Water Transfer Printing explain

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.

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.