Category:Ceramics

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Notes

  • Calibration
    • Cone 04 = 1700, 3600 seconds soak
  • Batch Weights
    • 2024-12-01: 1.83 gravity
    • 2024-12-12: 1.75 gravity, 90 minutes, good
    • 2024-12-13: Amaco celadon glaze 1.35 gravity good for pouring and spraying.
      • Speedball mid-fire seems a bit thick at 1.35, but need to confirm
  • 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.
  • Slip / Engobe Thixotropy, Flocculant, Viscosity, Gravity
  • Mug Dimensions
    • Basic: 80mm wide, 100mm tall, 30mm inside the handle, 6mm thick walls and handle
  • Photon Mono M3 Max Volume: 11.8"H x 11.7" x 6.5"
  • Image Stamping
    • Vector Image
    • High Res Black & White Raster
    • Gaussian Blur at 4 or 5 minimum
    • Plane, UV Map
    • Subdivision
    • Displace (UV, Texture, strength = 0.0005)
    • Deform -> Curve
    • Decimate (if desired)
    • Frame to appropriate # vertices
      • TODO: Process for this. It's not too painful for now to go manual.

Links

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?
  • Cure for 1 hour before demolding

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:

  1. 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.
  2. 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.


Clay Ingredients

Core Dry Materials for a Basic Kit:

  1. Ball Clay:
    • Used in nearly all types of clay bodies to improve plasticity and workability.
    • Common in stoneware and porcelain recipes.
    • A good starting option: OM4 Ball Clay from Laguna.
  2. Kaolin (China Clay):
    • A primary clay in porcelain for its whiteness and strength at high temperatures.
    • Gives porcelain its fine-grain texture.
    • A recommended type: EPK Kaolin or Grolleg Kaolin.
  3. Fire Clay:
    • Used in stoneware bodies to improve durability and resistance to high temperatures.
    • Adds a coarser texture but good for structural strength.
    • Suggested option: Lincoln Fire Clay or Hawthorn Fire Clay.
  4. Feldspar:
    • Acts as a flux, lowering the melting point of other materials.
    • Essential in all types of clay to improve vitrification (glaze adherence and water absorption).
    • A good option: Custer Feldspar or Minspar 200.
  5. Silica (Flint):
    • Adds strength and reduces shrinkage, critical for porcelain and stoneware.
    • Helps with the thermal expansion of the clay body.
    • Common option: 325 Mesh Silica.
  6. Grog (for stoneware and earthenware):
    • Pre-fired and ground-up clay that adds texture and reduces shrinkage in high-fired clays.
    • Provides additional structure and can affect aesthetics with texture.
    • Various mesh sizes are available depending on the texture you want.

Additional Components for Exploration:

  1. Bentonite:
    • A small amount (1-3%) can improve plasticity, especially in porcelain bodies.
    • Use this for workability if your mix feels stiff or lacks elasticity.
  2. Nepheline Syenite:
    • A flux that can replace some feldspar in stoneware and porcelain, giving a smoother finish.
    • Lowers the firing temperature slightly.
  3. Talc:
    • Used in low-fire earthenware bodies, particularly for its fluxing properties.
    • Helps achieve a smooth texture.
  4. Vermiculite or Perlite:
    • For adding insulation properties in larger sculptural pieces or functional ware where strength and thermal shock resistance are important.
  5. Colorants (optional but good for aesthetic testing):
    • Iron Oxide: For a range of reds and browns in earthenware.
    • Cobalt Carbonate: For blue tints.
    • Manganese Dioxide: For deep browns and black tones.

Images

  • Production-mold-making.jpg
  • Conechart.jpg

Subcategories

This category has only the following subcategory.

C

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