TCC’s borax, also known as sodium, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and the salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.
The term borax is used for a number of closely related minerals or chemical compounds which vary in their crystal water content, but usually “borax” refers to the decahydrate. Commercially sold borax is usually partially dehydrated.
Borax is used as a food additive in some countries but is banned in the United States. As a consequence, certain foods, such as caviar produced for sale in the US contain higher levels of salt to assist in preservation. In Indonesia borax is a common, but forbidden additive to such foods as noodles, bakso (meatballs), and steamed rice. The country’s Directorate of Consumer Protection warns of the risk of liver cancer with high consumption over a period of 5 to 10 years.
Borax occurs naturally in evaporated deposits produced by the repeated evaporation of seasonal lakes. The most commercially important deposits are found in Turkey; Boron, California; and Searles Lake, California. Also, the, Atacama desert in Chile, newly-discovered deposits in Bolivia, and in Tibet and Romania. Borax can also be produced synthetically from other boron compounds. Naturally occurring borax is refined by process of re-crystallization.
Borax, sodium tetraborate decahydrate, is not acutely toxic. It’s LD50 (median lethal dose) score is tested at 2.66 g/kg in rats. A significant dose of the chemical is needed to cause severe symptoms or death. The lethal dose is not necessarily the same for humans.
Sufficient exposure to Borax dust can cause respiratory and skin irritation. Ingestion may cause gastrointestinal distress including nausea, persistent vomiting, abdominal pain, and diarrhea. Effects on the vascular system and brain include headaches and lethargy, but are less frequent.
The term borax is often used for a number of closely related minerals or chemical compounds that differ in their crystal water content:
- Anhydrous borax (Na2B4O7)
- Borax pentahydrate (Na2B4O7·5H2O)
- Borax decahydrate (Na2B4O7·10H2O)
Borax is generally described as Na2B4O7·10H2O. However, it is better formulated as Na2[B4O5(OH)4]·8H2O, since borax contains the [B4O5(OH)4]2− ion. In this structure, there are two four-coordinate boron atoms (two BO4 tetrahedra) and two three-coordinate boron atoms (two BO3 triangles).
Borax is also easily converted to boric acid and other borates, which have many applications. The “decahytrate” is sufficiently stable to find use as a primary standard for acid base titrimetry.
Borax has a wide variety of uses. It is most commonly known for its use in laundry and cleaning products such as “20 Mule Team Borax” and “Boraxo” powder and soap. Sodium borate is also used in biochemical and chemical laboratories to make buffers, e.g. for jell electrophoresis of DNA, such as TBE or the newer SB buffer or BBS (borate buffered saline) in coating procedures. Borate buffers are also used as preferential equilibration solution in DMP-based cross-linking reactions.
Borax is a source of borate that has been used to take advantage of the co-complexing ability of borate with other agents in water to form complex ions with various substances. Borates as a suitable polymer bed are used in medicine to diagnose hyperglycemia in diabetes mellitus. Borate and a proprietary synthetic amino acid, Deselex (from Henkel) have been used to complex water “hardness” cations to make a non-precipitating water “software”.
A mixture of borax ammonium chloride is used as a flux when welding iron and steel. Borax is replacing mercury as the preferred method for extracting gold in small-scale mining facilities. The method is called the borax method and is used in the Philippines.
Borax is also used to make putty. A rubbery polymer sometimes called flubber, gluep or glurch can be made by cross-linking polyvinyl acetate with a borax. Making flubber from polyvinyl acetate-based glues, such as Elmer’s Glue, and borax is a common elementary education experiment.
Other uses for Borax:
- Ingredient in enamel glazes
- Component of glass, pottery, and ceramics
- Borax can be used as an additive in ceramic slips and glazes to improve fit on wet, greenware, and bisque
- Fire retardant
- Anti-fungal compound for fiberglass and cellulose insulation
- Moth proofing 10% solution for wool
- Anti-fungal foot soak
- Precursor for sodium perborate monohydrate that is used in detergents, as well as for boric acid and other borings
- Tackifier ingredient in casein, starch and dextrin-based adhesives
- Precursor for Boric acid, a tackifier ingredient in polyvinyl acetate, polyvinyl alcohol-based adhesive
- Fluoride detoxification
- Treatment for thrush in horses’ hooves
- Used to make indelible ink for dip pens by dissolving shellac into heated borax
- Curing agent for snake skins
- Curing agent for salmon eggs, for use in sport fishing for salmon
- Swimming pool buffering agent to control the pH
- Neutron absorber used in nuclear reactors and spent fuel pools to control reactivity and to shut down a nuclear chain reaction
- As a micronutrient fertilizer to correct boron-deficient soils
- To clean the brain cavity of the skull for mounting
- To color fires with a green tint
- Was traditionally used to coat dry-cured meats such as hams to protect them from becoming fly-blown during further storage
- Is found in some commercial vitamin supplements
- For stopping car radiator and engine block leaks
- As an important component in Slime
- Is used by the modern blacksmith in the process of fort welding