His work rivaled the beauty of medieval windows and added new resources by his use of opalescent glass and by his original methods of layering and welding the glass .
La Farge experimented with problems of shifting and deteriorating color , especially in the medium of stained glass .
La Farge 's work rivaled the beauty of medieval windows and added new resources by his use of opalescent glass and by his original methods of layering and welding the glass .
La Farge experimented with problems of shifting and deteriorating color , especially in the medium of stained glass .