Search for borax powder in the UK and you will see the same chemical described as technical grade, laboratory grade, reagent grade, pharmacopoeia grade, “pure” or “premium”. Some of these labels describe a real, documented standard. Others are marketing words. This guide explains what each grade actually means, what paperwork a genuine supplier should give you, and how to choose the right borax for flux, glaze, laboratory and other professional work without paying for purity you do not need.
Grade, form and product: three different questions
Before comparing grades, it helps to separate three things that are often mixed up on product pages:
- Form is how much water is locked into the crystal: decahydrate, pentahydrate or anhydrous. It changes how much boron you get per gram. Our guide to borax decahydrate, pentahydrate and anhydrous covers this in detail.
- Grade is the quality standard the material is made and tested to: how pure it is, which impurities are limited and how that is documented.
- Product is what is actually in the bag. “Borax substitute” is a different product altogether: it contains no boron and is designed for household laundry and cleaning.
A useful listing tells you all three. If a page says only “borax” with no CAS number, form or grade, ask before you buy.
The main grades of borax explained
Technical grade borax
Technical (or industrial) grade is the workhorse grade for trade and manufacturing. It is sodium tetraborate of high purity, produced for processes where the borate content matters but trace impurities at very low levels do not. Typical professional uses include soldering and brazing flux, ceramic glazes and enamels, glass, timber and restoration work under the relevant regulations, industrial cleaning and water conditioning. A good technical grade product still states its purity, CAS number and batch number, and comes with a Safety Data Sheet.
Laboratory and reagent grades
Reagent grades are made to a published specification, such as those set by the American Chemical Society (ACS) or the European Pharmacopoeia (Ph. Eur.), with stated limits for assay and for named impurities such as chloride, sulfate and heavy metals. Each batch is tested against that specification and the results are reported on a Certificate of Analysis. You need a reagent grade when a standard method names one, for example in accredited testing, pH reference work or analytical titrations. For general bench work, many laboratories find that a high-purity technical grade with a Certificate of Analysis is sufficient. The deciding factor is what your method or quality system specifies, not the price.
Pharmacopoeia grades
Some suppliers sell borax made to a pharmacopoeia monograph (Ph. Eur., BP or USP) for regulated manufacturers whose own processes and quality systems require it. These grades come with extensive documentation and are bought through specialist channels. They are not a “safer” or “edible” borax: the hazard classification is exactly the same for every grade.
What about “food grade” or “cosmetic grade”?
Treat these labels with suspicion. Borax is classified as toxic to reproduction, and it must not be used in food, drinks, supplements, cosmetics or toys. We do not sell borax for any of those uses, and no grade of borax should be used for them.
Borax grades compared
| Grade | Made and tested to | Typical documents | Typical users |
|---|---|---|---|
| Technical / industrial | Supplier’s own specification | SDS, batch number, Certificate of Analysis on request | Jewellers, smiths, potters, restorers, manufacturers |
| Laboratory / reagent | Published reagent specification (e.g. ACS, Ph. Eur.) | SDS, batch Certificate of Analysis against the specification | Testing and research laboratories |
| Pharmacopoeia | Pharmacopoeia monograph | SDS, Certificate of Analysis, further quality documents | Regulated manufacturers only |
All three grades carry the same GB CLP classification: Repr. 1B, H360FD.
How to read a borax product listing
Whichever grade you need, a genuine professional listing should let you tick off the following:
- Chemical name and CAS number. Ordinary borax powder is sodium tetraborate decahydrate, CAS 1303-96-4. Pentahydrate and anhydrous borax have different CAS numbers.
- Purity stated as a figure. “Pure” or “premium” on its own means little. Look for a percentage and, ideally, a Certificate of Analysis you can request.
- Hazard labelling. Genuine borax carries the GHS08 health hazard pictogram, the signal word “Danger” and H360FD. If a product called “borax” has no hazard label at all, it is probably a substitute.
- A Safety Data Sheet. Suppliers of hazardous substances must provide an SDS to professional users. Sections 7, 8 and 13 cover storage, exposure controls and disposal.
- Professional use only. Because of its classification, genuine borax may not be supplied to the general public in Great Britain. A supplier selling it as a home or children’s product is a warning sign. Our article Is borax banned in the UK? explains the rules.
- Batch traceability. A batch or lot number on the pack lets you match it to its certificate and record it in your COSHH and quality records.
Choosing the right grade for the job
Flux for soldering, brazing and forge welding
Technical grade decahydrate is the usual choice. What matters most is that the powder is clean, dry and free-flowing. See our borax flux guide for mixing pastes and solutions.
Ceramic glazes, enamels and glass
Technical grade is standard for studio and small-batch work. Record the batch and use the correct material entry in your glaze software, because the oxide analysis depends on the form. More in our guide to borax for pottery and ceramic glazes.
Laboratory buffers and solutions
Use the grade your method names. Where no grade is specified, a high-purity technical grade with a batch Certificate of Analysis is often acceptable for routine preparation. Our article on how to dissolve borax powder covers solubility and making up solutions.
Household laundry and cleaning
No grade of genuine borax is the right choice here. For home use, choose a borax substitute, which contains no boron.
Pack size, storage and shelf life
Borax does not go off chemically, but borax decahydrate cakes when it picks up moisture and can turn chalky in warm, dry storage. Buy a pack size you can use while it is still free-flowing, keep it sealed in its original labelled container in a cool, dry place, and write the opening date on the pack. For regular trade use, a larger pack usually works out cheaper per kilo. For occasional bench work, a smaller pack stays in better condition. Bulk buyers can see our industrial borax page.
Safety box: every grade of borax
Borax (disodium tetraborate) is classified under GB and EU CLP as Repr. 1B, H360FD: may damage fertility, may damage the unborn child. A higher grade does not mean a lower hazard. Borax is supplied for professional, industrial and laboratory use only.
- Keep out of reach of children and away from pets, food, drink and animal feed.
- Wear nitrile gloves and safety glasses when weighing, mixing or heating borax, and avoid raising dust.
- Do not swallow. Do not eat, drink or smoke where borax is handled, and wash hands afterwards.
- Avoid if pregnant, if you may be pregnant or are trying to conceive.
- Not for use on skin, in food, in cosmetics or in toys such as slime.
- Always follow the product label and Safety Data Sheet, and carry out a COSHH assessment for workplace use. See our borax safety guide.
Frequently asked questions
What does technical grade borax mean?
Technical grade borax is high-purity sodium tetraborate made for trade and industrial processes such as flux, glazes and cleaning. It is tested to the supplier’s own specification rather than a published reagent standard, and should come with a Safety Data Sheet and a stated purity.
Is laboratory grade borax better than technical grade?
It is tested to a tighter published specification, with limits for named impurities, which matters when a standard method requires it. For flux, glaze and general workshop use, technical grade is the normal choice. The hazard classification is the same for both.
How can I tell genuine borax from borax substitute?
Genuine borax lists sodium tetraborate and CAS 1303-96-4 (for the decahydrate) and carries the health hazard pictogram with H360FD. Borax substitute contains no boron, is usually a blend of sodium carbonate and sodium bicarbonate (sodium sesquicarbonate), and is sold for household cleaning.
Can I buy borax powder in the UK as a private individual?
Genuine borax may not be supplied to the general public in Great Britain because of its reproductive toxicity classification. It remains available for professional, industrial and laboratory use. Household users should choose a borax substitute.
Does borax powder expire?
Borax is chemically stable and does not go off, but the decahydrate can cake or turn chalky depending on storage. Keep it sealed, dry and cool, and use older stock first.
Sources
- ECHA, substance information for disodium tetraborate: harmonised classification Repr. 1B, H360FD. echa.europa.eu
- HSE, UK REACH: safety data sheets and restrictions on supplying substances to the general public. hse.gov.uk/reach
- HSE, COSHH guidance for businesses. hse.gov.uk/coshh
Looking for technical grade borax? Our 99.9% pure borax powder is sodium tetraborate decahydrate (CAS 1303-96-4) in 900g and 3kg packs, supplied with a Safety Data Sheet for trade, workshop and laboratory users. Certificates of Analysis are available on request through our contact page. Orders ship from the EU in 3–7 working days. Browse the full borax powder range.