Film Separations

Films are not colored. They each look the same and all appear to be using black as their emulsion. The same way a black & white laser printer works, the film comes out of the printer one sheet at a time. They are emulsified or printed with dots in the area that needs that particular color or tint. This is known in the industry as a percentage of, or density information, for each color being printed.

Where's the color?

A standard Offset Press uses the CMYK color mode (C = Cyan, M = Magenta, Y = Yellow, K = Black). It's possible to make countless different colors when using varying amounts of each color in combination. To make the printing plates the artwork needs to be broken down into the four CMYK colors. From there, film negatives are made.

To the left;  You will see that our nice pile of fruit has been seperated into the four channels of color. If we then send this information to an Image Setter (that's the device that prints the film) out will come our 4 pieces of film with a label for each of the 4 colors. The film is then used to create printing plates, which are then mounted onto the CMYK Offset Press rollers.  When the printing plates come in contact with the CMYK rollers, the image is printed back onto the page. 

Your Photoshop program can separate an image into CMYK plates too.  In the image shown below you will see that the software automatically separates the image into the four individual CMYK channels, plus it also shows a 'combined' channel.

So what does this all mean?

Not much, unless you are planning on understanding the nuances of offset printing and how many variables are involved.  It takes a lot of practice and expertise to ensure files on the computer get to the page.  The more the client know about the process, the better chance things will turn out as expected. 

FILM SPECS FOR SILKSCREENPRINTING (PMS/Spot or CMYK):
• Positive, emulsion up, round dot, output resolution 2400 dpi, line screen 100 LPI
• Film angles: Yellow: 0 / Magenta: 75 / Cyan: 15 / Black: 45
• Film must be free of pinholes, contamination, creases, scratches, etc.
• All layers must be labeled with the job number, project name and date.
• All layers must be labeled with the appropriate PMS colour # or CMYK value.
• All layers must be labeled with the type of product being printed (CDROM, DVD5, etc.)

FILM SPECS FOR OFFSET CMYK PRINTING:
• Negative, emulsion down, round dot, output resolution of 2400dpi, line screen 200 LPI
• Film angles: Yellow: 0 / Magenta: 75 / Cyan: 15 / Black: 45
• Film must be free of pinholes, contamination, creases, scratches, etc.
• All layers must be labeled with the job number, project name and date.
• All layers must be labeled with the appropriate CMYK value.
• All layers must be labeled with the type of product being printed on (CDROM, DVD5, etc.)