Ceramics
Notes
- Fine Detail
- Strikingly precise
- wears away quickly - like in fewer than a dozen castings. (GPT says 30 - 50 castings)
- This supports the 3 step mold:
- 3D Print (costly, time consuming, high precision, master)
- Silicone or Urethane mold (cheaper, rubbery / durable)
- Plaster mold (good for 20 shots, cheap)
- You could hit a rhythm of creating a new plaster mold every day, with 20 active molds at a time and a 24 hour pull cycle.
- Porosity of the bisque is critical for underglaze adhesion.
- Fire on the low end of cone 06 - 04?
- Don't get the surface dirty.
Links
- https://old.reddit.com/r/Ceramics/
- Kiln_Controller
- Making Casting Slip: https://www.youtube.com/watch?v=9I3XE3D6Nqs
- Clay and Water to Thick Oatmeal (200 parts dry clay, 50 parts water, ballpark)
- Mix in 4 parts Sodium Silicate and 1 part soda ash until half-and-half consistency.
- The Competition: https://www.youtube.com/watch?v=2JWwIpmHLO8
- Production Moldmaking: https://www.youtube.com/watch?v=5rUq9m_mIW8
- Slip Chemistry : https://www.youtube.com/watch?v=dmj7XiOd1K4
- Color Inspiration: https://old.reddit.com/r/Ceramics/comments/19d754y/so_happy_with_my_most_recent_round_of_pieces_and/
- Motawi Tile: https://www.youtube.com/watch?v=lv4ITBL70nQ
- Pinstripe Underglaze: https://old.reddit.com/r/Ceramics/comments/19d754y/so_happy_with_my_most_recent_round_of_pieces_and/
- Slipcasted Bowls: https://old.reddit.com/r/Ceramics/comments/12zk9um/a_few_of_my_cute_slipcasted_bowls/
- This isn't a faux fountain: https://old.reddit.com/r/Ceramics/comments/16k9yjx/trinket_or_jewelry_dish_with_melted_glass/
- Laguna Kiln Furniture
- Marjon Supply: https://marjonceramics.com/
- Low, Mid, High: https://thepotterywheel.com/low-fire-vs-high-fire-clay/
- Finding a Firing Service: https://thepotterywheel.com/10-easy-ways-to-find-a-pottery-firing-service-near-me/
- Formulating Porcelain: https://www.digitalfire.com/article/formulating+a+porcelain
- Mechanics of Ceramics: https://www.youtube.com/watch?v=llxiBmKNZSI
- Flexural Strength: https://en.wikipedia.org/wiki/Flexural_strength
Recipes
Plaster
- 1 Liter of Mold
- 1 Kilo of Dry #1 Pottery Plaster
- 0.7 Liters (kilos) of Water
- slake 3 minutes
- stir
- For 5 minutes?
- until uniform, as little as possible?
Slip
- 1.75 specific gravity
- Have tried as low as 1.7, which I like. Update: maybe a bit too thin, though I do like the slight castings it produces.
- Have tried as high as 1.85, which is too thick for me.
- Seems to effect the thickness of the casting - more so than does the dwell time before pouring off.
- too much deflocculant = gels quickly
- Just right = gels eventually, like hours
- OK - never gels but very liquidy
- recipe 1
- 40 fl oz thick oatmeal clay
- 12 ml sodium silicate solution
- 1/4 tsp soda ash (dissolved in a tablespoon of water)
- barium carbonate to capture salts
- sodium ash to dissolve lignite (small)
- filter to remove large lignite
Slips
Slipcasting requires a smooth, fluid slip (a liquid clay mixture) that can flow easily into molds and create thin, even walls as it dries. The characteristics of the clay for slipcasting are different from those for hand-building or throwing, especially in terms of plasticity and particle size.
Key Differences for Slipcasting:
- Deflocculants: Slipcasting requires the addition of a deflocculant, which helps the clay particles in the slip stay suspended in water without becoming too thick or requiring too much water. This allows for a smooth, pourable consistency while keeping the water content low, leading to faster drying and less shrinkage.
- Common deflocculants include Sodium Silicate and Soda Ash.
- Clay Body Adjustments: The clay mixture should be smooth and free of coarse particles (like grog) to allow the slip to flow easily and create detailed, thin-walled castings.
Here’s how the recipes would change for slipcasting:
Slipcasting Recipes:
1. Basic Earthenware Slipcasting Recipe (low-fire):
- 50% Ball Clay (OM4 or similar, for plasticity)
- 25% Kaolin (EPK, for whiteness and smoothness)
- 25% Talc (acts as a flux at low temperatures, helps reduce shrinkage)
- Add: Deflocculant (e.g., 0.25% Sodium Silicate and 0.1% Soda Ash, added to water before mixing)
2. Basic Stoneware Slipcasting Recipe (mid to high-fire):
- 40% Ball Clay (for plasticity)
- 30% Kaolin (for smoothness and whiteness)
- 20% Feldspar (for fluxing and vitrification)
- 10% Silica (for strength and reducing shrinkage)
- Add: Deflocculant (as above, Sodium Silicate and Soda Ash)
3. Basic Porcelain Slipcasting Recipe (high-fire):
- 50% Kaolin (EPK or Grolleg, for whiteness and smoothness)
- 25% Ball Clay (for plasticity)
- 25% Feldspar (for fluxing and vitrification)
- Add: Deflocculant (same as above)
Important Considerations:
- Particle Size: For slipcasting, you’ll want to use finer mesh clays and other materials (usually 200 mesh or finer) to ensure that your slip flows smoothly and evenly into the mold. This is especially important for porcelain slip.
- Water Content: The exact water-to-clay ratio can vary depending on the materials, but generally, slipcasting slips contain about 40-45% water. The deflocculants help reduce the amount of water needed while keeping the slip pourable.
- Testing the Slip: Once you’ve mixed your slip, you should test its viscosity and adjust with water or more deflocculant to ensure it flows smoothly into molds and releases cleanly.
With these modifications, you’ll have slipcasting-specific versions of earthenware, stoneware, and porcelain that are tailored for optimal performance in molds.
