Since pure borax disappeared from UK supermarket shelves, borax substitute has taken its place. But they are not the same chemical, and they are not interchangeable for every job. Here is how they compare.
What is borax?
Borax is sodium tetraborate decahydrate (Na2B4O7·10H2O), a naturally occurring boron mineral. In water it forms a mildly alkaline solution (about pH 9.2) and acts as a buffer, water softener and flux. It is classified Repr. 1B, so in the UK it is supplied for professional and industrial use only. See Is borax banned in the UK?
What is borax substitute?
Borax substitute is usually sodium sesquicarbonate, or a blend of sodium carbonate (washing soda) and sodium bicarbonate (baking soda). It sits between the two in strength: stronger than bicarbonate, gentler than soda crystals, and close to borax in pH. It contains no boron.
Side-by-side comparison
| Borax | Borax substitute | |
|---|---|---|
| Chemical | Sodium tetraborate | Sodium carbonate / bicarbonate |
| pH in water | ~9.2 | ~9.5–10 |
| UK availability | Professional / industrial supply | Sold to everyone |
| Laundry booster | Yes (no longer marketed for home use) | Yes |
| Soldering / brazing flux | Yes | No |
| Ceramic glazes | Yes | No |
| Laboratory buffer | Yes | No |
| Hazard | Repr. 1B, H360FD | Eye irritant |
When to use borax substitute
For everyday household jobs, substitute is the right choice:
- Boosting laundry detergent, especially in hard water areas
- Pre-soaking stained or greying whites
- Cleaning sinks, tiles, ovens and grout
- Freshening bins and drains
A typical dose is 1–2 tablespoons per wash added to the drum with your usual detergent. Our borax substitute double pack (1800g, about 60 washes) is made for exactly this. For doses, pre-soaking and storage, see our step-by-step guide on how to use borax substitute in laundry.
When only real borax will do
Borax substitute cannot replace borax where the boron chemistry matters: as a flux for soldering and brazing, in ceramic glazes and glass, in borate buffers, and in timber preservation. For these professional applications you need genuine sodium tetraborate. Read more in our guide to borax uses.
Which should you buy?
Cleaning at home: borax substitute. Working in a workshop, studio, lab or on a restoration project: technical grade borax with an SDS.
Need borax for professional use? Our 99.9% pure borax powder is available in 900g and 3kg packs with SDS and free delivery to the UK. For home laundry and cleaning, choose our borax substitute.