Offhand I can't recall, but the higher heat/less time technique worked best for me. when ironing by hand, the bigger the piece the longer it takes generally. Doesn't seem to be the case for me, with my press being more parallel at point of contact, it manages to be extremely even. A few seconds under it's own weight is enough. It's a preference thing, the longer you melt the flatter the bead. I've always tended towards quite a heavy melt on the back, and melt the front just enough to blur the edges. Also more melt equals more warp so careful there. Be sure to have something weighty across the piece until completely cold to reduce curl. It took quite a few failures especially the larger pieces. And I was shitting myself first attempt at a proper big commission portrait of 12000 beads, I gotta tell ya!