Borax powder (sodium tetraborate decahydrate) is a versatile boron mineral. In the UK today it is used mainly in professional and technical settings. Here is how each trade uses it.
1. Flux for Soldering and Brazing
Heated borax melts into a glassy layer that dissolves oxides and keeps metal clean, letting solder flow. Jewellers use it on silver, gold and copper; blacksmiths use it for forge welding. See our borax flux guide.
2. Ceramic Glazes and Enamels
Borax is a powerful low-fire flux. Potters add it to glazes (often as a frit) to lower melting temperature, improve gloss and reduce crazing. It is also used in vitreous enamel and borosilicate glass. For how boron works in a glaze, why raw borax is soluble and when to use a frit instead, read our guide to borax in ceramic glazes.
3. Timber Treatment and Restoration
Borate solutions soak into timber and protect it against fungal decay and wood-boring insects. Conservators use borax on historic beams and joinery.
4. Laboratory Buffer
Borax is a primary standard for titrations and a common reagent for borate buffers at around pH 9.2, used in biochemistry and electrophoresis.
5. Taxidermy and Preservation
Borax helps dry hides and botanical specimens and discourages insect damage.
6. Technical Cleaning and Water Conditioning
As a mild alkali it degreases tools and surfaces in workshops and conditions water in closed heating and cooling systems.
What About Household Uses?
Laundry boosting, stain removal and general cleaning were once popular household uses, but pure borax is no longer sold for this in the UK. Use borax substitute for these jobs instead.