How-To VideoFlattening Cardboard May 6, 2015September 20, 2015 I use a lot of cardboard as bases for my mixed media pieces. It’s cheap and plentiful, and I like the texture, and the way it accepts paint. Cardboard has one minus: it curls when wet media is applied. Here’s how I flatten it again: Share the creativity...FacebookTwitterPinterestTumblremail Cardboard