If you like the look of multipaned windows but don't want to go to the expense of replacing your windows, a Southland firm has an economical alternative: removable plastic mullions.
Insta-Panes by Mansion Industries, City of Industry, are available in a number of kits with materials to create multipaned windows with areas ranging from 12 to more than 60 square feet. If you need to do a substantial number of windows, you'll have to buy several kits or one of the larger kits. The largest kit will handle a sliding patio door.
Made of the same kind of weather-resistant polyvinylchloride (PVC) used for exterior siding, the strips are cut to size with household scissors, fitted into L-shaped, T-shaped and cross-shaped connectors and attached to the window glass with pressure-sensitive Velcro fastening tape.
Velcro makes the Insta-Pane strips easily removable for cleaning, according to Steven A. Zieg of Mansion Industries.
The thin strips leave something to be desired if you are seeking a truly authentic look; traditional window mullions have a three-dimensional appearance lacking in these flat strips.