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Application guide

GP Yellow Resin for Roofing Sheet Manufacturing

GP Yellow Resin's transparent yellow, general-purpose orthophthalic base wets out reinforcement for corrugated FRP roofing sheets. For a factory-pigmented grade tuned specifically for sheet production instead, Sheet Grade Yellow Resin is the dedicated alternative.

General-purpose base for sheet lay-up.

Corrugated FRP roofing and cladding sheets are laminated in thin, wide sections, where resin has to wet out reinforcement evenly across a long run without leaving the dry patches that surface as cracks a few months later. GP Yellow Resin, Samrat FRP Traders' general-purpose orthophthalic laminating resin, can be used for this work with the same MEKP and cobalt octoate cure system as our GP Clear Resin — though its thicker body is worth weighing against dedicated sheet-grade options before choosing it for this specific job.

What manufacturers build

Roofing sheet manufacturers produce corrugated and flat FRP sheets in standard profiles for industrial roofing, cladding and daylighting panels, along with ridge caps, flashing pieces and ancillary fittings used to complete a roof installation. Sheet widths and corrugation profiles are typically standardised to match common steel roofing profiles.

Why this material suits the work

Because roofing sheets are laminated in thin, wide sections, wet-out speed and consistency matter more here than in a thicker structural laminate — any dry patch shows up quickly as a weak point under roof load or wind uplift. GP Yellow Resin's 450–600 cPs viscosity is thicker than GP Clear Resin's 350–450 cPs, which in turn is thicker than the purpose-built Sheet Grade Yellow Resin (around 280 cPs), a grade intended specifically for sheet and panel work. GP Yellow Resin can still be worked into a roofing sheet laminate with careful rolling to avoid dry patches, and its longer 10–15 minute gel time gives more time to do that across a wide sheet mould — but for fabricators prioritising minimum labour and dry-patch risk on thin sheet sections specifically, the lower-viscosity Sheet Grade Yellow Resin or GP Clear Resin are the better-suited starting point.

Required resin characteristics

  • Even wet-out across wide, thin sheet moulds despite a thicker body than a dedicated sheet-grade resin
  • A workable gel time to spread and roll resin through the corrugation profile before it sets
  • Reliable room-temperature cure so sheets can be demoulded on a predictable schedule
  • Adequate flexural strength for a thin laminate carrying roof loads and wind uplift
  • Batch consistency so sheet thickness and strength don't drift across a production run

Process context

Roofing sheets are laminated over a corrugated mould bed: chopped strand mat is laid into the corrugation profile and wet out with GP Yellow Resin, catalysed by an MEKP hardener and cobalt octoate accelerator, worked through with a roller to remove air and reach even thickness across every corrugation — its thicker body needs a little more rolling attention than a low-viscosity sheet-grade resin to avoid dry patches. Sheets cure at room temperature, often under a cover sheet to control surface finish, before being trimmed to length and stacked.

Advantages

  • Longer 10–15 minute gel time gives more time to roll resin evenly through a wide corrugated mould
  • Same non-accelerated MEKP/cobalt octoate cure system as GP Clear Resin
  • One documented grade suits the steady consumption of an ongoing sheet production run
  • Consistent 99% purity for predictable batch-to-batch processing

Common products

  • Corrugated FRP roofing sheets
  • Flat FRP cladding panels
  • Ridge caps and flashing accessories
  • Industrial shed and warehouse roofing systems

Common questions

Is GP Yellow Resin the best choice for FRP roofing sheets, or is a dedicated sheet-grade resin better?

For thin, wide roofing sheet sections specifically, a lower-viscosity resin reduces the labour needed to avoid dry patches. GP Yellow Resin (450–600 cPs) is thicker than GP Clear Resin (350–450 cPs), which in turn is thicker than the purpose-built Sheet Grade Yellow Resin (around 280 cPs). GP Yellow Resin can still be used for roofing sheets with careful rolling, but Sheet Grade Yellow Resin or GP Clear Resin are the better-suited starting point where minimising dry-patch risk on thin sections is the priority.

What is the difference between GP Yellow Resin and Sheet Grade Yellow Resin for roofing sheets?

GP Yellow Resin is a general-purpose grade also used for tanks, cooling towers and general lamination. Sheet Grade Yellow Resin is factory-pigmented and formulated at a lower viscosity specifically for sheet and panel production, making it the more purpose-built choice for roofing and cladding sheets.

What reinforcement is used for FRP roofing sheets made with GP Yellow Resin?

Roofing sheets are typically laminated with E-glass chopped strand mat, laid into the corrugation profile before resin is applied and worked through with a roller — the same reinforcement approach used with GP Clear Resin or Sheet Grade Yellow Resin.

How is GP Yellow Resin catalysed for roofing sheet production?

It is cured at room temperature with an MEKP catalyst (around 1.5%) and a cobalt octoate accelerator (0.3–0.5%), with dosage adjusted to suit ambient temperature and the pace of the production line — the same non-accelerated system used across Samrat FRP Traders' general-purpose grades.

Can GP Yellow Resin be pigmented for coloured roofing sheets, given it's already yellow-tinted?

Yes, though its existing yellow tint will combine with whatever pigment is added. For a fully controlled, factory-consistent colour across every sheet, Sheet Grade Yellow Resin's pre-pigmented formulation is the more predictable option.

Related products

GP Yellow Resin →MEKP Hardener →Sheet Grade Yellow Resin →GP Clear Resin →UV Stabilized Sheet Grade Yellow Resin →

Need GP Yellow Resin for your roofing sheet production?

Get a bulk quote for GP Yellow Resin, or talk to our technical team about whether GP Yellow Resin, GP Clear Resin or Sheet Grade Yellow Resin best suits your sheet lamination line.

Contact Samrat FRP Traders