Hello. The thickest paper the ET-4850 can print on is Epson Premium Photo Paper Glossy which weighs 79 lb. For cardstock, we have tested similar Epson paper that weighs around 44 lb. These recommendations are for Epson paper only, you can try a cardstock that falls somewhere in that range, but your results can vary when using other brands and heavier paper. Regards, Kevin - The Epson Team.