The Balthus knot, also called the double Windsor, is the perfect large necktie knot for an elegant look or formal setting.
The Balthus is the largest knot I'll cover. It takes the Plattsburgh's over the center, under to a side step one step further. It begins with the wide end under the narrow end. Bring it over the center, under to the right, over the center, under to the left, over the center, under to the right, then wrap it over to the left, under to the center, and tie. The result is a large knot with the widest opening so far.
Inside out, wide end under: C R C L C R L H C T
How to read these steps:
"Inside out, wide end under" means the tie is reversed. The starting position is the wide end taken to the left, under the narrow end
R and L: Take the wide end to the right or left
C: Take the wide end to the center, the area between the knot
H: The step before the last move; put one or two fingers in the knot, as you will soon need space to thread the tie through it.
T: Pull the end end through the loop created by the H. Pull the wide end to tighten the knot, pull the narrow end to pull the knot closer to the collar.