The knockout method is when you create a design that gives the illusion of layered heat transfer vinyl (HTV), but there is no layering done.
To do this, create your design in your software so there is no layering present. This varies by software. Then, cut and weed each piece. Tack down (only press for two to three seconds) your first layer(s) and continue until your final layer, which you will apply for the full application time. This will ensure your vinyl does not shrink, as well as keep your pieces lined up. It’s like putting a puzzle together!
You would most likely use the knockout method in two scenarios: when working with HTV that cannot layer or when working with a design that would require a lot of layering. A lot of layering means your garment gets too thick and bulky. The knockout method can eliminate that issue.
Source: Brooke Hestdalen