Not sure to what extent this 'grinding' - to produce basic and crude decoration - was used in the U.K. in the C19 - it is used as we know as a preparation in the process of cutting, but I'm struggling to see it as a method used to produce a frosted surface as shown on this decanter - for obvious reasons grinding wheels generally are coarse in texture, and if the glass has to be further processed to smooth out those coarse marks then as a process, efficiency would be lost. Additionally, the need to maintain a perfectly smoothly curved surface - avoiding flats - would be at risk if held up to a grinding wheel. Prodigious amounts of drinking related wares - in the C19 in the U.K. - were decorated using a copper engraving wheel, and I'd suggest most of the 'fern' (pteridomania) cutting, seen on drinking glasses etc. were so decorated - the final appearance is similar to that shown by Cagney, but the result is much finer. This multiple repeat 'slightly curved and arching' shape was a staple decorative motif used by the wheel engravers, presumably replicating some sort of floral motif. Should we dismiss the possibility of the frosting on this piece having been the result of machine acid etching, especially if the area to be treated - as with this example - is geometrically easy to produce, and not some very detailed intricate image? Might needle work, etched through the resist, produce very fine directional marks? Acid appears to have been used commonly in the C19, with health hazards ignored, and the benefit of producing very fine results in the way of smoothness etc. would not have been an opportunity they might have ignored. How was the Greek Key produced here - engraved or acid etched?