Nice brass lamps tend to have a laquer finish on them to protect the brass sheen. If you plan to polish them, you are going to have trouble. The laquer does not come off easily, so only the exposed spots will get polished. You will end up with a very uneven finish.

Try to see if there is a Stiffel site and what they recommend.

Remove the laquer with acetone.....then polish.
But consider the fact that the finish was meant to look "crackled".
I have a Stiffel lamp that is easily 40 years old....a.nd the brass looks fine. I have cleaned it with a damp cloth.
Linda C

Leave them alone and don't try and polish them. If they were the Antique Brass that is under the sealant. I have 11 of these lamps and the first one I puchased when I was 18 and will be 56 this June. I purchased the matching table tray lamp when I turned 30. Thay are just great! I just wipe mine down with a damp cloth and dry them as I go. I have changed the shades many times through the years but don't ever try to polish them. My former MIL used Brasso on her's and ruined them. That killed me as they were a Christmas gift from me the second year I was married. I don't know what I was thinking as they sat upon fake, Formica ends tables, with a 35 year old $200 sofa bed between the 2. My X did learn from me but her parents were not able to be taught anything.

Glad you told me about the Brasso. We have some and I was tempted to try it!