Quick facts
- Catalogue code
- SPR 401 FRGC
- Chemistry
- Thixotropic terephthalic fire-retardant gelcoat
- Colours
- White, grey or custom colour
- Orthophthalic counterpart
- SPR 201 FR-GC
What the grade is for
SPR 401 FRGC is a thixotropic terephthalic fire-retardant gelcoat, described in the catalogue as having strong mechanical properties, for the mould-face surface of fire-retardant FRP components. Listed uses are fire-retardant gelcoat surfaces for rail and transport composite components, automotive composite components and fire-retardant moulded FRP parts.
Reading the viscosity pair and thixotropic index
The catalogue lists an opaque, thick pigmented liquid with a viscosity of 12,000–18,000 cPs at 2 rpm and 2,000–3,500 cPs at 20 rpm, and a thixotropic index of 4.5–6.0 — a gelcoat that thins when brushed or sprayed and stands on the mould face at rest. It also lists a gel time of 12–22 minutes at 25 °C, a density of 1.25–1.45 g/cm³ and 28–35% styrene by weight, supplied non-accelerated and thixotropic with a reference cure of MEKP 1.5% and cobalt octoate 0.4%, each added separately.
Limitations and alternatives
A fire-retardant gelcoat is one layer of a fire-retardant part. The catalogue’s guidance is to pair it with the fire-retardant laminating resin of the same project. Fire performance belongs to the finished, tested part and the requirement the project must meet; no fire rating is claimed for the gelcoat on its own.
The orthophthalic SPR 201 FR-GC is the other fire-retardant gelcoat in the range. The two publish viscosity at different measurement conditions, so their figures are not directly comparable; the comparison guide explains how to choose.
Source, roles and the Nepal enquiry path
The values on this page are the typical specification printed for SPR 401 FRGC in the supplier’s 2026 product catalogue. Samrat Poly Resins has since published a Technical Data Sheet for this grade, linked from the product page; its figures and the catalogue’s agree, and the catalogue is the source named beside every figure here.
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.
Key properties
| Property | Typical value |
|---|---|
| Appearance | Opaque, thick pigmented liquid |
| Colour | White, grey or custom colour |
| Viscosity — 2 rpm | 12,000–18,000 cPs |
| Viscosity — 20 rpm | 2,000–3,500 cPs |
| Thixotropic index | 4.5–6.0 |
| Gel time | 12–22 minutes at 25 °C |
| Density | 1.25–1.45 g/cm³ |
| Styrene content | 28–35% by weight |
| Supply condition | Non-accelerated · thixotropic |
| Reference cure system | MEKP 1.5% + Cobalt Octoate 0.4% — added separately during use |
Source: Samrat Poly Resins, India — product catalogue, 2026 edition (typical specification). Typical values describe the grade; they are not batch guarantees or acceptance limits.
Frequently asked questions
Does SPR 401 FRGC make a part fire-rated?
No. It is the surface layer; the finished part, its laminate and its testing against the project’s requirement decide fire performance.
What colours are listed?
The catalogue lists white, grey or custom colour. Confirm the colour you need when you enquire.
What does a thixotropic index of 4.5–6.0 mean?
The gelcoat is much thicker at rest than when worked, which helps it hold on a vertical mould face without running.