Cold Glass, Warm Flame: Oil Lamps Through the Winter

Winter is when lamps get used most and damaged most, and the two facts are related. Cold rooms, cold windowsills, condensation and thermal shock all arrive at once, and a chimney that survived three summers can crack in November for reasons that seem mysterious until you think about the temperature gradient across it.

Why glass cracks in winter

Glass expands when hot. Heat one part of a chimney quickly while another part stays cold and the difference in expansion opens a crack, usually vertically from the base. A lamp lit on a freezing windowsill is being asked to do exactly that.

Warm the room, then the lamp

Bring a lamp in from a cold porch or car and let it reach room temperature before lighting. Start with the wick very low for the first few minutes and raise it only once the chimney has warmed through. Those two habits prevent most winter breakages.

Draughts are the hidden culprit

A cold draught striking one side of a hot chimney does the same job as cold water. Sash windows, letterboxes and the gap under a door are the usual sources. Move the lamp half a metre and the problem often disappears entirely. Replacement chimneys are a stock item at sellers such as Lamplight, but it is cheaper to stop breaking them.

Condensation inside the font

A partly filled lamp stored in an unheated room breathes as the temperature swings, and moisture collects in the fuel. The result is a wick that spits, a flame that will not settle and a burner that corrodes from the inside. Store lamps either full or properly empty and dry.

Fuel behaves differently when cold

Liquid paraffin thickens slightly in the cold and draws up the wick more slowly, which is why a lamp brought in from the shed lights reluctantly and burns low for the first quarter of an hour. Give it time rather than winding the wick up, or you will have soot as soon as it warms.

The heating question

A lamp gives out a small amount of heat and no useful warmth for a room, and anyone thinking of one as backup heating during a winter outage should stop there. Never bring a garden, camping or workshop heating appliance indoors as a substitute. Layers, a closed door and a good sleeping bag are the real answer.

A winter routine that works

• Fill and trim in daylight, before the afternoon goes dark at four.
• Let cold lamps warm up indoors for half an hour before lighting.
• Keep the flame low and away from draughts, curtains and frosted windows.
• Ventilate even in cold weather, since a sealed warm room and an open flame are a poor pairing.
• Let the glass cool fully before cleaning it, and never wash a warm chimney under a cold tap.

Dark afternoons and household rhythm

The genuine winter argument for a lamp is not emergencies at all. It is the stretch between four and six in the afternoon when the house is dim, everyone is tired and the overhead light feels like an office. One lamp on the kitchen table changes that half of the day considerably.

Putting them away in spring

Drain, wipe, dry the burner and store the chimney wrapped separately rather than sitting on the lamp where a knock will chip the rim. Replace the wick at the start of each season rather than the end, so you find out about a seized wick wheel in daylight in October and not during the first storm.