## Common ground
Both options refer to calcium tartrate, a chemical compound derived from tartaric acid.
## Options at a glance
**2918.13 – Salt of tartaric acid**
- **Defining trait:** Chemically classified as a salt of tartaric acid under organic chemistry nomenclature.
- **Typical examples:** Pure, refined calcium tartrate used in pharmaceuticals or food additives.
- **Best fit when:** The product is chemically defined, purified, and intended for use where its molecular structure matters (e.g., in medicine or lab reagents).
**3824.99 – Crude calcium tartrate**
- **Defining trait:** Not refined; contains impurities or is produced as a byproduct, often from industrial processes like winemaking.
- **Typical examples:** Residual calcium tartrate from wine fermentation or crude precipitates from industrial waste streams.
- **Best fit when:** The product is unrefined, low-purity, or used in bulk applications where purity is not critical (e.g., as a raw material or in agriculture).
## Key differences
| Criteria | 2918.13 – Salt of tartaric acid | 3824.99 – Crude calcium tartrate |
|------------------------|----------------------------------|-----------------------------------|
| Purity | High (refined) | Low (impure, raw) |
| Chemical definition | Precise (organic salt) | General (byproduct/industrial) |
| Typical use | Pharmaceuticals, food grade | Industrial feedstock, waste reuse |
## How to choose
- Is the product purified and chemically defined? → 2918.13
- Is it a byproduct or unrefined residue from an industrial process? → 3824.99
## Overlaps & pitfalls
A product may be both crude and a salt of tartaric acid, but the key distinction is purity and processing level. If the product is refined, use 2918.13; if crude, use 3824.99. The main function (e.g., pharmaceutical vs. industrial) should guide the choice—no priority rule is implied by HS codes