A:Answer Hello Ronbo442. The thickest paper the XP-970 can print on is Epson Premium Photo Paper Glossy which weighs 79 lb. For cardstock, we recommend using an option that weighs around 44 lb, as similar Epson paper has been tested to work. You can try a cardstock that falls in that range, but your results can vary when using other brands, as these recommendations are for Epson paper only. Regards, Kevin - The Epson Team.