I can always count on the knowledgeable staff at Antique Lamp Supply.
"I inherited a lovely Art Deco desk lamp, in great condition other than missing the fitter and shade, that as a result had been languishing in my attic for years. I emailed Antique Lamp Supply a description of the lamp and how I thought the original fitter attached and the technical staff directed me to the proper fitter. I was able to buy it in unfinished brass so I could darken it with brass darkener to the same patina as the lamp. Problem solved!"
