# Flux for soldering

> Flux cleans the metal, prevents oxidation and helps solder flow; it comes as paste, liquid and powder, and is removed afterwards with pickle.

- Source: https://www.711grados.com/en/flux-for-soldering/
- Language: en
- Note: This entry was drafted with the help of AI and is pending review by the author.
- Published: 2026-07-21
- Updated: 2026-07-21
- Translation (es): https://www.711grados.com/es/fundente-flux/
- Author: Sandra Sánchez
- Site: 711 Grados (https://www.711grados.com/)

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Flux is a product applied to the pieces before heating. It coats the metal, stops it from oxidizing in the flame and lets the solder run to the joint. Without flux, solder barely adheres.

## Properties

- **Function:** clean, shield from oxygen and help the solder flow.
- **Forms:** paste, liquid and powder.
- **Base:** borates and fluorides, in general.
- **Removed with:** pickle and warm water.
- **Variants:** for gold and silver, for steel and for soft solders.

## Uses in jewelry

- Soldering silver, gold, copper and brass.
- Annealing without forming firescale.
- Melting metal in the crucible.

## Pros and cons

### Advantages

- Greatly improves the joint.
- Reduces oxidation when heating.
- Inexpensive and long-lasting.

### Limitations

- It stays on and requires pickling.
- Can spatter or give off fumes.
- If overheated, it turns glassy.

## Care and cleaning

- Apply a thin coat with a brush.
- Close the jar so it does not dry out.
- Ventilate: the fumes should not be breathed.

## See also

- [Soldering for jewelry](https://www.711grados.com/en/jewelry-soldering/)
- [Pickling: cleaning oxides after soldering or annealing](https://www.711grados.com/en/pickling-metal/)
- [Jeweler's torches: gas, oxygen and mini torch](https://www.711grados.com/en/jewelers-torches/)