are different in properties and colors that will withstand the desired firing temperature but usually it is 650-800 degrees Celsius. When implementing the decal you need to take into account the samples of firing on the temperature threshold about 3-5% of the total circulation.
The cold decal is similar in its process to the hot one, only at the end there is no kiln firing. Instead of firing, the decal is coated on top with a layer of the protective varnish. The cold decal is used most often for the full-color decal on the dishes. Since only ceramic or decal colors can withstand the temperature firing, the full-color printing is most often done using the cold decal technology. It allows you to print a full-color image with the ordinary paint and after coating with the protective varnish, the dishes are ready for use. Indeed the wear resistance of the cold decal is significantly inferior to the hot one. For example, the temperatures above 200 degrees will melt it, it is impossible to wash it in the dishwasher, there will be mechanical damage, such dishes are more suitable as the souvenir products that will sit on the shelf and please the eye. The cold decal is similar in its characteristics to the sublimation but it is cheaper as for the cost, it is done faster, it is possible to cover the surface of any shape. But still much inferior to the hot decal which is used in 90% of the printing on cups and plates.
Let us summarize the printing results with the decal and list the main disadvantages and advantages of this printing technology.
- Printing by color, mainly 1, 2, 3 or 4 colors.
- Long printing time: the decal should dry on the product, then the product should be heated up systematically, then burned, then cooled down. The furnace contains a certain number of the cups, then the process repeats.
- For printing, you need a print run, preferably from 100 pieces. Long preparations for the process, preparation of a sieve for printing with a stencil, heating of the furnace, and so on make the printing of fewer than 50 pieces meaningless
- Durable printing: it does not wash off, does not get erased, does not fade. Thanks to roasting in the furnace, the print and the cup become one unit.
- Printing on the surface of any shape. You can print on the pen, inside of the items, at the bottom of them, around the perimeter of the product, for the decal there is almost nothing impossible.
- The best choice for printing on the crockery in large quantities price-quality-time of manufacture. And as for the quality this method is the most durable one, at a price almost the very lowest, in terms faster than the other types of printing on large print runs.
In general, when printing with the decal is performed, there is a number of nuances, complexities, and features that are too long to be described in one article. Much of the success of printing with the decal depends on the experience gained in the process of firing and manufacture of the decal. In our advertising agency ‘Vmeste’ you can order printing with the decal on any ceramic, glass or porcelain product, and do not worry about price-quality-time. Contact us, we will be happy to help you.