 If deterioration of the litharge is found, it is likely that the prisms are not properly secured within the frame structure of the lens.If the litharge is white in color (lead carbonate) the material is mostly non-porous and may not easily be preserved, meaning that full litharge replacement might be necessary.If the litharge present is orange-red in color (lead-oxide), this substance tends to be more porous and may allow for stabilization.