Harrach Glass: System 96 Firing Schedules

Friday, June 29, 2012

Firing Guide


Firing Schedule:		Guidelines for firing projects up to 3/8-inch thick.
Slumping Schedule:
THICK Firing Schedules:		Guidelines for firing THICK projects ranging from 1/2-inch to 2-inches thick
Forming Chart:		Forming stages, definitions, and temperatures for firing System 96 products.
Bubble Squeeze:		Adding a stage during firing to reduce or eliminate bubbles
4-Segment Firing:		How to easily adapt our 6-segment programs to 4-segment controllers

Firing Chart (For projects up to 3/8" thick)

Segment	Rate	Temp	Hold
	(°F per Hour)	°F	(minutes)
1. Heating I:	300	1150	30
Moderate ramp up then hold to allow soft glass to settle. Soak even longer to reduce bubbles.
here is data
2. Heating II:	200	1370	20
Slow ramp to squeeze out trapped air.
here is data
3. Heat to Forming Stage:	400	See Forming Chart	Desired Effect
Heat glass to forming temperature. Consult Forming Chart.
here is data
4. Anneal I:	9999	950	60
Fast ramp down then hold to thoroughly equalize temperatures.
here is data
5. Anneal II:	150	800	10
Slow cool through sensitive zone, then hold to equalize.
here is data
6. Cool Down:	300	100	0
Moderate ramp down to minimize thermal shock.

Slumping Chart (For projects up to 3/8" thick)

Segment	Rate	Temp	Hold
	(°F per Hour)	°F	(minutes)
1. Heating I:	150	300	15
Slow ramp up to 300º then hold to equalize temperature of everything in kiln (minimizes thermal shock).
here is data
2. Heating II:	300	1100	20
Moderate ramp to 1100 and hold.
here is data
3. Heat to Forming Stage:	150	See Forming Chart	Desired Effect
Heat glass to forming temperature. Consult Forming Chart.
here is data
4. Anneal I:	400	950	60
Moderate ramp down then hold to thoroughly equalize temperatures.
here is data
5. Anneal II:	150	800	10
Slow cool through sensitive zone, then hold to equalize.
here is data
6. Cool Down:	300	100	0
Moderate ramp down to minimize thermal shock.

Forming Chart	Definition	Forming Temp
Slump	Glass softens and slumps to take the shape of a selected form or mold. Note: small molds may need higher temperatures and/or hold times.	1215º-1250º F
Tack Fuse	Separate glass layers are fused together with little deformation beyond softening of edges.	1350º- 1370º F
Contour Fuse	Separate glass layers are fused together, edges are soft and rounded, project surface retains the degree of dimesion desired by the artist (any degree beyond Tack but not yet Full fused).	1400º-1450º F
Full Fuse	Separate glass layers are completely fused into a single uniform layer, top surface is smooth and void of dimension or relief.	1460º-1480º F

4-Segment Firing
For faster firing: you may wish to accelerate or simplify firing for small or less consequential projects. If so, in the Fusing Chart, eliminate segments 2 and 6. In the Slumping Chart, eliminate segments 1 and 6.

Bubble Squeeze	To Reduce Bubbles Between Glass Layers
To reduce bubbles between glass layers, fire to encourage a very slow relaxing of the layers, “squeezing” air outward to the edges for release. As the fusing chart indicates, we recommend a lengthy hold at about 1150º F, then a slow ramp up to 1370º F. Increase the effectiveness of your “squeeze” by lengthening your Hold in Segment I and slowing your Rate in Segment 2. Bubbles are best avoided in the design stage. Large areas of uninterrupted layering invite them. For example, a 10 x 10-inch sheet atop another 10 x 10-inch sheet leaves no easy avenue of escape for the air between glass layers. Alternately, a 10 x 10-inch sheet topped with four 5 x 5-inch pieces provides seams to vent trapped air. Design to avoid bubbles for the best prevention.

Find this information and more on the System 96 web page.