Apparatus and method for heat treating a glass substrate

A method of heat treating a plurality of glass substrates in a furnace comprising:

• positioning at least one spacing member between pairs of adjacent glass substrates of the plurality of glass substrates, the at least one spacing member comprising a closed outer frame portion bounding an open interior, and wherein a difference between a CTE of the one or more spacing members and a CTE of the plurality of glass substrates is less than 10×10−7/° C.;
• supporting the plurality of glass substrates on a support platform in the furnace in a substantially vertical orientation, the supporting comprising;
• contacting a first outermost most glass substrate of the plurality of glass substrates with a first plurality of restraining pins, each restraining pin of the first plurality of restraining pins being rigidly fixed;
• contacting a second outermost glass substrate of the plurality of glass substrates with a second plurality of restraining pins, wherein each restraining pin of the second plurality of restraining pins being movable along a longitudinal axis thereof, and wherein each restraining pin of the second plurality of restraining pins applies a force to the second outermost glass substrate;
• heating the plurality of glass substrates in the furnace;
• cooling the plurality of glass substrates;
• and
• wherein an out-of-plane distortion of the plurality of glass substrates after cooling does not exceed 100 μm.