Tareline

Mix by weight, not by eye.

Tareline is a weight-based calculator for two-part coating mixes (built for Cerakote, works for any base + hardener that mixes by a fixed ratio). It replaces graduated cylinders with a disposable cup on a scale:

1. Put the empty cup and liner on the scale and press tare.
2. Pour the base ("paint") and read the weight.
3. Enter that weight; Tareline gives you the target total to add hardener up to.

That target is the only number the operator has to watch — no meniscus reading, no second measurement, no bad batches.

The math

Ratio R:1 means R parts base to 1 part hardener, by weight.

hardener = paint / R
total    = paint + hardener   →   the number the scale should read when done

This mirrors the original spreadsheet exactly (Hardener = Paint / Ratio, Total = Paint + Hardener). The logic lives in one small, unit-tested module: app/src/lib/mix.ts.

Repository layout

tareline/
├── app/    Expo (React Native) mobile app — the calculator
└── web/    Static landing page (deploys to Cloudflare Pages)

Tech stack

Piece	Version
Expo SDK	57
React Native	0.86
React	19.2
TypeScript	6
Tests	jest-expo

Quick start

Mobile app

cd app
npm install
npm start          # scan the QR with Expo Go, or press a/i/w
npm test           # run the math unit tests
npm run typecheck  # tsc --noEmit

Landing page

cd web
npx serve .        # or open index.html directly — it's a single static file

Deploying

• App — build with EAS Build (npx eas build) for the App Store / Play Store, or run as a PWA via npx expo export --platform web.
• Landing page — web/ is static; deploy it to Cloudflare Pages and point a subdomain at it. See web/README.md.

License

MIT — open source, use it however helps.