A lamp wick must be a strip or cord of absorbent plant fibre, and 100% cotton is the best choice. Its width sets the flame size, from 3 to 5 mm for a nightlight to 15 to 20 mm for a work light, and its construction (twisted, braided or flat) sets how evenly it burns. Never use nylon, polyester or blended fabric, which melt instead of wicking and give off toxic fumes.
Part of Oil Lamp Construction
A wick is a strip or cord of absorbent fibre that carries fuel to the flame. Its fibre, width and construction decide how bright, steady and smoky the lamp burns.
A Wick Works Because Fuel Climbs Through Its Fibres
Fuel rises through the tiny spaces between fibres by capillary action and burns at the exposed tip. The flame consumes fuel, not the wick, as long as the wick is wet all the way up. Three choices decide how it performs:
- Fibre. Cotton is the best; jute, hemp, milkweed floss and paper are weaker. See Cotton & Plant Fiber Wicks.
- Width. Wider wick, bigger flame, more fuel burned. See Wick Sizing & Brightness.
- Construction. Twisted, braided or flat. See Braided vs Twisted Wicks.
Test A Fibre Before You Build With It
Stand one end of a short length in the fuel you plan to burn. The fuel should visibly darken the fibre as it climbs. If it stays at the bottom, or beads on the surface, the material is not absorbent enough or is treated; try another.
Width Sets The Flame
The overview’s widths: 3 to 5 mm gives a dim nightlight, 8 to 12 mm a reading light and 15 to 20 mm a bright work light. See the sizing page for the fuel each one burns.
What Not To Use
- Synthetics (nylon, polyester) and blends melt rather than wick, and burn with toxic fumes.
- Fabric sold as flame-retardant is designed not to burn and will wick and burn poorly.
- Rolled paper works briefly, then chars and crumbles.
Common Mistakes
- Treating “mostly cotton” as cotton. A blend melts. Use 100% cotton.
- Using a wick that does not reach the fuel. The wick must dip into the reservoir; a short wick starves the flame as the fuel level falls.
- Lighting a dry wick. Let it soak in the fuel first, so the fibre does not burn instead of the fuel.
Safety
Synthetic fumes and runaway flames
Burning or melting synthetic fabric releases toxic fumes in the room where you are breathing. A wick that is too wide for its holder makes a tall sooting flame; soot is incomplete burning and incomplete burning makes carbon monoxide, which has no smell and whose first symptoms (headache, nausea, drowsiness) feel like ordinary tiredness. If a lamp smokes and you feel drowsy, put it out and move into fresh air rather than lying down.
What’s Next
- Learn next: Cotton & Plant Fiber Wicks — choosing and cutting the fibre
- Combine with: Lamp Designs — a wick needs a holder that suits its width