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DIY silver solder flux

Updated July 20, 2017

There are many ways to make jewellery, from stringing and weaving beads to crafting pieces from precious metals, clay and wood. But making silver jewellery items like rings and earrings often requires soldering metal pieces together. If you don't want to use one of the commercially available fluxes on the market, you can make a batch of flux paste at home to use for soldering silver, copper and other metals.

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  1. Buy borax, trisodium phosphate (TSP) and boric acid at a DIY or hardware shop. Each product has a common household use, so they should be easy to find. Borax is used for whitening clothes, TSP is used as a cleaner and boric acid is used to repel nasty insects.

  2. Mix together 60 ml (2 fl oz) Borax, 60 ml (2 fl oz) TSP and 90 ml (3 fl oz) of boric acid in a pan. To make a larger quantity, double the ingredients -- but always maintain the 2:2:3 ratio.

  3. Add approximately 250 ml (1 cup) of water to the ingredients in the pan. You don't need to be precise. The water is used to help dissolve the chemicals, so your flux mixture will just be more or less concentrated depending on how much water you use.

  4. Place the pan on the hob and warm the ingredients to boiling point. Reduce the heat and let it simmer until the ingredients have dissolved completely.

  5. Place the flux in a plastic bottle or glass jar with a tight-fitting lid when cooled.

  6. Tip

    Depending on how you like to work, you can decant flux into a spray bottle to squirt on to your piece, or you can simply use a paintbrush to apply the flux to the desired area.


    Keep flux mixture out of reach from children or animals.

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Things You'll Need

  • Borax
  • Boric acid
  • Trisodium phosphate (TSP)
  • Pan

About the Author

Janet Lee-Amies
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