Smiths floating balance clock

[HectorLooi]

I finally managed to get my hands on a floating balance clock. It arrived on Christmas eve but I didn't open it until after New Year, just in case there were any Covid-19 variant virus stowed away on the packaging. 

The clock is running and the chime is working. The clock case is in decent condition for its age but someone had applied a horrible layer of shellac over the original finish. The clock is running about 8 minutes slow a day, even with the regulator turned all the way to the right.

The movement inside also had the horrible shellac treatment done to it. Even the balance was not spared. All the Smiths floating balances I see on YouTube are a metallic grey, but this one is speckled with shellac. 

I don't know what's the best way to remove the shellac without damaging the balance. Can anyone advise me before I try soaking it in alcohol. 

[AndyHull]

Assuming it is shellac, and assuming that it is not a thick layer, then perhaps brushing it with alcohol on a small paint brush rather than soaking it might be a better way of removing it.

From the description it could be that someone sprayed it with a rattle can of acryllic clear coat, which may or may not be removed by alcohol. Try some your solvent on an area that isn't too important. Clear coat might require something more aggressive like acetone to remove it.

[wls1971]

Shellac Lacquers are made by dissolving it into methylated spirits and is easy to remove from metal by using it use a cotton bud with not too much on. Spray on Lacquer depending on formulation can be removed with acetone or Xylene thinners some Lacquers are impervious to acetone and some are impervious to Xylene so it trial and error.

[HectorLooi]

Andy might be correct. It might not be shellac but some kind of lacquer or varnish. I managed to get a lot of it off by dipping it in denatured alcohol and brushing it with a bristle brush. But it doesn't seem to be dissolving in the alcohol. I'll try xylene and acetone tomorrow. 

I just can't believe someone could spray lacquer on a balance wheel and even on the balance spring. 

[KarlvonKoln]

I can believe it.  I have been cleaning out an old Elgin #92 pocket watch where some former owner coated the movement with Cosmoline, even behind the dial too!

Never know what you're going to find sometimes. 

[AndyHull]

If the item wasn't working, then whoever owned it may simply have used it as a display piece, and in order to make it look its best (to their eye) they gave it a "nice shiny coat" of whatever inappropriate finish they had to hand.

The uniform nature of it makes me think it probably came out of a rattle can, in which case xylene (dimethylbenzene) or even something like butanone, also known as methyl ethyl ketone (MEK) might be necessary to dissolve it. All of the solvents I've suggested should be used in a well ventilated area. Also... wear gloves.

[HectorLooi]

I was studying the regulator last night. There doesn't seem to be any weights moving radially when the regulator is rotated. Is my balance missing any parts or broken?