Almost any liquid or melted fat or vegetable oil works as lamp fuel, and rendered animal fat is the most available one after a collapse. Never put gasoline or other salvaged solvents in a lamp, because they give off ignitable vapour at ordinary room temperature and can flash into a fire. Kerosene burns brightest but is only safe in a lamp that keeps its fuel cool and its vapour away from the flame.
Part of Oil Lamp Construction
A wick lamp draws liquid fuel upward and burns it at the tip, so what matters is whether the fuel’s vapour stays harmless at room temperature. Rendered fat and plant oils do; gasoline and solvents do not.
A Fuel Is Safe For A Lamp Only If Its Vapour Cannot Ignite At Room Temperature
The test that matters is the flash point: the lowest temperature at which a liquid gives off enough vapour above its surface to ignite when a flame or spark reaches it. A wick lamp puts a flame a few centimetres from a reservoir of fuel. If the fuel’s flash point is below the temperature of the room, the air above the reservoir is already a flammable mixture before you light anything.
| Fuel | Typical flash point | Verdict |
|---|---|---|
| Gasoline | about -43 °C | Never. Flammable vapour at any temperature a person lives in |
| Ethanol (alcohol) | about 13 °C | Not in these lamps. Needs a purpose-built spirit lamp |
| Lamp kerosene | 38 °C or higher (specification minimum) | Usable, with care. A warm reservoir can approach its flash point |
| Diesel | 52 °C or higher (specification minimum) | Works, smokes more. Higher flash point than kerosene |
| Vegetable oils and rendered fats | well above 200 °C | Safe to store and burn in an improvised lamp |
Reading the table: a 20 °C room is 7 °C above ethanol’s flash point (20 − 13 = 7) and 63 °C above gasoline’s (20 − (−43) = 63), so the vapour over either is already ignitable before you strike a light. The same room is 18 °C below kerosene’s minimum of 38 °C (38 − 20 = 18); that margin is what heat from the lamp itself can eat into.
The flash points above are typical published specification values for these fuels, not figures from this site’s other pages. Labels and safety data sheets on salvaged containers give the real number for the product in front of you.
Match The Fuel To What You Have
- Rendered animal fat — the default when you slaughter or hunt. See Animal Fat (Tallow & Lard) and Rendering Fat for Lamp Fuel.
- Vegetable oil — cooking oil from stores or a press, even rancid or used oil. See Vegetable Oil.
- Kerosene and diesel — pre-collapse supplies only. See Kerosene & Petroleum.
What Each Fuel Costs In Burn Rate
These are the figures the oil-lamp overview gives for a moderate wick:
| Fuel | Burn rate | Hours per litre |
|---|---|---|
| Olive or vegetable oil | about 30 ml/h | about 33 |
| Rendered tallow | about 25 ml/h | about 40 |
| Lard | about 28 ml/h | about 36 |
| Kerosene | about 20 ml/h | about 50 |
Check: 1,000 ml ÷ 30 ml/h = 33 h; ÷ 25 = 40 h; ÷ 28 = 36 h; ÷ 20 = 50 h.
Common Mistakes
- Trying an unknown liquid by dropping a flame on it. If it is gasoline or a solvent, the result is a flash fire at your face. If you cannot identify a liquid from its container and label, do not burn it; use fat or oil.
- Storing lamp fuel in a drink bottle. Someone will drink it. Keep fuel in a labelled container.
- Refilling a lit or warm lamp. Fill only when the flame is out and the lamp has cooled, away from any other flame.
Safety
Gasoline in a lamp
Gasoline vapour ignites below freezing, so a gasoline lamp does not burn steadily at a wick: the vapour space in the reservoir can ignite and throw burning fuel. The same applies to camping-stove fuel, lighter fluid, paint thinner and other solvents. Treat any salvaged liquid you cannot positively identify as gasoline.
What’s Next
- Learn next: Animal Fat (Tallow & Lard) — the most available fuel
- Combine with: Wick Materials & Construction — fuel and wick have to suit each other
- Related: Fuel Siphoning & Storage — recovering and storing salvaged petroleum fuels