Candle Jars

Jar internal diameter is the primary variable - it determines how many wicks you need and which wick series to start with. A 30cl jar at approximately 7cm internal diameter is the most practical single-wick starting point for most container wax blends and covers the widest range of tested recipes. Smaller jars like the 9cl Lotti suit gift candles and samplers. Vessels above approximately 9-10cm diameter typically need double-wicking to achieve a full melt pool.

There is no container-specific legislation for candles in the UK or EU - GPSR applies to the finished candle as a product. In practice, most standard drinkware is annealed and thermal shock tested, making it well suited to candle use. The key consideration is prior usage in candle applications rather than a specific glass type. Counterintuitively, thick glass can be more prone to stress fractures than thin glass, because a large temperature differential between the hot glass and a cold surface - particularly during the final burn - creates more thermal stress, not less. Always burn candles on a heat-resistant surface.

The 30cl Lotti jar holds approximately 220g of finished mixture - wax and fragrance oil combined - at a standard fill level. When testing a new vessel, run a few test pours to confirm your exact fill weight before scaling up to a production batch.

Lids are not a safety requirement. Their main practical value is keeping the candle clean between burns and during storage - dust and debris on the wax surface affects both appearance and, over time, burn performance. They also trap the fragrance, so removing the lid gives a pleasing initial scent release before the candle is even lit. For retail products, a lid also protects the wax surface and wick during transit and handling.

Coloured and frosted glass does not meaningfully affect burn performance - the heat dynamics are driven by glass thickness and geometry, not surface finish or colour. The practical difference is that darker or opaque glass makes it harder to observe the melt pool during test burns, which requires extra care when wicking. Coloured glass also hides cosmetic imperfections in the wax surface such as frosting, which some makers consider an advantage for soy candles.

Glass jars and metal tins both work as candle containers but behave differently. Glass transfers heat more slowly and lets the customer see the candle burn; metal conducts heat faster, which affects melt pool behaviour near the base. Glass jars are the dominant format for premium retail candles; tins are common for travel and gift-range products. Wick selection should always be tested specifically for the vessel regardless of material.