Candles

Material selection for candles

Stearin candles and paraffin-stearin blends rely on oleochemicals for hardness, opacity, mould release and burn behaviour. Stearic acid and palm-based stearins are used on their own in stearin candles, or blended with paraffin wax, often at around 10–30%, to make pillar and moulded candles harder, whiter and easier to release from the mould.

What the process needs. Pillar and moulded candles need a blend that contracts cleanly on cooling, resists slumping in warm conditions and burns without dripping. Container candles need good adhesion to the glass and a smooth surface after each burn. Stearic acid raises the melting point and hardness of paraffin blends, improves opacity and colour intensity, and helps release from metal moulds. Hydrogenated stearins add structure and, in some formulations, a crystalline surface. Too much stearic acid can reduce fragrance throw and change the wick size needed, so blend ratios are usually fixed by testing.

Key specification parameters. For stearic acid, check iodine value, where a lower value gives better colour and odour stability, together with titre or congealing point, colour and the C16/C18 ratio, which affects crystal structure and hardness. For palm stearin and hydrogenated palm stearin, check melting point (slip or drop point), iodine value, free fatty acid and colour. Residual unsaturation is the main cause of yellowing and off-odour in stored candles, which is why triple-pressed or fully hydrogenated grades are preferred for white and pastel candles.

Recommended product types. Triple-pressed stearic acid, including grades traded as 1838 or 1842, for high-quality pillar and stearin candles. Double-pressed grades for general blending. Palm stearin and hydrogenated palm stearin as structuring fats. Hydrogenated castor oil as a hardening additive in some specialty blends.

Documentation. Ask for lot-specific analysis and the safety data sheet. If you market candles with sustainability or vegetable-origin claims, request chain-of-custody evidence that covers the specific product and site, and ask for the certificate scope with your quotation. Candles sold to consumers in the UK and EU must also meet general product-safety rules, which in practice include fire-safety warnings, so keep the raw-material information your compliance team needs.

Handling and shipping. Stearic acid and stearins are supplied as beads, flakes or pastilles in 25 kg bags, or molten in bulk for large users. Store them cool and dry, away from heat and direct sunlight, to prevent caking and discolouration. Keep bags closed to avoid dust contamination and rotate stock. When melting in-house, avoid overheating and long holding times at high temperature, which darken stearic acid and can shorten the shelf life of the finished candles.

Burn performance. The raw material alone does not determine how a candle burns. Wick type and size, container, fragrance load and dye all interact with the wax blend. Run burn tests on every new blend and whenever you change a raw-material source, and keep retained samples of the lots used in approved production.