Several time a week I get requests to do custom decals and I want to give an idea of what is involved in doing these. Customs are both easy to do and difficult at the same time. The easy part is doing the artwork if there is good information to use. This mostly is good clear photos taken straight on of the subject. This gives me a good pattern to draw the artwork from. The best artwork to use, however, is line drawings if they are available. Why redraw the artwork you ask? Well the answer is this. Photos that are scanned images are one form or another of what is called a Raster image. These include the popular formats such as BMP, JPG and GIF. These images are made up of small squares or pixels. Each pixel is a specific color and may or may not be the same exact shade as the pixel next to it. This is what allows pictures to be realistic. The problem comes in when the picture needs to be resized. To change the size of the picture each pixel is either enlarged or decreased in size. There is a limit as to haw far the image cam be resized before the image becomes blocky looking in the case of enlargements or muddy looking if making them smaller. Most custom decal makers use a image formal referred to as Vector images. These images are line drawings that have the points mathematically calculated by the program. When the image is decreased or enlarged in size these points automatically recalculate to give the new representation of the drawing. By using this type of format the image can be resized infinitely without losing any of the resolution that the original had. Now, you are asking, why don't all computer images use this format? The reason is simple, the color that is in each segment of the drawing can only be one shade. With this restriction pictures would all look cartoon like. Now, Why use this format for decals? The ability to resize the artwork is probably the biggest reason, file size is another one. Vectors are smaller.. If I were to draw a circle logo in a raster image the drawing would have to be drawn at exactly the size I would want it to be printed at. Not a problem for a fairly large logo. But, if the circle had to have a lot of detail work in it the pixels would be too big to give a clear, crisp image. With Vectors I can draw the image at a size that is comfortable to work in , add all of the detail, and then scale it to the size that I need to print it at.
Printing decals and the problems associated with them
Printing decals is a little more involved than just drawing a image and stuffing a sheet of decal paper through a printer. All printers that use color ink will not print a solid fill color over a clear surface. Inks, other than black, are a semi transparent coating. The white background of paper is what allows the ink to be seen at the color it was printed at. To test this, simply open a drawing program such as MS Paint and draw a shape such as a circle or square and fill the image with yellow for the color. Now, print this on a sheet of white paper. It will come out as a yellow shape. Now, print this same image onto a sheet of blue paper. What color do we get? That's right, green. This is because of the inks transparency working with the blue paper. Now, try it with a sheet of black. Yup, the image will not even show up. This is one of the reasons that clear decal film can't be used with color inkjet printers or laser copiers and printers. So, how do you print color decals onto clear decal film? This is where the Alps comes in. This printer has several features that makes it great for printing decals. The most important one being that it can print white. Another feature is that it has an overlay feature. When this is turned on it allow multiple passes to be printed with out loosing registration. This is actually a byproduct of the way these printers work.
Putting it all together
When a decal is designed, all of the different colors are placed onto different layers in the drawing. Layers can be best described as clear transparencies stacked on top of each other. They can also be turned off on on when necessary. Each part of the drawing is in perfect registration with the ones below it and above it. The first layer printed is always the white layer unless the decal is to be all black, the only color that does not need a white undercoat. After the white is put down the other colors can be added. If the logo is to have, say, red and blue parts, The red artwork will only cover where the red is to be and the blue the same way. If they were to overlap at all there would be a purple area where they overlap. When printing white, the alps printer does not see white in the image and call for the white cartridge. It acts the same way as any other printer works. It lets the white of the paper be the white in the image. In order to print white, I have to create a copy of the image onto another layer and fill it with solid black fill. I then have to tell the printer to use another of its unique features, it's ability to Spot Print. Spot printing allow me to put down a solid fill of white where ever the black image is. It has to be black though, if it were gray the printer would only put down 1/2 of the white fill. Once the white fill is printed I turn that layer off and print the rest of the image. This is why I can't take the scanned image and print it. I have to create the white layer under it and raster images do not have the crisp resolution to do this.
This US Salt decal is a good example of this process. This, by the way is a scanned image of the actual decal. All of the lettering on the actual decal is legible and can be read.
The red lettering as well as the blue boxes all have a white undercoat under them. Under the blue boxes in the artwork there are black boxes as well as black letters under the red letters. These black shapes allow me to print the white undercoat only where the color will go. The white U and S are actually the white undercoat showing through the blue box. In the drawing the letters on the color layer are white so the printer will not print there.
I hope this will help avoid some confusion about decal printing and why there is usually a setup fee associated with creating custom decals.
A note about the alps printers.
The Alps printer, although a wonderful machine, does have limitations. Most noticeably the ability to print solid colors other than the spot color created from the three basic cartridges. Cyan Yellow and Magenta. These printers do not use a liquid ink but, rather a ribbon similar to a typewriter or for those born after 1980 a dot matrix printer. In fact the basic method of printing is much like a dot matrix printer but, instead of 20 DPI these have a resolution of 600 DPI. Another problem is the inability to print convincing gray colors.