I made myself a tool to press open seams. Get a large wooden dowel (approx. 1 1/2 in diameter) and nail a strip of lath (1" X 1.5" X 1/4") to it for stability. Sand it if necessary, but make sure it is clean. Do Not put a finish on it. Then all you have to do is lay the seam on top of the dowel, the seam will pop open enough for the tip of the iron to open it the rest of the way. I use steam and no fingers get in the way.