Technique Links

Glass Loading

Casting

Lifting

Cleaning

Grinding

Polishing

Testing

Integration

Shipping

Glass Loading Techniques

	Pieces of E6 low expansion borosilicate glass, typically 4-5 kg each, are made by the Ohara Corp. in Japan. The sand to make the glass comes from the beaches of Florida.
	Randy Lutz (left) and John Martin inspecting the E6 glass under polarized light in order to ensure its quality. The quality of the glass is very homogeneous with ~99% of each shipment accepted for each casting.
	Randy Lutz completing the installation of hexagonal cores or columns in the oven prior to loading glass for a 6.5-m mirror.
	The spin-casting oven is filled with an array of the hexagonal columns or cores, made of alumina silica. For an 8.4-m mirror, the casting array consists of some 1750 columns. Each column is roughly 20 cm in diameter and 80-110 cm high.
	Glen Weir, John Martin, and Randy Lutz loading E6 glass into the oven.
	Mirror Lab staff members are dwarfed by the size of the future mirror and the sheer quantity of glass: ~19.5 metric tons. The light-weight spun-cast mirrors weigh only ~15% of an equivalent solid mirror blank.
	At this point the oven is filled with glass. The next step is to assemble the oven walls and top (or hood), before the casting process begins.