Surface Veil, UV and Fire Resistance

What does the surfacing veil do?

During pultrusion a thin veil layer is laid on the very outside of the section. It is not a coating applied afterwards; it cures together with the resin during production and becomes part of the structure. The result is a smooth, resin-rich skin on the outside where fiber does not break through.

• It reduces fiber bloom: it delays fiber ends appearing at the surface over time — the benefit you notice most on handrails and platforms people touch.
• It is the first barrier: moisture and chemicals meet this resin-rich layer first, which makes reaching the body harder.
• It protects the surface against UV: it delays the sun acting directly on the fiber-resin interface.
• Appearance and cleaning: it gives a smoother surface that can be cleaned and, if needed, painted.

The veil does not replace the resin decision; it completes it. If the environment is chemically heavy, the right resin has to be chosen — see Resin Systems.

UV resistance, color fade and outdoor life

The same things happen to any polymer surface in constant sun: gloss drops, color lightens and a fine chalky layer forms on the surface. This is usually a surface phenomenon; it does not change the load capacity of the profile overnight, but it does affect appearance and surface quality.

• UV stabilized resin: it slows the degradation; the first choice for outdoor work.
• Surface veil: it separates the layer taking the hit from the body.
• Color choice: fading shows sooner on dark, saturated colors; lighter tones hide it better over time.
• Orientation and location: hours of sun, sea salt and dust loading affect life directly — the same profile does not age the same way on two different sites.
• Maintenance: regular cleaning and, where needed, a suitable topcoat keep the appearance for a long time.

This is why giving a single number for "how many years will it last" would not be honest. Describe the site and the expectation; we will settle the resin, additive and surface combination against the environment together.

Fire performance and flame spread

Let us be plain: composite is not a non-combustible material. But with flame retardant additives in the resin, flame-retardant behavior can be achieved. In practice that means:

• Ignition gets harder: more heat is needed for the material to catch.
• Flame spread slows: the speed at which flame travels across the surface drops.
• It self-extinguishes: once the flame source is removed, burning is designed not to sustain itself.
• Smoke and toxicity are a separate heading: some projects call for smoke density on top of flame behavior; that is a separate additive and resin decision.

On work with a fire requirement, what decides things is the test method and classcalled for in the specification. Because that varies from project to project we do not name a class here; send us your specification and we will tell you plainly which resin option we can meet it with. If we cannot meet it, we say so up front.

A short selection guide

• Enclosed, dry, out-of-sight structural member: a standard surface is usually enough.
• Anywhere people touch: add a surface veil — the difference in comfort and appearance is large.
• Outdoors, in constant sun: UV stabilized resin plus a surface veil.
• Chemical or salty environment: first move up the resin family, then talk about the surface — resin systems.
• There is a fire specification: an option with flame retardant additives; share the specification up front.
• If you are designing a structural member: whatever you decide about the surface, the section and deflection calculation need discussing too — mechanical properties and load capacity.

For the general logic of the material see What Is a GRP Profile?; for section options see the profile pages .