History – Formstone
Formstone was a man-made stone patented by Albert Knight, a Baltimorean, in 1937 but it is also known as Perma-stone, Rostone, Tru-Stone, Fieldstone, Bermuda Stone, Modern Stone, Romanstone, Magnolia Stone, Dixie Stone and Silverstone. However, Formstone has become the more common name used.
Formstone was a plaster compound that was applied in multiple layers to a wire lath attached to existing exterior walls and then scored with simulated mortar joints to make it appear as individual stones. Coloration was also used and sometimes mica chips so they would sparkle in the sunshine. Plaques were embedded by the front steps indicating which company manufactured the Formstone.
Formstone became very popular to residents, business owners and even religious institutions who wanted a maintenance-free covering for their old porous brick exterior walls. Salesmen bragged of its superior sealing assuring a lifetime of leak-free walls and peeling paint. However, over time Formstone can crack and even pull away from the wall, creating a pocket where water can seep into. Today, many homes in the neighborhood have been restored to their original brick façade but several with Formstone, including the plaque, can still be found.
(Data condensed from www.wickipedia.org)