Hi Ignator,
Back in the 1970s I did a job where I was using old motor windings to make a solenoid switch... where a gap in the magnetic loop between input and output of a transformer made the output voltage vary ... but that aside, I was re-insulating wiring soldered joints with shellac. The lacquer used for the original winding "enamel" insulation from the old transformer.
Now Shellac is an organic lacquer, that becomes dissolved into a liquid in alcohol... So washing windings in alcohol is NOT a good idea, in case you wash away some insulation and it is then thinner than planned.... so fails at a lower voltage than the designer intended...
I suggest you test (or get a PROPER electrician to test) the insulation resistance of your windings using a 1000V Mega tester. NOT an AVO meter. It is the only (simple) way to be sure the windings will not suddenly blow-up, when HOT and a small voltage spike hits the windings.
Any electricians help me on this? - NOT my trade, just what the proper electrician told me when I was doing a job...
K2