Liquid paraffin is a clear, odourless mineral oil. Around the home it is used to condition and protect wooden chopping boards and utensils, lubricate light mechanisms, polish stainless steel and prevent rust. It also has medicinal uses as a laxative and skin moisturiser — a quite different product grade.
What is Liquid Paraffin?
Liquid paraffin is a highly refined mineral oil, distilled from petroleum and purified until it is clear, colourless, odourless and tasteless. It is also called white mineral oil, paraffinum liquidum or, at lighter grades, food-grade mineral oil.
It is not the same as paraffin — the fuel burned in lamps and heaters, also called kerosene or illuminating paraffin. That distinction is important and gets people into trouble. Liquid paraffin is a stable, non-volatile oil; kerosene is a volatile, flammable fuel that is toxic and must never be used on food surfaces or skin.
Grade matters, and it is the key thing to check:
| Grade | Typical use |
|---|---|
| Food-grade / USP | Chopping boards, utensils, food contact |
| Pharmaceutical | Laxatives, skin preparations, baby oil |
| Technical / industrial | Lubrication, machinery |
Only food-grade should touch anything that touches food, and only pharmaceutical grade should go on skin or be swallowed. Technical grades may contain impurities that are unsuitable for either.
What makes it useful is chemical inertness. Unlike vegetable oils, liquid paraffin does not oxidise, go rancid or polymerise into a sticky film. A wooden board oiled with olive or sunflower oil will eventually smell rancid; one oiled with food-grade liquid paraffin will not. That is the single strongest argument for using it.
It is also water-repellent, non-drying and does not conduct electricity.
What is Liquid Paraffin commonly used for?
- Conditioning wooden chopping boards, butcher’s blocks and worktops — the most common household use.
- Treating wooden utensils, spoons, bowls and knife handles.
- Lubricating light mechanisms — hinges, sliding drawers, sewing machines.
- Polishing and protecting stainless steel, reducing fingerprints and water marks.
- Preventing rust on tools and blades before storage.
- Conditioning leather, in some formulations.
Its medicinal uses are quite separate, and use pharmaceutical grade:
- As a laxative, lubricating the bowel and softening stool.
- As a skin moisturiser and emollient, in creams, ointments and baby oil.
- In eye ointments, for dry eyes.
A caution on the laxative use, since people sometimes take it casually: liquid paraffin taken by mouth interferes with absorption of the fat-soluble vitamins A, D, E and K with regular use, and carries a risk of lipoid pneumonia if it is inhaled — a genuine hazard in people who are elderly, bedbound or have swallowing difficulty. It should not be taken at bedtime lying down, and modern laxatives are generally preferred. Ask a pharmacist rather than self-treating constipation with it long term.
Common household applications
Conditioning a wooden chopping board. Clean and dry the board thoroughly, apply food-grade liquid paraffin with a cloth working along the grain, leave it to soak in for several hours or overnight, then wipe off the excess. Repeat monthly at first, then whenever the wood looks dry or pale. Oiling stops the board absorbing water, which is what causes warping and cracking. Wooden utensils and bowls need the same treatment more often, because they are washed more.
Stainless steel appliances. A few drops on a soft cloth, buffed along the grain, leaves a film that resists fingerprints and water marks.
Light lubrication. A drop on a hinge, drawer runner or sewing machine mechanism — it will not gum up as vegetable oils do. For heavier or outdoor mechanisms a proper lubricant works better.
Rust prevention. Wipe a thin film over clean, dry tools before a damp season.
How to use Liquid Paraffin appropriately
- Check the grade before use. Food-grade for anything touching food; pharmaceutical for skin.
- Apply to clean, dry surfaces, working with the grain, and let it soak in before wiping.
- Use sparingly and wipe off the excess. A surface left oily attracts dust and transfers to hands and food.
- Reapply periodically rather than heavily once.
- Store it sealed, away from heat and out of reach of children.
- Never use it on floors, stairs or any walking surface — a serious slip hazard.
Safety, surfaces and situations to avoid
Liquid paraffin is among the safer household oils — it is chemically stable, not volatile, and not readily flammable in the way kerosene is. But there are real cautions.
If swallowed, do not induce vomiting. The main hazard is aspiration — oil entering the lungs — which causes a serious chemical pneumonitis. Vomiting greatly increases that risk. Contact a doctor or poison centre with the container, particularly for a child.
Do not give it to a child as a laxative without medical advice, and never to anyone with swallowing difficulty or who is confined to bed.
Keep it away from lamp oil and fuel containers. Never decant either into an unmarked bottle — kerosene mistaken for liquid paraffin, or stored in a drinks bottle, is a recurrent and serious cause of childhood poisoning in South Africa.
Other points:
- Not for use with latex. Like all oil-based products it degrades latex — never with condoms or latex gloves.
- Avoid porous stone, fabric and carpet, where it stains.
- Wear gloves for extended work with technical grades, which can irritate skin.
- Rinse eye contact with water for several minutes and seek advice.
- Dispose of waste oil responsibly — not down drains or onto soil.
Seek medical advice if swallowed, inhaled, or if skin irritation develops and persists.
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Frequently asked questions
What is liquid paraffin used for? Around the home, conditioning wooden boards and utensils, light lubrication, polishing stainless steel and preventing rust. It also has medicinal uses as a laxative and skin moisturiser.
Is liquid paraffin the same as paraffin? No, and the difference matters. Liquid paraffin is a refined, stable mineral oil. Paraffin (kerosene) is a volatile, flammable fuel that is toxic and must never be used on food surfaces or skin.
Can I use it on a chopping board? Yes, if it is food-grade. It is preferred over vegetable oils because it does not go rancid.
Why not just use cooking oil on wood? Vegetable oils oxidise and go rancid, leaving a smell and a sticky film. Liquid paraffin is chemically stable and does not.
Is it safe to swallow? Pharmaceutical grade is used as a laxative, but not casually — regular use blocks absorption of vitamins A, D, E and K, and there is a risk of lung damage if inhaled. Ask a pharmacist.
What if a child swallows it? Do not induce vomiting, as that risks it entering the lungs. Contact a doctor or poison centre with the container.
Can I use it on leather? Some formulations are used to condition leather, but check the product first — a dedicated leather conditioner is usually better.
Does it go off? It is very stable and does not go rancid, though it should still be stored sealed and away from heat.