釉式Yushiki

Enter a recipe and see its Seger formula, silica-to-alumina ratio, and position on the Stull chart instantly. Log firings and build a map of your own kiln.

Yushiki turns a glaze recipe into the numbers potters actually reason with. Type in your materials and amounts, and it instantly shows the Seger (unity) formula with the bases normalized to 1, the SiO2/Al2O3 ratio, and where the glaze lands on the Stull chart. Everything in the core app runs fully offline on your device.

Built for potters and ceramicists who mix their own glazes and want to understand what a recipe is doing, not just follow it.

CORE FEATURES (FREE, OFFLINE)

• Recipe to formula: enter materials and weights to get the Seger unity formula, silica-to-alumina ratio, and a live position on the Stull chart.
• Materials database: representative analyses are built in, and you can edit entries or add your own.
• Colorant reference: how iron, copper, cobalt and others develop across different addition levels, with oxidation vs. reduction differences and notes to watch for.
• Firing log: record firing date, cone/SK, atmosphere, your rating, photos and notes. Each logged firing adds a point to the Stull chart, so your records grow into a map of your own kiln over time.
• Complete backup: export and restore recipes, materials, experiments, firing logs, and photos in one archive.
• Sharing: share a recipe as text, or export a card image with the formula and chart included.

PRO FEATURES (SUBSCRIPTION)

• Reverse solver: work backward from a target formula to a set of material amounts.
• Experiment ledger and Next Experiment: saved line/triangle blends, kiln runs, test pieces, and small 3–5 test plans grounded in your own records.
• Recipe comparison: place recipes side by side to compare formula differences and thermal expansion.
• CSV and Japanese OCR import: read analysis tables or paper recipes and confirm every material and amount before saving.
• Material analysis versions: manage suppliers, lots, and analysis history.
• iCloud Sync: sync through your private Apple CloudKit database only after you explicitly turn it on.
• GPT review: submit a firing photo for analysis and suggestions for an adjusted recipe.

PRIVACY Your recipes, materials, firing logs and photos are stored on-device by default. A Pro subscriber can explicitly enable iCloud Sync, which also stores this app data in their private Apple CloudKit database. There is no account or sign-in, and no third-party analytics, tracking, or crash-reporting SDK. When you tap to generate a GPT review, a recipe-derived composition summary, up to one firing photo, and a StoreKit-signed transaction used to verify the Pro subscription are sent to the developer's Cloudflare Workers. The transaction is checked with Apple and is not sent to OpenAI; only the composition summary and optional photo are forwarded to OpenAI. The app does no cross-app or cross-site tracking.

Thermal-expansion estimates and AI insights are meant as relative guides for comparing recipes, not guaranteed absolute values. Actual firing results vary with your materials, clay body, and firing conditions.

SUPPORTED DEVICES iPhone / iPad (iOS 17+ / iPadOS 17+). The interface can be switched between Japanese and English in-app (technical data such as raw-material names remains in Japanese).

SUBSCRIPTION Yushiki Pro is available as a monthly subscription at 400 yen or a yearly subscription at 3,000 yen, each with a 7-day free trial. Subscriptions renew automatically unless auto-renew is turned off at least 24 hours before the end of the current period. You can manage or cancel your subscription in your App Store account settings after purchase.

TERMS OF USE (EULA) Subscriptions are subject to Apple's standard Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/