by Peter W. Wed Mar 29, 2017 11:25 am
I am going to throw something up in the air (pun intended as you read on) developed from years of restoring vintage radios and legacy audio equipment.
a) there is nothing magical about painting - even hammertone paints these days are remarkably easy to use.
b) Things do not have to be on the ground (on a solid surface) for painting.
c) Several light coats are typically infinitely better than one heavy coat - unless protection is the sole and only purpose (High-zinc or rust-proofing paints, for example).
So, if it is possible to hang the item to be coated up in the air - if one has the correct location for this - then coatings may be applied from all sides and all directions directly perpendicular to the surface to be coated, the ideal process.
If there are machine-screw ends available, I will use a nut of the correct size on the end of that screw for suspension. If there are flange holes - I will use mono-filament fishing line, very thin for its strength and does not hold paint or stick.
There are all sorts of nifty means to mask things. several coats of rubber cement will protect a surface, then may be rubbed off with a finger after the coating cures. Painter's blue tape. soft rubber gasket material may be jammed in the bell holes to prevent material from getting up inside the transformer - if the bells are to be left in place.
But it is nice not to have any blind (uncoated) areas on anything - as the nature of corrosion, is such that it will inevitably start at such a transition as any galvanic action will be concentrated at such transitions (another reason not to add 'third wires' on devices not designed against them - do I need to explain why?).
For the same reason, I would also suggest that if end-bells are to be coated, that the inside also be coated. Not that we expect that our amps will be subject to damp locations, salt air or the like - but it is nice to have one less worry.