Gypsum vs Concrete — What Is the Difference and Which Is Better for Candle Jars India?

Karessa Candles' jars are described as 'concrete gypsum jars.' Buyers — and even experienced candle makers — frequently ask: what exactly is the material? Is it concrete or is it gypsum? Are these the same thing? Is one better than the other for candle use? This guide answers these questions definitively, explaining the material science behind Karessa's jar construction and why the specific gypsum-cement composite used in Surat production is the optimal material for candle jar applications in India.

What Is Gypsum?

Gypsum (calcium sulphate dihydrate, CaSO4·2H2O) is a naturally occurring mineral mined in powdered form from gypsum deposits. When gypsum powder is mixed with water, a chemical reaction occurs that causes it to set into a hard, rigid material — this is plaster of Paris (POP), the most common form of processed gypsum in India. Gypsum sets quickly (30-60 minutes), produces a smooth white surface, and is excellent for fine detail casting.

Pure gypsum has limitations: it is relatively brittle (can chip or crack under impact), has moderate heat tolerance, and absorbs moisture in very humid environments (Indian monsoon) if unsealed.

What Is Concrete?

Concrete is a composite material made from cement (calcium silicate compounds), aggregates (sand, gravel), and water. Portland cement concrete is the construction material — used in buildings, roads, and infrastructure. Architectural concrete for home decor uses a finer version with less aggregate — the result is the smooth, grey, slightly textured material you see in architectural planters, vases, and home decor objects.

Concrete is harder and more impact-resistant than gypsum but is heavier, takes longer to set (24-48 hours), and is more difficult to cast in fine-detail moulds.

Karessa's 'Concrete Gypsum' — The Optimal Composite for Candle Jars

Karessa's jars are not pure gypsum nor pure Portland concrete — they are a carefully formulated composite that combines gypsum's detail-casting ability and smooth surface finish with cement's structural strength and heat tolerance. The specific ratio is proprietary to JB Decor's manufacturing process, developed over multiple years of production optimisation.

This composite achieves: the fine surface detail that Karessa's ribbed, lotus, and shell designs require (from the gypsum component), the structural strength that prevents cracking during candle burning (from the cement component), the appropriate heat tolerance for soy wax candle temperatures (55-65 degrees at the jar walls), and a surface that accepts the water-based sealant that prevents moisture absorption.

Why 'Concrete Gypsum' Is the Right Name

'Concrete gypsum' accurately describes the composite material: it has the appearance and structural character of architectural concrete (grey, textured, heavy-looking) while incorporating gypsum for the casting precision and surface finish that Karessa's detailed designs require. Neither 'gypsum jar' nor 'concrete jar' alone fully describes the product. 'Concrete gypsum jar' is the correct and complete description.

Experience the optimal concrete gypsum composite for candle making at karessacandles.com/collections/concrete-candle-jars.