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Seeley's Porcelain Slips
General Information:
For 50 years, dollmakers and porcelain artists have used Seeley's porcelain slip to create the world's most beautiful pieces. Artists know that when they start with Seeley's, they start with the best. That's because we use only the finest ingredients, and we test each batch of our porcelain slip to make sure it matches our exacting standards.
We manufacture our porcelain slip in upstate New York, using formulas we established after extensive testing by ceramic engineers and experienced artists. Our slip is thoroughly blended; then it undergoes a two-step filtration process to remove all impurities. Every batch of our porcelain slip is checked for viscosity and specific gravity, and we fire samples from every batch to make sure it meets our high standards.
Seeley's porcelain slip pours easily. It is strong in the greenware, it won't crack, even if left in molds overnight. An extended firing range makes for no-fault firing. Our slips fire to bisque that's free of specks and beautifully translucent.
Find out today why artists worldwide have made Seeley's porcelain slip their first choice. Call today for information and the store near you.
Casting Seeley' Porcelain Slip
1. Stir well.
2. Use slightly damp molds. Spray or "mist" the inside of the mold with distilled water to dampen.
3. Band mold tightly and pour slowly and steadily against one side of the pour hole. Pour the slip all the way to the top of the mold, then let it "shrink" a bit and top it off.
4. Check thickness of the casting at the pour hole to determine the right moment to drain.
5. After the slip has reached the desired thickness inside the mold, generally 1/8" (2-3mm) thick, empty it back into its container slowly and continuously.
6. Leave the mold with pour hole down for additional draining. If you do not have a pouring table, let the mold rest slightly tilted on a stick. The amount of time your leave the casting inside the mold varies, but in most cases, the casting can be taken out within 20-60 minutes.
7. If a mold won't release the casting, don't force it. Leave it in a little longer, then try again. Try lifting the back half of the mold first. Wait 5-10 minutes to give the greenware a chance to shrink further; then remove the other side of the mold. Let the back of the cast head or piece fall into your cupped hand. Don't wear jewelry or hand cream.
Soft firing bisque for Dust Free Cleaning
To clean your fired casting without producing dust, you should soft-fire your greenware to cone 018 (Approx. 1285ºF to 1386ºF, 697°C to 753°C). The Dust Free Cleaning technique considerably reduces health hazards in the handling of porcelain. (This technique is more fully explained in the Golden Key to Porcelain Dollmaking #GOLDKEY.) Kiln Sitter Operation:
Place a small cone 018 in the kiln sitter, set your kiln on Low, and fire with peepholes open for one hour. Turn the temperature up to Medium, with peepholes still open, until the kiln shuts off automatically.
Controller Operation:
Set your controller to increase in temperature at a rate of 500°F (260°C) per hour until it reaches 225°F - 275°F (107°C - 135°C). Hold for 1-2 hours, then increase temperature at a rate of 500°F (260°C) per hour to 1300°F - 1450°F (704°C - 788°C). Witness cone 018 touching shelf.
After the soft-fired ware is cool, submerge in water and clean it while it's wet - you won't have a speck of dust.
Bisque Firing
Kiln Sitter Operation: Fire on Low for 1-2 hours, peepholes open. Fire on Medium for 1-2 hours, peepholes open. (If pieces have been soft-fired, omit Low and start your kiln on Medium firing. Shut the lid and fire 1-2 hours. Then proceed to High.) Leave peepholes open. Set on High and fire until kiln sitter shuts kiln off.
Seeley's Colored porcelains (such as Seeley's French Bisque) and Bone White and Lady White
Cone firing: Use junior cone 6 in the kiln sitter. Use witness cones 5, 6, and 7 on the kiln shelf. After firing, cone 5 should be touching on the shelf, cone 6 should be bent to a 10 to 11 o'clock position and cone 7 should not have bent at all.
Controller firing: Set the controller to fire 500ºF (260°C) per hour to 2000ºF (1094°C). Then set controller to fire 100ºF (38°C) per hour to 2185ºF (1197°C). Final temperature range: 2170ºF to 2190ºF (1189ºC to 1200ºC).
Seeley's White porcelains
Cone firing: Use a junior cone 7 in the kiln sitter. Use witness cones 5, 6, and 7 on the shelf. After firing, cone 5 should be down hard, cone 6 should be bent from 10 o'clock position to touching the shelf, and cone 7 should have started to bend.
Controller firing: Set the controller to fire 500°F (260°C) per hour to 2000°F (1094°C). Then set the controller to fire 100°F (38°C) per hour to 2205°F (1208°C). Final temperature range is 2190°F to 2210°F (1200°C to 1210°C).
China Firing:
Kiln Sitter Operation: All paints fire to a witness cone 018 (junior cone 017 in sitter). Set your kiln on Medium for 15 minutes – 1/2 hour with peepholes open. Turn the temperature up to High until kiln shuts off automatically. Be sure to use witness cones to check firing.
Controller Operation: Set your controller to increase in temperature at a rate of 1000°F (538°C) per hour until 1350°F - 1425°F (732°C - 788°C). Leave peepholes open until shut off. Be sure to use witness cones to check firing.
The sitter cones and controller schedules used in firing your kiln will vary depending upon several variables: age of elements, condition of pyrometer and condition of thermocouple. Because of this, it is important to do test firings and keep a firing log to optimize your kiln firings and to get the best quality bisque possible.
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