A:Answer Hello Barbara. The thickest paper we have tested on the ET-3830 is Epson Premium Photo Paper Glossy, which weighs around 79 lb. If you plan to use cardstock, we have tested similar Epson paper that weighs around 44 lb. Please be aware that these recommendations are for Epson paper only. You can try paper that falls in that range, but your results can vary when using other brands and heavier paper. Regards, Kevin - The Epson Team