A well-run oil lamp should be close to odourless. If the room smells of anything other than dinner while the lamp is burning, something is wrong, and the cause is almost always in the bottle or in the wick height rather than in the lamp itself.
The smell of unrefined fuel
Lamp oil is graded by how thoroughly it has been refined. The cheaper products contain more of the aromatic compounds that a proper refining process removes, and those are what you smell: a faint industrial or waxy odour that builds over an evening and settles into curtains. There is no technique that fixes it, because the smell is the fuel.
Do not buy the cheap scented oil
The worst combination on the shelf is a cheap base oil with a strong fragrance added to hide it. It burns dirtier, blackens the chimney faster and produces a sweet chemical smell that most people find unpleasant after twenty minutes. If you want fragrance, use a diffuser and burn plain fuel; buying ultra-pure liquid paraffin from a specialist such as https://lamplight.us.org/ costs a little more per litre and removes the problem entirely.
Smell that means something is wrong
A sharp solvent smell means the wrong fuel is in the fount and the lamp should be extinguished immediately. A strong smell at the moment of extinguishing is normal and brief, and the way to minimise it is to turn the wick right down before putting the flame out rather than blowing hard across a full flame.
Soot smell and the wick
If the odour is smoky rather than chemical, the flame is too high and unburnt carbon is going into the room. Lower the wick, check for draughts, and clean the chimney. A lamp that constantly smells of smoke is not producing light efficiently either, so fixing it improves both.
Reducing smell in practice
- Use the most refined fuel you can buy and keep the bottle sealed.
- Trim the wick square before every few burns.
- Set the flame low and let it stabilise before you sit down.
- Turn the wick down before extinguishing rather than blowing it out sharply.
- Keep a door or window slightly open whenever the lamp is lit.
Ventilation is not optional
An open flame uses oxygen and produces combustion products, and a small closed room concentrates both. This is not a reason to avoid lamps; it is a reason to keep a door ajar and to avoid burning several flames in a sealed bedroom for hours. If anyone in the room develops a headache or feels drowsy, put the flame out and ventilate.
People who should be more careful
Anyone with asthma or another respiratory condition will notice a poorly run lamp long before other people do, and should treat plain, well-refined fuel and a low flame as the minimum standard. If burning a lamp reliably provokes symptoms, stop and speak to a doctor rather than experimenting with different oils.
The cost calculation
Cheap fuel saves a small amount per litre and costs you chimneys, cleaning time and the pleasure of the room. A lamp is not an expensive thing to run in the first place, so the fuel is the last place to economise. Buy the plain refined oil, keep the flame low and the lamp will be effectively scentless.
