I'm a student wanting to paint a 60x72 oil painting of a swan. stylized and monochromatic for high contrast. I wanted to know if it'd be better for me to use linen rather than cotton. i don't want to accidentally indent the canvas while working on it. Is it worth paying the extra cost for the stiffness of linen? ... also, does it need to be sealed afterward? and what products would be recommend if so? ...I'd also appreciate any experienced artist's tips on how to go about creating this! thank you!!
Linen is surely a more stable surface of the two. If you use cotton canvas seal the back with either acrylic gel medium to give it a little more stiffness make sure you are using at least a 12 to 15 oz cotton duck canvas. if you use linen make sure it is a medium to heavy linen weight. If denting or damage is the main concern for something that big I will many times take a 1/4" oak or birch plywood or baltic birch panel cut to size and nested down where the bull nose of the stretcher bars stops so essentially you end up stretching canvas over a wood panel. The panel doesn't touch the canvas since it's on the shelf below the 1/4" or 1/2" bull nose detail on the stretcher bars. That way the painting is protected from the back and limited to damage from the front side as well. I lightly seal my painting after they are painted with Grumbacher Damar Vanish spray cans. Just know this will bond with the paint and become a part of it.
cotton with polyester is good.