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Silk Screen Printing vs. Digital Printing,
and Cast Vinyl vs. Calendered Vinyl

 
Is there anyone else in this car restoration business who screen prints their decals? We don't know of anyone (in spite of what some may claim)!
 
 Our printed decals are custom made to our exact specifications, using the same 100% authentic silk screen printing process that was used back in the day, when the original decals were made. The initial setup cost of silk screening is considerably higher than the minimal setup requirements of digital inkjet printing, but the result is an impressively higher-quality product that looks just like the original and will last significantly longer than an inkjet graphic.
 Silk screen printing has been around for many centuries. It is a process that uses a fine synthetic fiber screen or stencil with a design burned into it, on which ink is squeegeed through the openings left in the screen after exposure, and transferred to the printing surface. Silk screen ink is applied many times more thickly than digital ink, and the resins in these screen inks are aided by the solvents in embedding themselves into the surface of the media. This embedment results in extended UV and abrasion protection. The solvents then must be allowed to evaporate or outgas before lamination.
 Full-solvent inks use stronger chemicals and penetrate more deeply than eco-solvents, and therefore have a longer outdoor durability of five years without clear-coating, versus three years for eco-solvents. Our decals are given a final clear coat of ink to increase UV protection and hold brighter colors for even longer. This step is typically omitted with digital printing, as the clear coat tends to dull the colors. The inks in our decals are matched individually with the clear coat included, to make sure they are correct. We use transparent screen solvent inks on any decals that were originally printed on reflective vinyl, so the reflectivity shows through all of the inks, not just where there is no ink, like digital inkjet graphics do.
 Bitterness of low quality.
 Screen printing uses the RGB color model, which has a much larger range of colors than digital printing’s CMYK process color model. Pantone’s precise color matching system can be used to custom mix the inks for 100% accurate colors. Pantone spot colors number over 1,100, most of which are outside the CMYK gamut.
 Process color means the four colors of yellow, black, cyan and magenta are mixed by the inkjet printing device in different percentages of dots to create a range of colors. For this process to work properly, reflected white light must be the starting point. This is why all digital inkjet printers must print on white media or lay a white under-base. Digital inkjet printers typically cannot print white ink. In contrast, screen printed graphics can be printed on dark substrates by using two layers of ink. This makes it possible to print decals such as gauge faces with white ink on black vinyl.
 Our artwork is produced from original decals, not from repros, and the artwork is created with hand-drawn lines and curves that provide the necessary information for a plotter to follow. These vector images are the most desired type of graphic files for printing. They can also be resized without loss of quality. The least desirable type of graphic file is a raster or bitmap image, such as a jpg, that is made up of a multitude of pixels. When resized, there is often a loss of quality. Vector artwork produces noticeably more precise and crisp printed images.
 The highest quality graphic films, which we always use, are not designed for digital inkjet printing. 3M premium 2 mil cast vinyl, and 3M premium 680 series reflective vinyl are designed for screen-print solvent ink. The surface treatments used to produce the desired levels of gloss on these products will deter inkjet ink’s ability to sink into the surface. The result will be inferior UV and abrasion resistance, and less vibrant colors. Vinyl features like brightness and ink absorption are key to optimal image quality. Outdoor durability ratings for graphic film, assess UV resistance for vinyl that is in a vertical position. These ratings do not guarantee that the design printed on the vinyl will have the same durability.
 3M manufactures intermediate quality 4 mil polymeric calendered vinyl that is compatible with digital inkjet printing, using latex, UV, or solvent inks. Water-based inks such as latex, have very limited durability and tend to fade quickly because the ink sits on top of the surface, rather than sinking into it, and they cannot be used with uncoated media. UV-cured inks also don’t use solvents to protect the ink from UV exposure, and consequently can become uncured, and fade in direct sunlight. Most UV inks have a satin finish which negates the gloss or matte characteristics of the media. For the best digital graphic results and greater durability, solvent-based inkjet ink must be used.
 Cast vinyl is formed in a manner similar to pouring batter into a pan when baking a cake, while calendered vinyl is rolled out like pie dough. Cast film has the lowest shrinkage, cracking, and peeling of all vinyl films because the film itself has not had any stress applied to it during the manufacturing process, so it does not try to shrink back to or resume its original form. In contrast, calendered vinyl is squeezed through a series of rollers until it is the desired thickness, which causes it to “remember” its original form and want to return to it. Since calendered vinyl is meant for more temporary applications, cheaper raw materials are generally used in its production. Cast films can be made very thin, which produces a conformable product that allows application over substrates with curves. Cast films also maintain their color and other properties better than other vinyl films. Cast vinyl films with air-egress release liners have almost eliminated bubbles and wrinkles from applied graphics.
 Calendered Vinyl Shrinkage.
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