The kit · alkali
Borax: what it removes and where never to use it
Sodium tetraborate: a mild alkali and laundry booster. Products sold as "borax substitute" can contain sodium sesquicarbonate, a different chemical; do not assume equivalent dosing or compatibility.
- pH
- 9.2
- Safe on
- 0 materials
- Never on
- 2 materials
- UK name
- check local availability and the exact product label
01 How to use it
Use only a product labelled for the task at its stated dose and water volume. Do not substitute a chemically different borax substitute using the same recipe.
- Toxic if swallowed; keep away from children and pets.
How it works
Alkalis break down fats and acidic soils and help detergents work. Strong alkalis damage protein fibres such as wool and silk, and can dull stone and wood finishes.
On a label
On an ingredient list, borax shows up as sodium tetraborate, sodium borate or disodium tetraborate.
Borax is ruled out on leather and suede. Avoid routine home use on baby clothes, a wool sweater, silk, a wool rug and a wood table. The table gives general restrictions; an unlisted restriction is not proof that a product is compatible.
02 What it works on
- Tannin
- Protein
- Living mould
- Oil and fat
Borax is strongest against tannin and protein.
03 Where it is safe
| Material | Verdict | Why |
|---|---|---|
| Leather | Never | It dries and discolours leather. |
| Suede and nubuck | Never | It discolours suede. |
| Baby clothes | Avoid | Skip it for baby clothes; rinse residue is a needless risk for small children. |
| Wool and cashmere | Avoid | Alkaline soaks harm wool and silk. |
| Silk | Avoid | Alkaline soaks harm wool and silk. |
| Wool rug | Avoid | Alkaline soaks harm wool and silk. |
| Wood furniture and floors | Avoid | It can dull or haze a finish. |
| Clothes | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| White shirt | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Jeans | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Linen | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Sheets and bedding | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Towels | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Polyester | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Leggings and activewear | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Rayon and viscose | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Carpet | Test first | Rinse it out fully; powder residue stiffens pile and attracts dirt. |
| Fabric couch | Test first | Rinse it out fully; powder residue stiffens pile and attracts dirt. |
| Microfiber couch | Test first | Rinse it out fully; powder residue stiffens pile and attracts dirt. |
| Velvet upholstery | Test first | Rinse it out fully; powder residue stiffens pile and attracts dirt. |
| Car seats | Test first | Rinse it out fully; powder residue stiffens pile and attracts dirt. |
| Mattress | Test first | Rinse it out fully; powder residue stiffens pile and attracts dirt. |
| White sneakers | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Marble | Test first | Not acidic, but rinse it off; residue dulls polish. |
| Granite | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Quartz countertop | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Tile grout | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Painted walls | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
| Plastic containers | Test first | No material-specific permission is established by this general entry. Check the exact item and product labels and pretest; if compatibility is unknown, consult the manufacturer or a professional. |
04 Mixing
The combinations people ask about most, and what actually happens.
- Can you mix chlorine bleach and borax? Caution a product-dependent combination
- Can you mix white vinegar and borax? Pointless a neutralised, weaker solution
- Can you mix oxygen bleach and borax? Caution a product-dependent combination
05 Questions
What stains does borax remove?
It works best on tannin, protein, living mould and oil and fat.
How do you use borax safely?
Use only a product labelled for the task at its stated dose and water volume. Do not substitute a chemically different borax substitute using the same recipe. Toxic if swallowed; keep away from children and pets.
What should you never mix with borax?
This reference cannot establish that any commercial cleaner has no dangerous mixing partner. Do not combine cleaners unless their exact manufacturers explicitly permit the use; rinsing alone does not establish compatibility for later treatment.
Where should you never use borax?
On leather and suede. It dries and discolours leather.