First of all, let’s clarify what specialty printing is.
Different from office printing that mainly presents text and simple graphic on paper, specialty printing delivers printing with intricate design and multiple colors on diverse materials, including fabric, metal, acrylic, etc.
With rapid development of printing technology, specialty printing evolves from manual methods like screen printing to digital methods including Direct-to-Film (DTF), Direct-to-Garment (DTG), Ultra-Violet (UV) printing, and so forth.
In most digital specialty printing methods, white ink acts as the base layer of a printing. Now we come to the second question - why a base layer is needed?
As previously mentioned, specialty printing can be applied on a wide range of materials which exhibit different absorption of ink. Take fabric printing as example. Among all fabrics, cotton is known for its high water absorption capacity compared to other fabrics. Direct printing on it may cause incomplete graphics or evident color inconsistency.
A base layer under the final print can effectively reduces negative effects brought by the desired substrate. So, why the base color has to be white ink?