Quick facts
- Grades compared
- SPR 201 RL · SPR 201 RL (UV)
- Shared chemistry
- Clear orthophthalic unsaturated polyester
- Main difference
- UV stabilization for sheets exposed to sunlight
- Decided by
- Sun exposure of the installed sheet and the sheet specification
What actually differs
Both grades are clear orthophthalic polyesters made for translucent roofing sheet, and both are supplied non-accelerated and cured with an MEKP initiator. The difference is the role: SPR 201 RL is the standard water-white roof-light and skylight resin, while SPR 201 RL (UV) is the catalogue’s UV-stabilized grade for roof-light sheets that will be exposed to sunlight.
Their published values overlap. The standard grade’s TDS gives single figures (280 cPs, 6.5 minutes, 35% styrene); the UV grade’s catalogue entry gives ranges (200–400 cPs, 6.5–10 minutes, 30–40% styrene). The numbers do not separate the grades; the intended exposure does.
How to decide
Start from where the finished sheet will be installed. If it will sit in direct sunlight for its service — an open roof, a daylighting panel on an exposed shed — and the buyer’s sheet specification calls for a UV-stabilized resin, specify SPR 201 RL (UV). If the sheet is sheltered, used indoors, or the specification does not ask for UV stabilization, the standard SPR 201 RL is the listed roof-light grade.
If the sheet should be yellow rather than clear, neither grade is the starting point: the pre-pigmented yellow sheet resins are a separate selection route, covered in the comparison of sheet-grade yellow resin and roof-light resin.
What the data does not tell you
Neither document publishes a weathering life, a yellowing rate or a light-transmission figure, and this guide makes no such claim. UV stabilization in the resin is one input; how a finished sheet performs outdoors also depends on its thickness, glass content, surface and installation, and on the site. If a project needs a stated outdoor performance, it has to be established by testing the finished sheet.
Sources, roles and the Nepal enquiry path
SPR 201 RL figures are taken from the supplier’s Roof Light Resin Technical Data Sheet as recorded on this site. SPR 201 RL (UV) figures are the typical specification in the supplier’s 2026 product catalogue; no Technical Data Sheet for that grade has been published on this site.
Samrat Poly Resins, India manufactures the grade and issues its technical information. Samrat FRP Traders is the Nepal supplier and importer and handles enquiries; price, packaging, lead time and stock in Nepal are confirmed on enquiry.
SPR 201 RL vs SPR 201 RL (UV): decision table
| Criterion | Roof Light Resin (SPR 201 RL) | UV-Stabilized Roof Light Resin (SPR 201 RL (UV)) |
|---|---|---|
| Chemistry | Orthophthalic unsaturated polyester | UV-stabilized clear orthophthalic polyester |
| Appearance | Water-white, unpigmented | Clear transparent liquid |
| Supply condition | Non-accelerated; thixotropy not stated | Non-accelerated; thixotropy not stated |
| Viscosity | 280 cPs | 200–400 cPs |
| Gel time | 6.5 minutes | 6.5–10 minutes |
| Styrene content | 35% | 30–40% |
| Reference cure | MEKP-catalysed, dosed per the TDS | MEKP 1.5% + cobalt octoate 0.4%, added separately |
| Listed uses | Roof-light panels, skylight sheets, greenhouse roofing, industrial and commercial roofing | UV-stabilized clear roof-light sheets, sunlight-exposed translucent roofing panels, industrial daylighting |
| Choose when… | The sheet is not installed in sustained direct sun, or its specification does not call for a UV-stabilized resin | The sheet will be installed in direct sunlight and its specification calls for a UV-stabilized resin |
Sources: SPR 201 RL values from the Roof Light Resin Technical Data Sheet (SPR-TDS-RLS) and this site’s product record; SPR 201 RL (UV) values from the supplier’s 2026 product catalogue. Typical values describe a grade; they are not batch guarantees or acceptance limits.
Frequently asked questions
Is the UV grade simply the better roof-light resin?
No. It is the grade listed for sheets exposed to sunlight. For sheltered or indoor sheet, the standard SPR 201 RL is the listed grade; the installation decides.
How many years will a UV-stabilized sheet last?
No weathering life is published for either grade. Outdoor life depends on the finished sheet and the site, and has to be established by testing the sheet.
Do the two grades cure differently?
Both are non-accelerated and MEKP-catalysed. The catalogue gives SPR 201 RL (UV) a reference cure of MEKP 1.5% with cobalt octoate 0.4%, each added separately; for SPR 201 RL follow its TDS.
Is either grade a yellow sheet resin?
No. Both are clear grades. Yellow sheet is made with the pre-pigmented sheet-grade yellow resins, which are separate products.