Here are some examples of the default minimum size values of default PaintTool SAI brushes. Default PaintTool SAI brushes have Min Size values ranging from 0-50%. In PaintTool SAI the Min Size slider in the brush settings menu “changes the brush size when pressure is 0.” This affects the size of your brush depending on how much pressure you apply while drawing. You can access this menu through Help > Options in PaintTool SAI ver. Change the minimum pressure settings in your PaintTool SAI options.Check the Min Size of your brush settings and make sure it is less than 100%.Method 2: Change Minimum Pressure Settings.