The size 100 look too small for the Sage, a #2 filter paper will be around 50mm at the bottom straight edge, 90mm along the sides. A #4 paper 110-120mm along the sides.
I wouldn’t use brown papers at all, not without rinsing.
Amazon has Filtropa #4 white papers.
Where do you buy your day-to-day groceries? Do they not have white filter papers?
