White Underbase Screen Printing
An underbase is a layer of ink that is printed as a “base” on a dark shirt for other colors to sit on. This gives the top colors more brilliance. Since the underbase is generally a high opacity ink, it is flash-cured before the top colors are printed over it. Not only does underbasing slow production, but it is often an extra color that the customer did not plan on.
An under base is usually done with white ink. The reason for this is that the white provide a very neutral color for the other ink colors to be printed on top of. It is also the lightest color so it provides better results on darker shirts. The way the process works is that the screen printer will print a wide layer of ink underneath every color in the design. This provides a base canvas for the rest of the colors to then be printed on top of. That way it is almost like printing on white shirts instead of darker shirts.
You may be concerned that this layer of white will be visible in the final, finished product. However, when done properly the customer should not be able to see the under base at all and if they did not already know they wouldn’t even know it was there. If there is a problem with printing whereby the shirt or equipment moves during printing, resulting in being improperly lined up, then it is possible that some of the white under base will show. However, in most cases this is no more of a problem than it would have been anyway, since that same jarring is likely to result in a generally unsatisfactory, crooked print. Quality control should catch an error like this without it ever causing problems for the customer.
Under basing is a very useful tool in the industry and it can be invaluable for printing light ink colors on darker shirt colors.