u didn't tell, sketches r somewhat thicker in drawing or drawing prints.
if it is in print , try to change the printer settings.
if it is showing in autocad drawing,
please check tools-options-line font for sketch curves line thickess.
thanks,
Regards,
Murugan.S
Sr. Design Engineer,
CAD/CAM Research Center,
GlobalSoft Pvt Ltd,
New Delhi, INDIA.