Hydrographics or HydroGraphics, also known as immersion printing, water transfer printing, water transfer imaging, hydro dipping or cubic printing, is a method of applying printed designs to three-dimensional surfaces. The hydrographic process can be used on metal, plastic, glass, hard woods, and various other materials.
The exact origin of the water transfer printing process is unclear. However, the first hydrographic apparatus registered for a US patent was by Motoyasu Nakanishi of Kabushiki Kaisha Cubic Engineering on Jul 26, 1982. Its abstract reads [a] printing apparatus provided with a structure which supplies a transcription film into a transcription tub containing a liquid so that the transcription film is kept afloat on the liquid, a structure which makes the liquid flow in a direction in which the film is supplied, and a structure which slantingly immerses an article to be printed into the liquid in the transcription tub from an upstream position to a downstream position of the liquid.
The water transfer printing process is extensively used to decorate items that range from entire all-terrain vehicles and car dashboards, to small items like bike helmets or other automotive trim. Films can be applied to all types of substrates including plastic, fiberglass, wood, ceramics, and metal. For the most part, if the item can be dipped in water and can be painted using traditional techniques then the hydrographic printing process can be used.
In the process, the substrate piece to be printed is pre-treated and a base coat material is applied. A polyvinyl alcohol film is gravure-printed with the graphic image to be transferred, and is then floated on the surface of a vat of water.
An activator chemical is sprayed on the film to dissolve it into a liquid and activate a bonding agent. The piece is then lowered into the vat through the floating ink layer. The ink layer along with the polyvinyl alcohol backing then wraps around and adheres to the item. The adhesion is a result of the chemical components of the activator softening the base coat layer and allowing the ink to form a bond with it. One of the most common causes of a failure to achieve adhesion between the two layers is a poorly applied activator. This can be either too much activator being applied or too little.
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