Canvas is a durable, thicker fabric, used from everything from totes to curtains. However, the thick weave -- while desirable from an aesthetic and longevity perspective -- makes it somewhat difficult to get perfectly flat. Creases and wrinkles that commonly occur on unrolled canvas are removable, but plan on investing a little time for the process.
Mix water and 1 cup white vinegar in a standard-size spray bottle. The bottle should be close to full.
Lay the canvas item flat on a clean surface.
Saturate the material with the water and vinegar combination. Let this set in for a few minutes.
Hang the canvas fabric or article on a clothesline at the very end, using clothespins. Keep it out of direct sunlight if the piece has rich color in order to prevent fading.
Set your iron to its highest setting, usually reserved for cotton and linen.
Place the article on the ironing board. Lay the damp cloth over the fabric.
Press firmly on the canvas fabric with the iron, constantly moving the iron to prevent scorching your cloth.
Repeat the process until the item is satisfactorily smooth and flat.