Powerful magnets are used to temporarily reduce the ball diameter by 105, not a lot, but just enough. Assembly is carried out under weak green or red light, then the assembled races are exposed to a bright flash of blue/white light. For about three minutes the races 'plink' like metallic popcorn. Around 0.01% of races are rejects because one or more balls don't expand, or distort and these have to be detected These days the process can be fully automated, but in parts of Tibet the process is farmed out as a cottage industry as the tinkling of the races resembles small cymbals or wind chimes and is considered to propriate good fortune. This necessitate thr movement of large quantities of balls in light-sealed containers into remote rural areas, not a big hazard these days when a Toyota Landcruiser or similar is available, but in the 70s and 80s Musk oxen were used along with fabric covered baskets. This meant the balls could only be moved safely at nights with no more thana new moon showing, a risk process for all the obvious reasons.
Neil
Edited By Neil Wyatt on 27/05/2016 10:46:09