Same job, different exposure
Both grades make translucent roof-light sheets from the same orthophthalic chemistry. The catalogue separates them by what the sheet faces: SPR 201 RL for translucent roof-light sheet, and SPR 201 RL (UV) where the roof-light sheet is exposed to sunlight.
Published typical values
SPR 201 RL publishes single values from its TDS; SPR 201 RL (UV) publishes catalogue ranges. Their processing is similar.
| Property | Roof Light Sheet Grade Resin (SPR 201 RL) | UV-Stabilized Roof Light Resin (SPR 201 RL (UV)) |
|---|---|---|
| Chemistry | Orthophthalic Unsaturated Polyester | Orthophthalic unsaturated polyester, UV-stabilized |
| Appearance | Water White | Clear transparent liquid |
| Viscosity (typical) | 280 cPs | 200–400 cPs |
| Gel time / pot life (typical) | 6.5 Minutes | 6.5–10 minutes |
| Styrene content (typical) | 35% | 30–40% |
| Reference cure | MEKP 1.5% + cobalt octoate 0.4% | MEKP 1.5% + Cobalt Octoate 0.4% — added separately during use |
| Source of values | Roof Light Sheet Grade Resin TDS | 2026 catalogue; grade TDS |
Typical values, reproduced from each product’s own published data. They describe the liquid resin at its reference condition, not a finished part, and are not guaranteed limits.
What UV stabilisation changes
UV stabilisation targets the sunlight degradation that yellows and erodes a sheet’s surface. It does not change how the resin is laminated or cured, and it is not UV curing. It also cannot compensate for poor glass wet-out, a thin resin surface or incomplete cure, all of which shorten a sheet’s outdoor life whichever grade is used.
Deciding
Choose by the sheet’s exposure. For sheets in direct sun, start with RL (UV); for shaded, indoor or short-life panels, RL may be enough. If the sheet’s buyer names a weathering or light-transmission requirement, test the finished sheet against it.