| 摘要 |
To obtain recessed, one-piece glasses of high quality, especially as regards the polishing of the recessed inside face, there are prepared separately, on the one hand, a blank which will constitute the back of the recessed glass and, on the other hand, a ring with appropriate contour and appropriate thickness for forming its skirt. These two pieces are next polished at least on the face pointing towards the recess side, where the back is concerned, and on the part to be welded, where the ring is concerned. Finally, the two pieces are assembled by hot-welding.
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