For work this thickness and over 24" (61 cm) in any direction Uroboros recommends using kilns with top, side and bottom heating.
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Firing Schedules (ramps are for 6" or larger open face firings on shelves) | ||||||||||||||
| Heating | Annealing & Cooling | ||||||||||||||
| Step 1 | Step 2 | Step 3* | Step 4 | Step 5 | Step 6 | Step 7 | |||||||||
| Target temps >> |
300° F 149° C |
1000° F 538° C |
To Desired Peak Temp (see Peak Temp Table) |
960° F 516° C |
775° F 413° C |
500° F 278° C |
75° F 42° C |
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| Maximum Thickness |
Ramp Rate (per hour) |
Hold (minutes) |
Ramp Rate (per hour) |
Hold (minutes) |
Ramp Rate (per hour) |
Hold (minutes) |
Ramp Rate (per hour) |
Hold (minutes) |
Ramp Rate (per hour) |
Hold (minutes) |
Ramp Rate (per hour) |
Hold (minutes) |
Ramp Rate (per hour) |
Hold (minutes) |
Minimum Total Time (hours) |
| 1" | 50° F | 40 | 50° F | 100 | 185° F | Per Peak Temp Table |
AFAP | 220 | 25° F | 0 | 45° F | 0 | 150° F | 0 | 49 |
| 25 mm | 28° C | 28° C | 103° C | 14° C | 25° C | 83° C | (2 days) | ||||||||
| 1.5" | 37° F | 60 | 37° F | 150 | 150° F | Per Peak Temp Table |
AFAP* | 360 | 12° F | 0 | 24° F | 0 | 75° F | 0 | 76 |
| 38 mm | 21° C | 21° C | 83° C | (6 hrs) | 6.7° C | 13° C | 42° C | (3.2 days) | |||||||
| 2" | 25° F | 80 | 25° F | 180 | 125° F | Per Peak Temp Table |
AFAP | 480 | 7° F | 0 | 14° F | 0 | 42° F | 0 | 115 |
| 51 mm | 14° C | 14° C | 69° C | (8 hrs) | 3.9° C | 7.8° C | 23° C | (4.8 days) | |||||||
| 3" | 18° F | 120 | 18° F | 225 | 100° F | Per Peak Temp Table |
AFAP | 720 | 3° F | 0 | 6° F | 0 | 18° F | 0 | 210 |
| 76 mm | 10° C | 10° C | 56° C | (12 hrs) | 1.7° C | 3.3° C | 10° C | (8.8 days) | |||||||
| 4" | 12° F | 160 | 12° F | 270 | 75° F | Per Peak Temp Table |
AFAP | 960 | 1.5° F | 300 | 3° F | 0 | 9° F | 0 | 379 |
| 102 mm | 6.7° C | 6.7° C | 42° C | (16 hrs) | 0.8° C | ( 5hrs) | 1.7° C | 5° C | (15.8 days) | ||||||
| 5" | 9° F | 200 | 9° F | 305 | 68° F | Per Peak Temp Table |
AFAP | 1200 | 1.2° F | 375 | 2.4° F | 60 | 7.2° F | 0 | 479 |
| 127 mm | 5° C | 5° C | 38° C | (20 hrs) | 0.7° C | (6.3 hrs) | 1.3° C | ( 1 hr) | 4° C | (20 days) | |||||
| 6" | 6° F | 240 | 6° F | 340 | 60° F | Per Peak Temp Table |
AFAP | 1440 | 0.8° F | 450 | 1.5° F | 150 | 4.5° F | 0 | 720 |
| 152 mm | 3.3° C | 3.3° C | 33° C | (24 hrs) | 0.4° C | (7.5 hrs) | 0.8° C | (2.5 hrs) | 2.5° C | (30 days) | |||||
| 7 | 4.5° F | 280 | 4.5° F | 375 | 55° F | Per Peak Temp Table |
AFAP | 1680 | 0.6° F | 525 | 1.2° F | 225 | 3.4° F | 0 | 934 |
| 178 mm | 2.5° C | 2.5° C | 31° C | (28 hrs) | 0.3° C | (8.8 hrs) | 0.7° C | (3.8 hrs) | 1.9° C | (38.9 days) | |||||
| 8" | 3° F | 320 | 3° F | 405 | 50° F | Per Peak Temp Table |
AFAP | 1920 | 0.4° F | 600 | 0.8° C | 300 | 2.4° F | 0 | 1366 |
| 203 mm | 2° C | 2° C | 28° C | (32 hrs) | 0.2° C | (10 hrs) | 0.4° C | (5 hrs) | 1.3° C | (56.9 days) | |||||
| Uroboros has no direct experience heating previously fired work in these thicknesses. These numbers are estimates only. | * For drop slumps cut Step 3 ramp rate in half or more | **AFAP means As Fast as Possible |
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| Basic Definition of firing steps | |
| Step 1 | Start heat up of prefired cold glass, shelf, mold, & kiln. Soak to distribute heat evenly |
| Step 2 | Heat prefired glass components to softening point Hold to distribute the heat evenly |
| Step 3 | Fire to desired peak temp Hold to desired finish |
| Step 4 | Lower to upper annealing point, dropping quickly to minimize devit Hold to distribute the heat evenly |
| Step 5 | Annealing ramp: cool to below the strain point Hold |
| Step 6 | 1st Cooling ramp Hold |
| Step 7 | 2nd Cooling ramp Open kiln when kiln interior is at room temperature. |
| Peak Temperature Table - Open Face Molds | |||
| This guide is intended as a starting point. Variations of 25° F (13.9° C) or more are expected for specific needs & circumstances, such as kiln type, rate of ramp-up, soak length, thickness of work or mold, etc. All other factors being equal, System 96 glass will require a peak temperature about 25° F (13.9° C) below Fusion FX 90 COE (Bullseye compatible) glass. | |||
| Activity | Temp F | Temp C | hold time |
| Bending (uni-directional) Shallow drop Slumping with molds Medium drop (sinks) 'Sugar' firing or Tack Fuse Pâte de Verre Fuse to stick |
1100° 1200° 1225° 1250° 1300° 1325° 1350°-1375° |
538° 649° 663° 677° 704° 718° 732°-745° |
1-20 mins 1-20 mins 1-30 mins 1-20 mins 1-20 mins 1-30 mins 10-45 mins |
| Maximum Temperature if under 1/4" thickness | |||
| Fuse flat with smooth edges Fill Bas-Relief molds - wavy edges Fill sharp mold details -irregular edges |
1420°-1450° 1450°-1475° 1475°-1500° |
771°-788° 788°-802° 802°-816° |
15-90 mins |
Revision 03/09