How to Apply Flux Rosin for Soldering

Written by ashton daigle
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How to Apply Flux Rosin for Soldering
Rosin flux prevents oxidation of metals and strengthens soldering bonds. (Arthur S. Aubry/Stockbyte/Getty Images)

Soldering is a technique for bonding two types of metal together, and flux is a material that assists in the process. Metals tend to oxidise, and flux eliminates the oxidation, thus making the soldering bond, or joint, stronger. A type of flux commonly used in electronics is derived from rosin, a substance extracted from pine sap.

Skill level:
Moderately Easy

Things you need

  • Rag
  • Small paintbrush (possible)

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  1. 1

    Plug in your soldering iron or gun and allow it to heat up.

  2. 2

    Clean the surfaces of the metals you are going to join by wiping them gently with a soft rag.

  3. 3

    Open the container of rosin flux and stir it with the brush attached to the underside of the lid. Most rosin fluxes come in containers that have a built-in brush. If your container does not, use a small paintbrush like those used for painting models. Stir the rosin flux well until it is light grey in colour.

  4. 4

    Brush a thin, even layer of rosin flux onto the surfaces you are soldering. Use small, light strokes to apply the flux. Only a small amount is needed.

  5. 5

    Hold the roll of solder just above the area you are joining and apply the tip of the soldering iron to it. Melt the solder to the area you are binding. Allow a few seconds for the solder to dry.

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