I'll toot out the "my wife the conservator" line again and say that in their lab they regularly used a variety of products including Autosol (a German brand which is widely available - at least here) and Dura-Glit. The latter is kind of nice because the polish and solvent are in a cotton wadding - which can be pulled off in small pieces and used as is or wrapped on the end of wooden skewer (a-la-a Q-tip) for more delicate work. Always remember to wash off any residual polish as the acids in some of them will keep "working" on the metal - a mild detergent or even just clean water works.
For those interested, I have just ordered a set of disposable "microbrush" applicators from Lee Valley Tools ($8.95CDN for a set of 40 - 4 different types 83K09.25). Not sure what they will be used for yet but couldn't resist. They also have a "precision oiler pen" for $8.50CDN (25K70.02). Lee Valley is one of my favourite stores here in Ottawa! :-)
Paul Williams,
Ottawa, ON, Canada