Removing paint from frosted glass lampshades

[Chip]

A friend of mine has some 1930s frosted glass embossed lampshades, basically minute detail with frosting added in.

Someone has in the past decided that painting them was a good idea...

She's tried pretty much all the 'gentle methods' (elbow grease, hot water, soap, etc.) to remove the offending paint (appears oil based) but has been very reticent about using anything stronger.

Does anyone have any 'handy hints', and would caustic soda be a bad idea or a good one? I regularly use it on plastic phones for paint removal but wasn't sure if there might be something other than 'plain glass' in the lampshades. Also she suggested Nitromors or an equivalent, but if caustic soda would work I'd try that first as it's cheaper and disposal is easier.

We're fairly certain the paint dates from the 80s so should be lead free.

[Stuart Noble]

Caustic should be ok if it's oil based paint. Washing soda often works just as well, and is easier to handle. AFAIK neither has any effect on glass or metal (apart from aluminium). If it's an acrylic paint, a water washable Nitromors type remover

[Fred]

Caustic soda does etch glass though very slowly so should be OK particularly if the glass is already frosted.

My first choice would be Nitromors or similar.

[Andy Dingley]

These aren't just glass are they, there will be some framing metalwork involved?

So stay away from the caustics and go straight for an organic solvent. Water-washable Nitromors or equivalent, and a plastic scraper.