Fuse Making

Part of Gunpowder and Explosives

Making fuses for controlled ignition of explosive charges.

Why This Matters

A fuse is the link between the blaster and the explosive charge. Without a reliable fuse, you have only two options: either touch fire directly to the charge (suicidal for anything larger than a firecracker) or use a long trail of loose powder (unreliable and dangerous in wind or rain). A proper fuse gives you control — a predictable delay between lighting and detonation that allows you to reach safety.

In a rebuilding civilization, fuses are not a luxury. They are the safety mechanism that allows blasting to be a viable engineering technique rather than a death sentence. Every mine shaft, quarry, and road cut depends on fuses that burn at a known rate, resist wind and moisture, and ignite the main charge reliably.

The three main types of fuses — slow match, quick match, and safety fuse — each serve different purposes. Understanding when to use each type and how to make them reliably is essential knowledge for anyone working with explosives.

Types of Fuses

Type	Burn Rate	Use Case	Reliability
Slow match	10-30 cm per hour	Lighting other fuses; portable fire source	Good in still air; poor in wind/rain
Quick match	Near-instantaneous	Firing multiple charges simultaneously	Very good when dry; poor when wet
Safety fuse	60-90 seconds per meter	Primary blasting fuse; timed delay	Excellent; wind/water resistant

Each type is covered in its own detailed article. This article covers the general principles of fuse-making and how to choose the right fuse for your application.

Core Principles

Consistency Is Everything

A fuse that sometimes burns fast and sometimes burns slow is worse than no fuse at all. If your safety fuse burns at 90 seconds per meter on one section and 30 seconds per meter on another, you cannot calculate a safe retreat time. Every step of fuse-making must prioritize consistency:

• Use the same materials for every batch
• Apply saltpeter solution at the same concentration
• Dry fuses under the same conditions
• Test every batch before use

The Combustion Chain

All fuses work on the same principle: a combustible material (cord, paper, or powder) treated with an oxidizer (saltpeter) to sustain combustion. The fuse must carry fire reliably from one end to the other. Any break in the combustion chain — a wet spot, an untreated section, a kink that cuts off air — means the fuse goes out and the charge does not fire.

Failed fuses create misfires. Misfires create the most dangerous situation in blasting: a live charge that you think did not fire, tempting you to approach and investigate. Never investigate a misfire for at least 30 minutes, and never attempt to remove or re-fire a misfired charge.

Materials

Cord Materials

The base material for most fuses is cotton or linen cord. The cord must be:

• Absorbent: It needs to soak up and retain the saltpeter solution
• Consistent diameter: Variations in thickness cause variations in burn rate
• Tightly twisted or braided: Loose fibers burn unevenly
• Free of oils or wax: These prevent saltpeter absorption (wax is added later, only for the outer coating of safety fuse)

Best materials: Three-ply cotton string (5-8 mm diameter), loosely braided linen cord, or hemp rope of consistent diameter.

Making cord from scratch: If manufactured cord is unavailable, spin cotton or linen fibers into yarn, then braid three strands together. The braid provides consistent structure and burn characteristics.

Saltpeter Solution

The standard treatment solution for fuse cord:

1. Dissolve saltpeter (potassium nitrate) in hot water at a ratio of 1 part saltpeter to 3 parts water by weight
2. Stir until completely dissolved — no crystals should remain
3. The solution should be warm when used (crystals precipitate in cold solution)

Gunpowder Paste

For quick match and safety fuse cores:

1. Mix finely ground gunpowder (meal powder) with water to form a thick paste
2. The consistency should be like thick paint — it must coat the cord evenly but not drip
3. Add a small amount of gum arabic or hide glue (5% by weight) to improve adhesion
4. Use immediately — the paste dries quickly

Making Slow Match

Slow match is the simplest type of fuse. It is a rope soaked in saltpeter solution that burns slowly without an open flame — just a glowing ember that creeps along the cord.

1. Cut cotton or linen cord into working lengths (1-2 meters)
2. Soak the cord in saltpeter solution for at least 24 hours
3. Remove and hang to dry completely (2-3 days in warm, dry air)
4. The finished slow match should have visible white saltpeter crystals on its surface

Burn rate: Approximately 10-30 cm per hour, depending on saltpeter concentration and cord diameter.

Use: Slow match is primarily an ignition source — a portable, windproof ember for lighting quick match or safety fuse. It is not used as a primary blasting fuse because its burn rate is too slow and variable.

Making Quick Match

Quick match burns almost instantaneously — fire races along its entire length in a fraction of a second. It consists of a cotton cord coated in gunpowder paste.

1. Prepare gunpowder paste as described above
2. Draw the cord through the paste, ensuring complete coating
3. Hang to dry
4. For true quick-match behavior, enclose the dried, coated cord in a paper tube. The tube confines the gases, creating a flash that races ahead of the burning front.

Without the tube: The coated cord burns rapidly but not instantaneously — perhaps 1-2 meters per second. With the tube, it burns at 10+ meters per second.

Use: Firing multiple charges simultaneously (all connected by quick match), or when immediate ignition is needed.

Making Safety Fuse

Safety fuse is the workhorse of blasting. It burns at a predictable rate regardless of wind, light rain, or orientation, providing a timed delay for the blaster to retreat.

1. Start with a core of fine cotton string (2-3 mm diameter)
2. Apply a thin, even coating of gunpowder paste along the entire length
3. Allow to dry partially (tacky but not wet)
4. Wrap the coated core tightly with cotton thread in a spiral, completely covering the powder layer
5. Apply a second coat of gunpowder paste over the thread wrapping
6. Allow to dry completely
7. Waterproof the outside by coating with melted beeswax, pine pitch, or tallow

Burn rate target: 60-90 seconds per meter (1-1.5 cm per second).

Testing and Calibration

Essential Step

Never use a fuse in a live blasting operation without testing a sample from the same batch first.

Burn Rate Test

1. Cut a precisely measured length of fuse (exactly 1 meter)
2. In a safe outdoor location, light one end and time the burn with a reliable timepiece
3. Record the burn time
4. Test at least three samples from each batch
5. If the times vary by more than 10%, the batch is inconsistent and should not be used for critical applications

Reliability Test

1. Cut several 30 cm lengths of fuse
2. Light each one and observe:
   • Does it stay lit through the entire length?
   • Does it burn evenly or sputter and skip?
   • Does it go out at any point?
3. Any fuse that fails to burn completely through is unreliable. Reject the batch or re-treat with additional saltpeter solution.

Wet Test (Safety Fuse Only)

1. Submerge a 30 cm length of safety fuse in water for 10 seconds
2. Remove, shake off excess water, and attempt to light
3. Properly waterproofed safety fuse should light and burn normally after brief immersion
4. If it fails, the waterproof coating is inadequate — recoat with wax or pitch

Connecting Fuse to Charge

The junction between fuse and charge is the most common failure point. If the fuse burns out without igniting the powder charge, the blast fails.

Best Practices

• Insert the fuse end at least 5 cm into the powder charge
• Ensure direct contact between fuse and powder — no gaps, no stemming material between them
• For cartridges, poke the fuse through the wrapper into the powder
• Tie or tape the fuse to the cartridge to prevent it pulling out during tamping
• Never cut the fuse short — always leave more length than you think you need

Fuse Length Calculation

For safety fuse with a tested burn rate of 90 seconds per meter:

• Determine retreat distance needed (at least 100 meters for surface blasting)
• Estimate retreat time (brisk walk on rough ground: 2 minutes for 100 meters)
• Add safety margin (50%): 3 minutes total
• Required fuse length: 3 minutes / 1.5 minutes per meter = 2 meters

Always round up. Always add extra length. There is no penalty for a fuse that is too long; a fuse that is too short can kill you.