# Tidal Ceramic — press proof 02

Tidal Ceramic is a palm-sized positive master and a digital clay mockup. The master, plaster mould, clay pull, surface finishes and firing have yet to be tested physically.

## From painting to relief

The relief follows the oval within the photograph of Iana Kochu’s *Tidal Oval*, using the rectangle from approximately (476, 165) to (986, 935) in the 1600 × 1067 source. This removes the fabric and wooden surround. The hand-traced paths retain the inward curl of the rose and its thicker lower end, the negative blush channel, the pale blue outer rim and the deep cobalt sweep. The gold-coloured accent stays on the short seam near the base of the curl. [Source photograph](../../assets/tidal-oval.jpg).

The earlier Tidal Ceramic image concept informed the matte clay and shallow edge treatment. The SVG records the new composition and its height assignments in the source photograph’s coordinate system. The reference file in the repository is `docs/kochu-studio/prototypes/visual-studies-2026-11-01/tidal-ceramic/result.png`. [Editable motif](motif.svg).

| Land | Height above the print bed |
| --- | ---: |
| Sea-green, blush and lower diagonal | 4.1 mm |
| Warm diagonal, blue rim and inner stream | 5.9 mm |
| Rose curl | 7.8 mm |

## Master and first pull

The positive is **76 × 114 × 7.8 mm**. Import it as millimetres, with relief facing **+Z** and the flat back on the print bed at **Z = 0**. The height map and tapered perimeter form one connected volume. The broader base is the mouth of the mould. Hold the negative fixed and withdraw the positive along **−Z**, perpendicular to the back. The same withdrawal direction applies to the clay while the mould is held in that coordinate system. The measured minimum is **6.60°** from that axis on the lower perimeter wall and **4.23°** across the full upper surface, including the rounded shoulder. [Positive master STL](tidal-master.stl) · [Mesh checks](verification.json).

1. **Print the positive.** Begin by trying a 0.16–0.20 mm FDM layer height with the broad face on the bed and the relief uppermost. In ideal geometry each higher section sits over the one below. Check the slicer’s layers and verify that the printed edge has no elephant’s foot or stray burrs before casting. Sand and seal the relief if needed. Try the intended sealant and release system on a small print offcut before using them on the master.
2. **Cast a one-part plaster negative.** Fix the flat back to a leakproof board, build a dam around the positive and leave roughly 20 mm beside it and above the crown for the first trial. Use a compatible release on the sealed master, then pour pottery plaster using its supplier’s instructions and safety data sheet. Once the plaster has set and cooled, remove the board and withdraw the master straight along the mould axis. Let the plaster dry completely before pressing. [Seattle Pottery Supply’s mixing and drying instructions](https://seattlepotterysupply.com/pages/instructions-for-mixing-plaster).
3. **Make one clay pull.** Press a soft, even slab into the dry cavity, working from the deep curl out to the rim. Level the rear at the mould opening and trim the edge. Once the clay has firmed enough to hold its shape, invert the mould onto a flat board and ease it away along the axis. Inspect the first pull for rim tears, bubbles, retained layer marks and plaster chips. [Dave Finkelnburg on plaster press moulds and pop-outs](https://ceramicartsnetwork.org/ceramics-monthly/ceramics-monthly-article/Techno-File-Plaster-Pop-Outs).
4. **Test colour and shrinkage.** Try the rose and blue as slips or underglazes on test tiles for the chosen body and firing schedule. Record shrinkage and any warping from the first pull. The mesh measures the unfired target at full scale and the browser colours are a finish study.

The print bed, draft and topology checks use the delivered binary STL. Actual layer adhesion, fit, sealant compatibility, plaster release, clay shrinkage and fired colour depend on the materials and equipment used.

## Reproduce the proof

From this directory, `python3 build-master.py` regenerates the STL from the height paths in `motif.svg`. Use `python3 build-master.py --inspect` to check the binary STL without rebuilding it. The inspector verifies the closed, consistently wound manifold, the vertex fans and the flat contact area. The convex footprint and nested sampled rings partition XY without overlaps. Every non-base triangle faces upwards in its XY projection, so a ray parallel to Z meets one relief surface and the flat base.

Serve the Kochu Studio static prototype with `python3 ../../serve.py`. Run `node verify-and-capture.mjs` from this directory with the workspace’s existing Playwright and Chromium. Set `KOCHU_BROWSER_EXECUTABLE` to the executable path to use an installed Chrome, or `KOCHU_PREVIEW_URL` to point at a different preview server. Add `--capture` to replace the two art-only PNGs with fresh 1200 × 900 oblique views from the viewer and update the browser report. The clay and printed-master views both load the actual STL, with different simulated surface finishes.

[Clay render](cover.png) · [Master render](master.png) · [Browser and topology report](verification.json).