Lesson 7 – Part 3 Sometimes, your explosive train doesn’t misfire completely — It starts, but somewhere along the hole, the detonation wave dies out. This is a Cut-Off, and it’s just as dangerous. ⸻ 🔍 What causes a Cut-Off? – Poor continuity in the explosive column – Gaps between boosters or cartridges – Water degradation of explosives – Bad priming (wrong type or position) – Column collapse due to improper stemming or geological failure ⸻ ⚠️ Why is it dangerous? – You think the hole fired, but part of it didn’t – There could be unexploded explosive deep in the hole – Secondary blasting becomes extremely risky – Drill rigs hitting unexploded sections can cause fatal accidents – You lose performance: poor fragmentation and high oversize ⸻ 🛡️ How to prevent Cut-Offs: ✅ Use continuous explosive column — no gaps ✅ Ensure water-resistant explosives in wet holes ✅ Double-check booster placement and priming ✅ Proper stemming with suitable material and technique ✅ Avoid drilling in soft zones that collapse during loading ⸻ 🛠️ Field Practice: – Log all holes and match explosive types to hole conditions – After blast, inspect muckpile signs — look for signs of poor breakage – If a hole is suspicious, treat it like a misfire until confirmed otherwise ⸻ 🎯 Remember: A Cut-Off is a misfire in disguise. Just because it started doesn’t mean it finished. Treat it with the same caution — and plan to avoid it from the start.