Contents
1. What decorative polyurethane covers
Decorative polyurethane is the rigid PU foam family used for architectural ornament: cornices (kartonpiyer — the profile that runs along the wall-ceiling joint), ceiling medallions (tavan göbeği — the ornament that frames a chandelier mount), columns and capitals, door and window frames, wall panels, baseboards and chair rails, and the wide range of small profiles that finish an interior. The same product family also appears in exterior trim, sign substrates and stage and film production.
The unifying property is the combination that ornament needs: low weight (so a cornice can be glued to a wall instead of mechanically anchored), sharp detail retention (so the profile carries fine moulded edges and texture), paintability (so the finished part can be painted or gilded to any specification), and dimensional stability under indoor humidity changes. Rigid PU foam at decorative density delivers all four, which is why it has become the dominant material in the segment over the past three decades.
2. The rigid PU system behind a decorative part
A decorative polyurethane part is much denser than an insulation panel core. Insulation-grade rigid PU runs at roughly 35–60 kg/m³; decorative PU typically sits at 200–350 kg/m³ for cornices and medallions, and 300–500 kg/m³ where higher mechanical strength or a deeper integral skin is needed (columns, exterior trim, sign substrates). The formulation is tuned for a fine, closed-cell structure — the foam has to carry sharp moulded edges without surface defect — and for fast demould, because the cycle economics of a casting line depend on how quickly the part can come out of the mould.
An integral skin is typical on the visible surface: a denser, more polymer-rich layer 0.5–2 mm thick that forms automatically against the mould wall during cure, producing a smooth, primed surface ready to paint with minimal preparation. Underneath, the bulk of the part is the lower-density foam core that drives the weight advantage. Catalysts, surfactants and where required flame retardants in the polyol blend tune cell size, demould time and fire behaviour against the application's requirements.
3. Production routes — open mould, closed mould, hand cast vs automated
Open mould casting is the dominant route for long, linear parts like cornices and baseboards. The mould — typically a long silicone elastomer cavity supported by a rigid backing — sits open on a casting table; the PU mix is poured into it from a low-pressure machine or, on shorter runs, by hand from a pre-weighed cup; the foam rises and self-levels in the mould; demould happens after the cure time of the system (typically 6–20 minutes). The mould then receives release agent and the next cast cycle starts. This route handles the largest portion of the cornice market because the parts are linear and the moulds are inexpensive to build.
Closed mould casting is used for three-dimensional parts: ceiling medallions, capitals, complex profiles and rosettes where the moulded surface is on more than one face. The mix is poured or injected into a closed mould with vents that let air and any rising foam expansion escape. Closed moulds are heavier and more expensive to build but produce parts with all-around surface detail and a more uniform skin.
Hand cast vs automated. Hand casting — operator pre-weighs the polyol and isocyanate, mixes, pours — is economical for short runs, custom geometry, prototyping and small workshops; the per-part labour is high but the equipment cost is near zero. Automated low-pressure dispensing — a metering machine handles the ratio and dispenses into the mould — pays back at higher volumes by removing batch-to-batch variation and freeing operators from the mixing step. The decorative segment runs a mix of both, often inside the same plant.
4. Why polyurethane displaced plaster and wood
The traditional materials each have a real disadvantage that PU addresses cleanly. Plaster (alçı) is heavy — a 2-metre cornice in plaster can weigh ten times more than the same profile in PU — which makes handling and installation labour-intensive, and it is brittle, so transport breakage is significant. It is also dimensionally unstable in humid environments. Wood is dimensionally unstable too (cornices crack or open at joints when humidity swings), expensive when the profile needs to be carved or routed with detail, and limited in geometry by what a router or moulder can produce.
PVC and HDF profiles are sometimes used at the lower end of the market but cannot match the depth of detail or the moulded-in surface texture that PU casting gives. The product looks plastic; the profile is limited to what an extrusion die can produce.
Polyurethane resolves the trade-off: a finished cornice that weighs 0.3–0.8 kg per metre, installs with construction adhesive on standard interior walls, takes a primer-paint or gilded finish indistinguishably from plaster, holds sharp Greek-key, leaf or rosette detail down to sub-millimetre features, and tolerates the humidity cycle of any normal interior. For exterior trim in mild climates, the closed-cell, dense PU also handles moisture in a way wood and plaster never could.
5. Market position, standards and finishing
Türkiye is one of the global production hubs for decorative polyurethane — a combination of strong domestic furniture and interior-finish demand, an export footprint into Russia, the Caucasus, the Middle East and parts of Africa, and a cluster of converters experienced in the casting craft. The market is fragmented between catalogue producers running standard cornice and medallion profiles at scale and bespoke workshops handling project-specific ornament for restoration, hotel and high-end residential interiors.
Fire performance matters most for ceiling applications and any installation governed by a building code. Decorative PU systems can be formulated to a B-s2,d0 reaction-to-fire class under EN 13501 with the right flame retardants; the foam is closed-cell and the surface integral skin both help. For installations where the code mandates a higher class (A2 or B-s1) the converter will typically combine PU with a mineral surface treatment or specify a different material.
Finishing. The integral skin produced by closed-cell rigid PU is a primer-ready surface in most cases — a light sanding, a single coat of acrylic primer and the part takes acrylic, oil-based, metallic or gilded finishes equally well. For glossy finishes a second primer-sand cycle gives the depth a high-end interior expects. Many catalogue producers ship parts pre-primed (white or off-white) so the installer's painter only handles the topcoat.
Regulatory side is the standard polyurethane frame: REACH and SVHC declarations for European-bound shipments, KKDIK for domestic distribution in Türkiye, documented user training for products above 0.1 % free diisocyanate when applicable. The system house provides TDS and MSDS documentation for the formulation; the finished decorative part is governed by the construction-product framework at the installation point.