---
title: "Create Coating Mask"
method: POST
path: "/api/v1/parts/{part_id}/coating-masks"
tags: ["part_annotations"]
---

# Create Coating Mask

`POST /api/v1/parts/{part_id}/coating-masks`

Create a coating mask on a face (exclude from part-level coating).

Rejects with 422 if the part has no ``coating_id`` set.

## Path parameters

- `part_id` string, uuid, required

## Request body

- CoatingMaskCreate — Payload for ``POST /parts/{part_id}/coating-masks``.
  - `face_id` string, required — Topology face ID (e.g. ``face_42``).
  - `reason` 'thread_fit' | 'press_fit_bore' | 'mating_surface' | 'electrical_contact' | 'o_ring_groove' | 'other', required — Why this face should be excluded from the coating.

## Response `201`

Successful Response

- CoatingMaskRead — Response projection for a coating mask OutcomeEvent.
  - `id` string, uuid, required
  - `part_id` string, uuid, required
  - `cad_file_version_id` string, uuid, nullable, required
  - `face_id` string, required
  - `reason` string, required
  - `state` string, required
  - `created_at` string, date-time, required
  - `updated_at` string, date-time, nullable, required

## Other responses

- `422` — Validation Error

---

[API](https://skmtc.dev/prototyping/apis/prototyping-io-api.md) · [All operations](https://skmtc.dev/prototyping/apis/prototyping-io-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/prototyping/prototyping-io-api/revisions/f4a0079fbb57/schema)