So if the magnet sticks, then I’m good to remove the varnish, but if it sticks, don’t do it? (Sorry to ask) xThanks! I am not entirely sure and hope others will chime in, but on very early (and perhaps very new vintage) bags parts of the hardware may have been plated. If you hold a magnet to it, it shouldn't stick on solid brass. It didn't on mine, so I knew it was safe to take the whole varnish off.