Originally Posted by theBongolian
agreed. Not critical but the hardboard (masonite) is also sold in 3/16 thickness, which would give just a tad more stiffness. Another thought is they sell "white board" - which is hardboard with one side coated to a slick white - which is used for dry erase boards. If a (very )slick white surface would be helpful then consider that -
I should have stated that the hardboard at Lowe's (and Home Depot) is not actually 1/4". The 1/8" inch thick but the thicker stuff is as you stated, 3/16ths, a 1/16th of an inch thinner than 1/4". Though you can find actual 1/4" tempered hardboard, it is far less common, often special order only.
The idea of the white finished tempered is a good one for a drawing board. It will last a lot longer if you use masking tape than will plain hardboard, even if sealed.