I block the panel before using. Tape down one selvedge edge and one cut edge. I use my 12.5 inch square ruler to get a true 90 degree corner. Then spray to dampen and maneuver the other two edges into position. Measure each opposing edge to make sure they are the same length and also measure diagonally. Tape down and spray until wet. Leave to dry and then press. I have always had good luck with this method.