Restoration of a Standard Folding Typewriter - stripping lacquer off aluminum

The full re-build of the little Corona 3 was actually done as a trial-run for the possible full re-build and restoration of my Standard Folding Typewriter. This relatively rare machine carried much history with it, signs of repairs and use over its lifetime. It however also looked 'derelict' and frankly it is/was. Being a bit daunted by the machine, it'd been kept wrapped (dirty!) on a shelf since getting it in 2022.

The Corona 3 proving to be feasible, the Standard Folding was now decided to get a full re-build. This will make it look better, cleaner and perhaps even functional. (And not looking like you'd catch something off it at 6 yards probably also would enhance its chances of surviving.)

The crinkle paint probably was applied in the 1930s, so historical of itself already. This had however to be completely removed for a restoration. All screws had been painted-over and impossible to remove, and also of course because these machines should be plain, dull aluminum.

Stripping paint from aluminum cannot be done with the usual method of lye; this would destroy the aluminum part (and potentially be quite dangerous too)! An alternative method is then acetone; especially older lacquer should dissolve and/or soften with acetone (i.e. nail-polish remover).

Because acetone is very volatile, a lidded bin was used and a few liters of acetone bought. Some paper painters-tape to better seal the lid and then propped-up to allow 'dunking' of the painted frame.

Note that also the celluloid top-layer of the old keys will react with the acetone. As these were not original and going to be replaced anyways; these were left on the machine. (And also because all screws were painted-over solid and couldn't be taken off.) 

The acetone-method does work, but needs much more time than the lye-method. Only after two full days in the acetone-bath was this lacquer fully softened.

After leaving it in acetone for 48 hours, the machine still looked painted black as before. The lacquer on the frame had by then however completely softened to a 'paste' - it could be simply wiped off with tissue-paper or a soft brush.

After wiping-off the black goo, fortunately most of the frame's original passivated-aluminum finish came out fine. Unfortunately, the front-panel and the carriage-panel did not come out so well, these ended up having to be polished and are now plain, shiny aluminum - to be dealt with later.

Importantly: all screws are released from their lacquer-seal and the little machine can now be taken fully apart for cleaning and re-building!