Quick facts
- Products compared
- Polyester Clear Casting Resin (SPR 201 CC) · Clear Casting Resin (epoxy)
- Key point
- Same everyday name, different chemistries and different products
- Polyester cure
- MEKP + cobalt octoate, added separately
- Epoxy cure
- Resin + its own hardener, 2:1 by weight
One name, two different products
In workshops both are called “clear casting resin”, but they are different chemistries sold as different products. Polyester Clear Casting Resin (SPR 201 CC) is an orthophthalic unsaturated polyester. The Clear Casting Resin page on this site is a two-part epoxy system. When you enquire, name the product or its code, not just “casting resin”.
A polyester cures when a peroxide initiator starts the styrene cross-linking; SPR 201 CC is supplied non-accelerated and the catalogue’s reference cure is MEKP 1.5% with cobalt octoate 0.4%, each added separately and never mixed with each other directly. An epoxy cures by reacting with its own hardener in a set ratio — 2:1 by weight for this product — so accurate weighing matters more than catalyst percentage.
How to decide
First, keep the chemistry your process was developed on. A workshop that doses MEKP and cobalt, and makes statues, idols, decorative articles or furniture top coats, starts from SPR 201 CC. A workshop that weighs resin and hardener, and makes river tables, jewellery or deeper decorative castings, starts from the epoxy Clear Casting Resin, whose documentation gives casting depths up to 30 mm per pour, with deeper work built up in stages.
Second, look at the schedule. The polyester’s published gel time is under 8 minutes; the epoxy’s published initial cure is about 24 hours and full cure about 72 hours at 25 °C. Neither is right in general — the mould, section thickness and production rhythm decide which fits. Switching from one chemistry to the other needs a trial on your own mould.
What the data does not tell you
The published values do not state how clear a casting stays over time, how it behaves outdoors or in sunlight, or how strong it is in use. The catalogue does not publish a maximum pour thickness for SPR 201 CC. Colour, filler, section thickness and workshop temperature all change the result, so confirm the look and the cure with a trial piece before production.
Sources, roles and the Nepal enquiry path
SPR 201 CC values are the typical specification in the supplier’s 2026 product catalogue; no Technical Data Sheet for that grade has been published on this site. The epoxy Clear Casting Resin values are from its supplier Technical Data Sheet as recorded 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.
Polyester vs epoxy clear casting resin: decision table
| Criterion | Polyester Clear Casting Resin (SPR 201 CC) | Clear Casting Resin (epoxy) |
|---|---|---|
| Chemistry | Orthophthalic unsaturated polyester in styrene | Two-part epoxy system |
| Supply | Single liquid, non-accelerated | Resin supplied with its hardener |
| How it cures | MEKP 1.5% + cobalt octoate 0.4%, added separately | Resin and hardener mixed 2:1 by weight |
| Viscosity | 350–450 cPs | 900 cPs at 25 °C |
| Gel / cure time | Gel time under 8 minutes | Initial cure 24 hours, full cure 72 hours at 25 °C |
| Styrene content | 33–40% | Not listed |
| Other published values | None beyond the catalogue specification | Shore D 82 fully cured; shrinkage under 0.2%; up to 30 mm per pour |
| Listed uses | Statues and idols, decorative articles and artefacts, furniture top coats | River tables and wood-resin furniture, jewellery, decorative, art and industrial casting |
| Choose when… | Your process runs on MEKP and cobalt dosing and the piece is a listed polyester use | Your process is built around a weighed two-part epoxy and the piece is a listed epoxy use |
Sources: SPR 201 CC values from the supplier’s 2026 product catalogue; epoxy Clear Casting Resin values from its supplier Technical Data Sheet as recorded on this site. Typical values describe a grade; they are not batch guarantees or acceptance limits.
Frequently asked questions
Is SPR 201 CC the same product as the Clear Casting Resin page?
No. SPR 201 CC is an orthophthalic polyester; the Clear Casting Resin page is a two-part epoxy system with its own hardener.
Can I cure the epoxy with MEKP?
No. The epoxy cures with its own hardener at 2:1 by weight. MEKP and cobalt octoate are the cure system for the polyester grade.
Which one is better for casting?
Neither in general. Choose by your established process, the listed uses and the cure schedule your production can accept.
What about buttons?
Buttons have their own grade, SPR 201 BGR Button Grade Resin. The button-grade vs clear-casting comparison covers that choice.