It doesn’t take a genius to figure out after just a single glance that sash windows can be uniquely challenging to paint. Not only do they present the same issues as any standard type of window, but there are also those pesky mullions to address too – often dozens of the things. The mullions are the little bits of added framing that hold the smaller panes of glass in place, or in some cases just sit on top of the glass and make it look like they’re in fact smaller frames.