Density in PU is a real specification, not marketing. It determines how the profile holds its shape, how it takes a finish, and how it behaves on the wall over years.
Low-density PU (under 100 kg/m³) is soft. It ships cheaply, takes a finish with very fine detail because the mold fills easily, and is the right answer for highly ornate profiles that need every curve to come out sharp. The trade-off is the material is more vulnerable to impact and can dent in transit if not packed carefully.
Medium-density PU (100 to 200 kg/m³) is the standard for most cornice profiles. A reasonable balance of detail, weight, and impact resistance. The right answer for residential cornice in most rooms.
High-density PU (200 to 400 kg/m³) is heavier, harder, and more dimensionally stable. The right answer for commercial projects, high-traffic areas, baseboards that get kicked, and any application where the trim is likely to take abuse. The finish is slightly less crisp at the very fine details because the material is stiffer, but for most cornice profiles the difference is invisible.
Above 400 kg/m³, you're in the realm of structural PU, which is a different product category altogether.
For foreign-trade buyers, density should be in the spec sheet alongside the profile drawing, the length, and the finish. A factory that publishes density and can show you the test method (typically ASTM D1622 or equivalent) is a factory that has its quality system in order. A factory that doesn't mention density is one to ask questions of.
A practical observation from the field: high-density cornice installs slightly differently. The adhesive bond is fine, but the finish nails need to be pre-drilled in harder profiles, or the material can crack near the nail head. A small detail, but worth knowing in advance.
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Frequently Asked Questions
Q: What is High density crown molding?
A: High Density Crown Molding: Durability and Precision Explained is a high-density polyurethane (PU) cornice moulding produced by injection molding. It delivers the period-correct look of plaster cornice at a fraction of the weight, arrives factory-primed and paint-ready, and is 100% waterproof — making it suitable for living rooms, bedrooms, hotels, and covered exterior applications.
Q: How do you install High density crown molding?
A: Cut High density crown molding with a fine-tooth miter saw (40+ teeth), apply polyurethane construction adhesive such as PL Premium in a zigzag pattern, and press firmly against a primed wall/ceiling joint. Tack with finish nails while the adhesive cures. Mitre joints at inside and outside corners, fill with lightweight spackle, sand smooth, and finish with two coats of interior latex paint.
Q: Can PU cornice moulding be used in bathrooms and kitchens?
A: Yes. PU cornice is a closed-cell polymer and is fully waterproof — it will not swell, warp, or encourage mildew the way MDF or softwood does. For full-splash zones (above a shower), seal the back of the profile with a thin bead of silicone during installation to prevent moisture wicking from the substrate.
Q: What is the typical lead time and MOQ for High density crown molding?
A: Stock profiles of High density crown molding typically ship within 7–15 days from our Dongguan factory in standard 2.0–2.4 m lengths. MOQ is usually 200 linear meters per profile per shipment. Custom profiles require new tooling (25–35 days) and a 500 m MOQ. Free samples are available with freight collect.