The kit · acid
Lemon juice: what it removes and where never to use it
Fresh or bottled lemon juice: citric acid plus sugar and colour. Pure citric acid powder does the same job without the sugar.
- pH
- 2–2.6
- Safe on
- 0 materials
- Never on
- 1 materials
- Used in
- 7 files
01 How to use it
Dab on, sprinkle with salt for rust, and let it dry in the sun on white cotton. Rinse well afterwards.
- With sunlight it bleaches; keep it off coloured fabric.
- Never mix with chlorine bleach or unapproved cleaning products.
How it works
Acids dissolve minerals (limescale, rust, aluminium salts) and neutralise alkaline residues. They also dissolve calcium carbonate, which is why they etch marble and erode grout.
On a label
On an ingredient list, lemon juice shows up as citric acid.
Lemon juice is ruled out on marble. Avoid routine home use on clothes, jeans, linen, polyester, leggings, silk, rayon, a couch, velvet, leather, granite, a quartz countertop, a wood table and grout. The table gives general restrictions; an unlisted restriction is not proof that a product is compatible.
02 What it works on
- Minerals and metal
- Dye
- Living mould
Lemon juice is strongest against minerals and metal. It is part of the method in 7 stain files, for stains such as sunscreen and rust.
03 Where it is safe
| Material | Verdict | Why |
|---|---|---|
| Marble | Never | Citric acid etches marble, limestone and travertine within minutes. |
| Clothes | Avoid | Lemon plus daylight bleaches dyed fabric unevenly. |
| Jeans | Avoid | Lemon plus daylight bleaches dyed fabric unevenly. |
| Linen | Avoid | Lemon plus daylight bleaches dyed fabric unevenly. |
| Polyester | Avoid | Lemon plus daylight bleaches dyed fabric unevenly. |
| Leggings and activewear | Avoid | Lemon plus daylight bleaches dyed fabric unevenly. |
| Silk | Avoid | Silk can water-spot and lose dye where acid sits. |
| Rayon and viscose | Avoid | Lemon plus daylight bleaches dyed fabric unevenly. |
| Fabric couch | Avoid | Lemon plus daylight bleaches dyed fabric unevenly. |
| Velvet upholstery | Avoid | Lemon plus daylight bleaches dyed fabric unevenly. |
| Leather | Avoid | Acid and sun bleach and dry leather. |
| Granite | Avoid | Acid wears down granite sealer. |
| Quartz countertop | Avoid | Acidic cleaners can dull quartz over time. |
| Wood furniture and floors | Avoid | It can bleach wood and dull the finish. |
| Tile grout | Avoid | Acid eats into cement grout. |
| 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. |
| 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. |
| Baby 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. |
| Wool and cashmere | Test first | Wool tolerates mild acid, but the sun-bleaching effect can lighten dyes; rinse well. |
| Carpet | 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. |
| Wool rug | Test first | Wool tolerates mild acid, but the sun-bleaching effect can lighten dyes; rinse well. |
| Microfiber couch | 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. |
| Car seats | 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. |
| Mattress | 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. |
| Suede and nubuck | 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 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. |
| Painted walls | Test first | Its sugar leaves a sticky film; vinegar is the better acid for walls. |
| 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 How the files use it
Lemon juice appears in 7 stain files. The steps it is used in most:
- Lemon, salt and sun (7 files): The orange is an iron compound, so it comes out with an iron remover, not a detergent. Citric acid pulls iron into solution, and sunlight speeds it up.
05 Mixing
The combinations people ask about most, and what actually happens.
- Can you mix chlorine bleach and lemon juice? Toxic chlorine gas
- Can you mix white vinegar and lemon juice? Caution a product-dependent combination
- Can you mix baking soda and lemon juice? Pointless fizz, then salty water
- Can you mix hydrogen peroxide and lemon juice? Caution a product-dependent combination
06 Files that use it
07 Myth files
- Does Coca-Cola remove rust? Its phosphoric acid dissolves a little rust on metal, slowly. On fabric or stone it leaves a sugary brown stain.
08 Questions
What stains does lemon juice remove?
It works best on minerals and metal, which is why it appears in the files for sunscreen and rust.
How do you use lemon juice safely?
Dab on, sprinkle with salt for rust, and let it dry in the sun on white cotton. Rinse well afterwards. With sunlight it bleaches; keep it off coloured fabric.
What should you never mix with lemon juice?
chlorine bleach. Acids pull chlorine out of hypochlorite as chlorine gas, the same gas used as a weapon in the First World War. Do not combine commercial cleaners unless their exact manufacturers explicitly permit the use.
Where should you never use lemon juice?
On marble. Citric acid etches marble, limestone and travertine within minutes.