thanks. Not entirely sure I understand the intaglio process fully, bearing in mind a 'stone' wheel is used to create the cuts - it's not that I don't follow the basic principles, but it's understanding how such small dainty cuts, when finished, are bright and shiny bearing in mind they were made with a 'stone' wheel. Prior to acid polishing (c. 1920s), and in order to remove the grinding marks on bog standard cut glass, the cutters had to go back over every cut using a polishing compound, in order to brighten and polish the cut design. Acid polishing, apparently, did away with the need for this time consuming job, though in the process the sharpness of the cutting was lost to some extent. I can't imagine remotely that these very fine detailed intaglio designs might be re-worked to polish the cuts, and acid polishing would be out of the question. So the answer must lie in the method used for the basic cutting - perhaps the 'stones' are in fact ultra fine and capable of making and polishing the cuts first time round.
If you look at the picture in Hajdamach - p. 291 - there's a picture of Joshua Hodgetts at work on an intaglio lathe - albeit early C20 (much later than when the piece here was made) - and the 'stone' appears to be fed constantly with compound via the pad resting on the top of the 'wheel'.
If you look at 'rock crystal' cutting, this too has a similar appearance of fine detailed cuts that are 'watery' and shiny in appearance, so possibly the same method used - agree about re-reading all of this subject - it's complex.
Agree, the scimitar cuts (90 degree one side etc. ), are what we imagine typical intaglio to be, and there are a few on the piece here, though I'm also inclined to suspect that use of the word intaglio by glass cutters might just have been borrowed from the steel engravers. In the world of artist engraving on copper, steel zinc etc - i.e. resist - stylus for design - acid dip - clean
resist - ink up and print .... the end result is a fine intaglio line with which to print the ink. So perhaps it's possible that the glass guys borrowed the word 'intaglio' to describe their own fine detailed cutting. Well, it sounds good