TromboneChat

I sometimes see a Conn 4H, 24H, or 30H for sale that are silver-plated. Do the silver-plated Conns perform any different than brass?

There is a difference.  It's VERY subtle.  You may hear it or you may not.  It's much less than the difference between a lacquer and a stripped horn.  The silver plate (to me) sounds just a little brighter.  But it's VERY subtle.

After around 1930, bare brass horns were lacquer coated.  Old lacquer doesn't seem to last that long so a 1935 lacquer horn may not have any left.

There is a difference.  It's VERY subtle.  You may hear it or you may not.  It's much less than the difference between a lacquer and a stripped horn.  The silver plate (to me) sounds just a little brighter.  But it's VERY subtle.

After around 1930, bare brass horns were lacquer coated.  Old lacquer doesn't seem to last that long so a 1935 lacquer horn may not have any left.