I have not framed any posters yet, but I have seen plenty of framed posters that have the signature "rippling" effect. Is this an inevitable side-effect of displaying posters in a frame?
What kind of frames are you using??
Rippling is less of a problem with the HPFs but I recommend that you only use one metal spring at the top center behind the foam board. The metal springs can create permanent waves.Also, never try to squeeze a poster into a frame that is too small. See this thread for tips on that:http://www.allposterforum.com/index.php/topic,6042.0.html