The Suji are typically much smaller (less than 1 Bun 分 which equals about 3 millimeters). But in this scroll, a thicker, black 3 Bun Suji was used to help provide contrast with the light, pale blue cloth.
I did not use Ichimonji to border the work, but what I did do was take Fukushima Silk 福島絹 and put that between the work and the Hada Urauchi (First Layer of backing paper). Although very light in both texture and color, this provides just a hint of the same cloth color around the Enso circle. (A deeper explanation on the Enso meaning is provided in a previous scroll translation.)
What I was trying to achieve was the Blue (In & Around the Enso), Black (Calligraphy Work), Blue (Cloth), Black (Suji), Blue (Cloth) and Black (Jikusaki). This provides a rounded overall feel of balance and coordination.