What is it?
Butt registration also referred to as "butt fit" and "kiss register," is the process of aligning two or more different colors directly next to each other without allowing the colors to overlap or allowing any space or gaps in between. The colors actually butt up against each other, hence the name. To best utilize this process and achieve the desired results your alignment and registration will be critical factors because any misregistration will be noticeable.
When would a decorator use it?
A decorator would utilize this process to prevent overlapping and the results it may produce. It's also used to avoid another method known as trapping. The butt registration process can create a more defined transition from one color to the next, and in some cases, the artwork itself will demand it to yield better results.
Tips and tricks
When utilizing the butt registration process keep in mind that there is zero room for registration issues. An auto press is your best bet to ensure consistency in squeegee pressure and other variables. Make sure the registration is tight on your press, and make sure your screens are tight as well. This will help keep things properly aligned. If you are just off registration, using a choke may help you accomplish the desired results. A choke is used to increase or decrease the outer edge of your image. A registration system can offer a world of help as well. Always maintain your equipment for peak performance and use the proper tools. Proper tools can help reduce your time and mistakes. Once you have achieved the desired results, notate your methods to help you consistently achieve those desired outcomes.
Source: Kirk Harris