A polished metal surface behind the flame sends the light that would travel backward toward your work instead, which can roughly double the useful light in that direction. A tin-can lid polished with fine ash or sand, a curved sheet of metal or smoothed aluminium foil all work. Keep the reflector clear of the flame and away from anything that burns.
Part of Oil Lamp Construction
A polished metal surface behind a flame turns back light that would otherwise be wasted, at the cost of no fuel, only metal and polishing.
A Reflector Redirects, It Does Not Create
A flame radiates in every direction. Light going behind the lamp lights nothing useful. A reflector behind the flame turns that light around. If it catches about half the flame’s output and reflects most of it forward, the forward light is at most about twice what it was; that is consistent with the overview’s statement that a reflector can effectively double the useful brightness in the direction you are working. It will not do better than that, and it adds nothing to the light going the other way.
The overview lists three options:
- Tin-can lid, polished with fine ash or sand.
- Curved reflector — bend sheet metal into a parabolic curve behind the flame.
- Aluminium foil — crumpled then smoothed gives a good diffuse reflector.
A flame is not a point, so a curve concentrates light only roughly; do not expect a sharp beam.
Method
Step 1: Make or choose the surface. Polish a lid with fine ash or sand until it shines; or crumple foil and flatten it.
Step 2: Position. Put it behind and slightly to the side of the flame, angled toward the work. Leave a clear gap so air reaches the flame.
Step 3: Fix. Mount it so it cannot fall onto the lamp or lean on the glass.
Step 4: Check. Compare the page light with and without it.
Common Mistakes
- Placing it where it can touch the flame or wick. It can quench the flame and soot.
- Leaving soot on it. A sooty surface reflects poorly. Wipe it clean when cool.
- Using plastic-backed or mirror-glass reflectors. Plastic melts and glass can crack from heat.
Safety
A reflector also reflects heat
A metal reflector near the flame gets hot and throws heat toward whatever it faces. Keep combustible material, curtains and walls clear, and do not touch it while the lamp is lit. A sooting flame that blackens the reflector is burning incompletely, which makes carbon monoxide, and you cannot smell it: ventilate with an inlet and an outlet.
What’s Next
- Learn next: Glass Chimneys — the next fitting for a cleaner flame
- Combine with: Betty Lamp & Cruise Lamp — a hung lamp with a reflector behind it