I have toenails thicker than 2/3 mm, that's nothing! However, it should have worked by now... I hope the bottle will soon be clean. Bugger all if I know how...
I don't suppose there's any way you could get us a pic or two of this most frustratingly stubborn paint.. is there? There MUST be a way to dissolve it.. unless it was kiln-fired into the glass or something..
i could use it (baking soda + vinegar) to rub off remaining paint, rather than cif (or vim) in the US/canada. Which would be gentler/less abrasive you reckon?
Those are caused by impact with another hard surface, probably with the embossing of a few fellow coke bottles.. it's way too difficult for me to explain, I'm just a painter.. but you have paint literally trapped under glass in those crescent cravasses.. I bet in real size it doesn't look that bad, does it?
Here's a close-up. Doesn't look like impact, just the tiniest circular etchings lower left, and larger ones top right, with the slivers of paint embedded in the outer borders. Looking through a 4X loupe the paint is not trapped under the glass, definitely on the surface. It's coming off slowly through gently rubbing/polishing using CIF cleaner and cotton buds.