Quick facts
- UPR on this site
- Standard clear UPR is published as GP Clear Resin for general FRP work
- Epoxy on this site
- Clear Casting Resin is a separately published two-part epoxy system
- Selection trigger
- The required product system, component and process
- Do not transfer
- Mixing, cure or TDS information between resin systems
Treat UPR and epoxy as separate published systems
A resin buyer may use the terms polyester resin and epoxy resin in the same conversation, but they should not be treated as interchangeable labels. This site publishes a standard clear UPR for general FRP work and a separate two-part epoxy product for clear decorative casting contexts.
The correct starting point is the required system and product role. If a drawing, process or customer requirement specifies an epoxy system, use the applicable epoxy product data. If the requirement is a general reinforced FRP laminate, begin with the published UPR product role instead.
Match the product role before comparing details
GP Clear Resin is published as the standard clear orthophthalic UPR grade for general FRP work with reinforcement. Clear Casting Resin is published as a separate epoxy system for clear decorative casting and deeper-pour casting contexts.
This role distinction is more useful than trying to compare isolated specifications across different systems. The relevant TDS and published application context should remain with the product being considered.
Keep the technical references separate
Do not transfer handling, curing, ratio or process assumptions from one resin system to another. The published technical data and applicable approved instructions for the selected product are the controlling reference.
Where a buyer is unsure whether the component requires a reinforced laminate, a surface layer, a decorative cast part or a specified system, document that question first and review the relevant product page before requesting a quotation.
Information to provide before selection
Share the component, whether reinforcement is involved, intended appearance or product role, process, expected quantity and delivery location. If an epoxy system is stated in the requirement, include that source document or wording for review.
Published system comparison
| Decision point | Standard UPR / GP Clear Resin | Clear Casting Resin |
|---|---|---|
| Published system | Orthophthalic unsaturated polyester resin | Separate two-part epoxy system |
| Published product role | General FRP work with reinforcement | Clear decorative casting and deeper-pour casting context |
| Technical reference | GP Clear Resin TDS | Clear Casting Resin TDS and its own published instructions |
| Selection rule | Use where the general FRP product role fits | Use only where the separate epoxy system and product role are relevant |
This guide is limited to the product systems published on this site. It does not claim that every UPR or epoxy product in the market is equivalent to these listed grades.
Frequently asked questions
Are the published UPR and epoxy products interchangeable?
No. The site publishes them as separate resin systems with different product roles and technical references. Use the relevant product TDS rather than transferring assumptions from one system to another.
Which product should be reviewed for reinforced general FRP work?
The published standard clear UPR, supplied as GP Clear Resin, is the general FRP starting point. Confirm the actual component and process against its product data.
Which product should be reviewed when an epoxy system is specified?
Review the separately published epoxy product information and applicable technical instructions. Do not substitute a polyester resin simply because both products are described broadly as resin.