Two bands in the catalogue
The 2026 catalogue gives SPR 301 RB two gel-time bands: ultra-fast grades at 15 seconds to 2 minutes, and delayed grades at 5 to 30+ minutes, both at the reference cure of BPO 7% with cobalt octoate approximately 0.4%, added separately. A compound maker enquiring about SPR 301 RB should state which band, or bands, the product needs.
Why anchoring uses different speeds
Resin anchoring products are designed around installation. Some need the resin to set almost as soon as the bolt stops spinning, so the bolt can be tensioned quickly. Others need time for insertion and positioning, or deliberately combine a fast-setting portion with a slower one so that part of the bond sets before the rest. The base-resin band follows that design.
Published typical values
| Property | Rock Bolt Grade Resin (SPR 301 RB) |
|---|---|
| Chemistry | Isophthalic unsaturated polyester |
| Viscosity (typical) | 2,000–3,500 cPs |
| Gel time / pot life (typical) | Ultra-fast grades 15 seconds–2 minutes · delayed grades 5–30+ minutes |
| Specific gravity / density (typical) | Approximately 1.12 |
| Styrene content (typical) | 35–39% by weight |
| Reference cure | BPO 7% + Cobalt Octoate approximately 0.4% — added separately during use |
| Source of values | 2026 catalogue; grade TDS |
Typical values, reproduced from each product’s own published data. They describe the liquid resin at its reference condition, not a finished part, and are not guaranteed limits.
What moves the set time
Peroxide cures are strongly temperature-dependent, so the same compound sets more slowly in a cold heading than on a warm test bench. Filler type and loading, initiator paste strength and the mixing achieved in the hole also change set time. That is why the bands describe the base-resin grades, and why the finished product must be tested at site temperatures.