In April 2000 I (Barry Kahn of Caravan Beads) visited the Miyuki glass bead factory in Japan. My tour was fascinating and the information below is what I gleaned from touring the factory. I was not invited to photograph most of the process, sorry. -bk
How Miyuki Glass Seed Beads Are Made
Step One: Raw materials and recycled glass of the same color are mixed and melted in the furnaces. The Miyuki factory has both automatic and manual furnaces operating 24 hours per day. They are on the 2nd floor.
Step Two: When ready, molten glass from the furnaces falls through a hole. The shape of the hole determines the shape of the glass tubes. Compressed air hitting the center of the glass column turns it into a hollow tube of glass.
Step Three: After dropping to the first floor, the vertical tube of falling glass passes under a thick chunk of wood and turns at a right angle to become horizontal. Imagine a vertical length of rope passing under a pulley and then being pulled sideways. The scene in the glass factory is much more dramatic, however. For starters, the glass "rope" is still extremely hot so that it is slowly burning its way through the smoking piece of wood. In addition the tube of glass is actually being pulled over a series of metal troughs by a machine which not only pulls the glass but also cuts it into one meter lengths. The speed of the pulling determines the diameter of the glass tubes. A faster pull makes thinner tubes; a slower speed makes them thicker.
Step Four: The cooled tubes are sorted to make sure that they are the correct diameter for the size beads being produced. Any tubes which are not the correct size will be recycled and remelted to make new glass.
Step Five: The tubes are cut into beads. As the cutting room is not open to any outsiders, I can't offer further information. I did learn that one Delica cutting machine can only cut 4-5 kgs per day, which is one reason for their high cost. (And contrary to some rumors, Miyuki cannot run the Delica cutting machines faster to keep up with increased demand, with an accompanying decline in quality. Instead high demand just leads to longer waits for production). Delicas are not cut by lasers, by the way, another occasional rumor.
Step Six: Cut beads are mixed with carbon black and reheated to make them round. Delicas are only slightly heated; round beads are heated more.
Step Seven: The beads are washed. Miyuki has their own on-site water treatment equipment.
Step Eight: The beads are heated again to give them a surface polish. Basic opaque and transparent beads are now finished and ready to pack.
Step Nine: Fancier beads (AB colors, silver and color-lined, metallic, etc.) are based on the basic opaque and transparent colors. There are several different locations in the factory where dyes and other coatings are applied. Some beads require multiple treatments which directly influence their final cost. After dyeing or color-lining beads, Miyuki reheats them again to "set" the colors, a step skipped by some bead companies to reduce costs.
Caravan Beads and Barry KahnCopyright note: This information is copyright 1996-1999 by Caravan Beads, Inc. It may be freely printed, copied, and distributed electronically IN ITS ENTIRETY. Please--no quotes out of context. Any errors, typos, etc. are the fault of Caravan Beads, Inc. and should be brought to our attention--thanks! Feel free to post it on the appropriate bead sites on AOL, Prodigy, Compuserve, etc.