milled graphite powders whose thickness is typically $>$100 nm and Few Layer Graphene (FLG) with layer numbers of 2 to about 5 and Multi-Layer Graphene (MLG) with layer numbers of between 2 and 10. We use the term “graphene powder” to describe the starting 2D graphitic material as it is a term used by the manufacturer. The slurry is then processed by the three-roll mill six times until it assumes a glossy, paste-like appearance. Figure \[panel1\] depicts photographs and scanning electron microscope (SEM) images of the graphene ink as it is processed through the three-roll mill from pass 1 to 6. With subsequent passes, improved dispersion of the graphene flakes into primary particles within the ink gradually lowers the sheet resistance (R$_s$) and measurement variability from different areas of the print; Fig. \[panel1\]b. The R$_s$ saturates at 6 passes and does not improve further with increasing three-roll milling; Supplementary Fig. 6. In our experiments, it is able to achieve separation of the graphene agglomerates from an average flake diameter of $\sim$90.5 nm to $\sim$40.6 nm and an average thickness from 12.4 nm to 2.5 nm; supplementary Fig. 2. Raman measurements of the graphene powders before and after ink formulation do 