Hi Superfly.
Congratulations with your rare Slingerland copper on maple - drums. The series was called Concorde, and was produced only in ´72 - ´73.
Basicly we´re dealing with Slingys from their best period - but the copper plating - or what to call it - was not realy a succes: Adding a 1,2 mm thick genuine metal plate to the outside of a drum, does certaintly not increase the natural sustain of the drum, and that was - as far as I know - the reason why the Niles Guys stopped making the Concorde series in ´73. besides that, copper reacts instantly on oxygene and moisture, wich means that every little scratch in the protecting layer of laquer, that was sprayed on to them, has an evil tendense to develope into ugly black or dark green spots -- that is probably what has happened to yours, but I need to see some pictures to be certain. On top of that, it seams as if theese drums are more sensitive to changes in temperature, because that the copper plate can´t follow the ex/contractions of the wooden shell, and therefore slips/get loose.
Since we´re talking about a genuine copper plate, there is no problem in polishing away this patina, but then you need to polish down the entire drum, and have a pro painter to re-laquer it --- but then again; the problem returns with the first scratch.
When I restored my own Concordes, I chose to accept the fact that they have some ugly spots here and there, and that that´s just part of the drums history. The thought of recoating them never realy came to my mind
, not because it can´t be done, but because the true value of a vintage drum, lies hidden in its history.
Anyway, if you insist on removing the copper plating, make shure that you have a coupple of days off, and a - what to call it? - very good heat pistol --- but please don´t do it.
By the way. Does your 18" tom have 3 or 4 legs?
Good luck
Yours Carsten M