This first question you should ask yourself is this "Am I repairing or
restoring?" The answer will make things clearer in your mind.
These are my two yardsticks, generally speaking.
If it's been found in a ditch & most of the paint has been removed by
abrasion, sun and rusting, then to repaint it is just part of the
restoration process. There is no "character" left to preserve.
If it has most of the original paint & just needs a good clean, then do just
that & when dry, rub it all over with an oily rag. Repairs & new bits only
add to the character of the device.
I am by no means consistent though & sometimes have a different approach. I
like bare satin finished aluminium and the ST flat twin is a case in point.
When I got it, it was devoid of paint & the chromate etching primer had
eaten into the surface.
I decided that I'd prepare it as a show engine, removed the barrels and
heads to look inside & finding all well, gloss blacked them. Using a number
of soft brass bristle brushes in a high speed drill, I then stripped off the
chromate primer, washed the engine down with meths & lacquered the ali
castings. I found traces of green paint inside the fan cover end caps and
carefully preserved this for some future restorer to discover.
It came to me without a mag, but I had just restored a circa 1920 EIC
magneto, complete with fabric covered HT leads. I also had a new matched
pair of mica insulated sparking plugs and one of those brass cylindrical
tanks from (I think) a mower. I chose these as they fitted the appearance
of the engine. In doing so, I temporarily emphasise the "early vintage" look
of the thing. Nothing irreversible. Here it is finished & mounted on a nice
100 year old rosewood stationery box I found for free in the club tent .
My mindset is that we only have these Iron Toys for a while & it is up to us
to at the least look after them, any restoration should be minimalist in
nature & follow the maker's scheme of painting if possible. If, like me, you
don't want to do the latter, then leave a witness for the bloke in our
future who will be following you down this rocky road in perhaps 100 years
time. Think doctor - and Do No Harm.
Make no mistake, for the great majority of the engines & driven devices
that fall within our perview, once they are cleaned up & cared for, they
will never be broken up for scrap now they are all beginning to appreciate.
Only giant machines that few can store or manage are in real danger & for
that we have Internal Fire and The Anson - and bloody good job too!