Container & Vessel Standards

Glass Container Requirements

Per ASTM F2417, glass containers must be evaluated for thermal resistance. They must:

• Not crack, shatter, or break during a full burn cycle.
• Withstand rapid temperature changes (thermal shock).
• Have wall thickness sufficient for the jar size and wick.

Preferred options: tempered glass, thick-walled apothecary jars, and purpose-made candle vessels. Avoid repurposed food jars, thin craft glass, or any container with visible seams at the base.

Metal Container Requirements

• Smooth, non-sharp edges at the rim to prevent cuts.
• Exterior surface must not reach temperatures that cause burns on incidental contact.
• Paint or coating must be food-grade or heat-safe.
• Sufficient gauge (wall thickness) — thin tins can warp at high temperatures.

Test maximum external temperature with a digital thermometer during a full burn cycle.

Jar Temperature Guidelines

The external surface temperature of a candle container must remain at a level that does not present a burn risk when handled:

• Exterior surface: below 140°F (60°C) during the burn.
• Side walls: ideally below 120°F (49°C) for comfortable handling.
• If surface temperatures exceed these thresholds, consider thicker glass, a smaller wick, or a different container.
• Include handling warnings on the label for containers that get hot during use.