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!!