The screen printing frame is the printing machinery associated with screen printing processes. It consists of a wooden, plastic or metal frame and a polyester canvas anchored to it.
Since the screen printing mesh attached to the frame can be more or less dense, it is possible, by change them, to choose how much screen printing colour to print on each product in order to obtain thick or full-coverage colour spreads.
To define the density of a screen printing mesh, one specifies the number of threads from which it is composed and their thickness (in microns). Knowing the number and thickness of the threads in the screen-printing mesh, one can calculate how many grams of ink per square metre are consumed when using it. This information is therefore very useful when budgeting production costs.
To transport the graphic onto the screen-printing frame, the canvas is coated with a thin coating of UV-reactive gelatine. The artwork is then transferred onto a transparent film, and the film is placed in close contact with the surface of the screen-printed canvas inside a bromograph.
In the bromograph, the gelatine that is not covered by the graphic printed on the film is hit by UV rays, polymerises and becomes rigid. The remaining emulsion (the one hidden by the graphics) remains soft and can be removed from the frame with a jet of water. At this point, the system is ready to be used in printing, as the gelatine-free parts will be permeable by the inks. A screen printing implant is required for each screen printing pass that is performed.
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