Slow Match

Part of Gunpowder and Explosives

Making slow match — a saltpeter-treated cord that carries a reliable, wind-resistant ember for igniting fuses and charges.

Why This Matters

Before matches, lighters, and electric igniters, slow match was the universal method for carrying and applying fire. A properly made slow match holds a glowing ember that creeps along the cord at a few centimeters per hour, requiring no fuel, no attention, and no shelter from moderate wind. It stays lit for hours, can be carried safely, and can ignite a fuse or priming charge with a simple touch.

For a rebuilding civilization working with explosives, slow match serves two critical roles. First, it is a portable fire source for the blaster — a way to carry a reliable ignition point to the blast site without the risk of an open flame near powder and fuse. Second, it is the ignition device itself: touching the glowing tip of a slow match to a safety fuse is the standard method for firing a charge.

Slow match is also remarkably simple to make. It requires only two materials — cotton or linen cord and a saltpeter solution — and the process takes less than a day of active work. Given that saltpeter is already your primary gunpowder ingredient, slow match production adds minimal cost to your explosives program.

The Chemistry

Slow match works because of the same chemistry that makes gunpowder: saltpeter (potassium nitrate) is an oxidizer that provides oxygen to sustain combustion. When cotton or linen cord is saturated with saltpeter, the cord does not need atmospheric oxygen to burn — it carries its own oxygen supply within the saltpeter crystals embedded in its fibers.

This means slow match burns in conditions that would extinguish an ordinary flame:

• In moderate wind (the cord is smoldering, not flaming, so wind cannot blow it out)
• In light rain (the saltpeter inside the cord is partially protected from surface moisture)
• Face-down (gravity does not affect the ember’s progress)
• In enclosed spaces (it needs no air supply)

The burn rate depends on the saltpeter concentration, the cord material and diameter, and how tightly the cord is twisted.

Materials

Cord Selection

The cord must be made of natural cellulose fiber — cotton or linen (flax). These materials char rather than melt, forming a coherent ash that carries the ember forward. Synthetic fibers, wool, and silk are not suitable.

Cord Type	Suitability	Notes
Cotton rope (3-ply, 5-10 mm)	Excellent	Most common choice; widely available
Linen cord (3-ply, 5-10 mm)	Excellent	Burns slightly slower than cotton
Hemp rope	Good	Coarser fiber; works but less consistent
Jute twine	Fair	Burns unevenly; use only if nothing else available
Wool, silk, synthetic	Not suitable	Melt, shrink, or fail to hold ember

Diameter matters: Thicker cord (8-10 mm) burns more slowly and holds a larger ember that is harder to extinguish accidentally. Thinner cord (3-5 mm) burns faster and is more fragile. For general use, 5-8 mm diameter is ideal.

Construction matters: Three-ply twisted rope is preferred over braided cord. The spiral twist channels air along the burning front and provides consistent density. Loosely twisted rope burns faster; tightly twisted rope burns slower.

Saltpeter Solution

The standard soaking solution:

• Concentration: 1 part saltpeter to 3-5 parts water by weight
• Higher concentration (1:3) = faster burn rate, more reliable ignition, but consumes more saltpeter
• Lower concentration (1:5) = slower burn rate, more economical, but less reliable in damp conditions

Preparation:

1. Heat water to near boiling (saltpeter dissolves much faster in hot water)
2. Add saltpeter gradually, stirring until completely dissolved
3. No undissolved crystals should remain — they cause uneven treatment
4. Allow the solution to cool to handling temperature before soaking the cord

Saltpeter Quality

Use the best-quality saltpeter available for slow match. Impure saltpeter (containing calcium nitrate or common salt) produces match that smolders unreliably or absorbs moisture and goes out. If your slow match is unreliable, the first thing to check is saltpeter purity.

Optional Additives

Some traditional formulations add small amounts of other materials:

Additive	Purpose	Amount
Lead acetate (“sugar of lead”)	Promotes smooth, consistent combustion	5% by weight of solution
Potassium carbonate (wood ash lye)	Slows burn rate	2-5% by weight
Gum arabic	Helps saltpeter adhere to fibers	1-2% by weight

Lead acetate is toxic and should be used with caution if at all. For most applications, plain saltpeter solution produces adequate slow match.

Manufacturing Process

Step 1: Prepare the Cord

1. Cut cord into working lengths of 1-3 meters (longer pieces are harder to handle during soaking)
2. If the cord is new and stiff, boil it in plain water for 30 minutes to remove any sizing, oils, or finishes
3. Rinse in clean water and allow to drain (but not dry completely)

Step 2: Soak in Saltpeter Solution

1. Place the prepared cord in a trough, bucket, or basin
2. Pour the warm saltpeter solution over the cord until fully submerged
3. Push the cord under the surface and work it with your hands to ensure the solution penetrates the center of the cord
4. Soak for a minimum of 12 hours; 24 hours is better

Coverage: Use enough solution to fully submerge all cord with at least 2 cm of liquid above the top layer. If cord is piled, it should all be wetted evenly.

Step 3: Dry

1. Remove the cord from the solution (do not rinse — you want the saltpeter to remain in the fibers)
2. Hang the cord in a warm, dry, well-ventilated area
3. Space individual pieces so they do not touch (touching pieces dry unevenly)
4. Drying time: 24-48 hours depending on humidity and temperature
5. The cord is fully dry when:
   • It feels stiff and slightly heavier than untreated cord
   • Bending it produces a slight cracking sound
   • White saltpeter crystals are visible on the surface and between the rope strands

Step 4: Second Treatment (Optional but Recommended)

For more reliable slow match, repeat the soak-and-dry cycle:

1. Re-soak the dried cord in fresh saltpeter solution for another 12-24 hours
2. Dry again as before
3. Double-treated cord has more saltpeter penetration and burns more reliably, especially in damp conditions

Testing

Basic Burn Test

1. Cut a 30 cm piece of finished slow match
2. Light one end with a flame (candle, small fire, or another slow match)
3. Once the ember is established (glowing red, no open flame), time the burn
4. It should burn at approximately 10-30 cm per hour (1-5 mm per minute)
5. The ember should progress steadily with no stops, flare-ups, or sections that burn through too quickly

Wind Test

1. Light a piece of slow match outdoors on a moderately windy day
2. The ember should continue smoldering despite wind
3. If the wind extinguishes it, the saltpeter concentration is too low — re-treat with a stronger solution

Hanging Test

1. Light a piece of slow match and hang it vertically
2. The ember should burn downward (against gravity) at a steady rate
3. If it goes out when hanging, the saltpeter concentration is too low

Ignition Transfer Test

1. Light a piece of slow match and allow the ember to establish fully
2. Touch the glowing tip to the end of a safety fuse
3. The fuse should ignite within 2-3 seconds of contact
4. If the slow match cannot ignite a safety fuse, it is too weak for use — re-treat or remake

Using Slow Match

Lighting Slow Match

Slow match can be lit from any flame source:

• Touch the end to a candle, campfire, or torch
• Hold it in the flame until 1-2 cm are glowing red
• Once the ember is established, blow gently on it to spread the glow
• The initial flame will die out, leaving a smoldering ember that creeps along the cord

Carrying Slow Match

Historical soldiers and miners carried slow match in one of several ways:

1. Coiled: Wind the match loosely around the hand or arm with the glowing end free. The coil keeps the match manageable and allows easy access to the ember.

2. In a matchbox: A perforated tin or wooden box that holds the coiled match. Perforations allow enough air for the ember to continue smoldering. The box protects the match from rain and accidental contact.

3. On a forked stick: Clamp the match in a forked stick (a “linstock”) so the glowing end is at arm’s length from your body. This is the traditional method for artillery crews and blasters.

Igniting a Fuse

1. Hold the slow match so the glowing ember is at the tip
2. Blow on the ember gently to bring it to bright red-orange heat
3. Press the ember firmly against the end of the safety fuse for 2-3 seconds
4. Look for sparks and smoke from the fuse — confirmation that it has caught
5. Once the fuse is burning, move the slow match away and begin retreat

Verify Ignition

Always verify that the fuse is actually burning before retreating. A fuse that appeared to light but actually did not creates a misfire — the most dangerous situation in blasting. Look for smoke and sparks traveling along the fuse for at least 2-3 seconds.

Extinguishing Slow Match

When you are done with a piece of slow match:

1. Pinch the ember between wet fingers (dip your fingers in water first)
2. Or press the ember against a wet stone or damp cloth
3. Verify that no ember remains — check for any glow or smoke
4. Never assume a slow match is out without checking — smoldering sections can re-ignite

Storage

• Store dried, unlit slow match in sealed containers (wooden boxes, stoneware jars) to prevent moisture absorption
• Keep away from any flame or heat source
• Do not store with loose gunpowder or other explosive materials
• Shelf life: 6-12 months if kept dry; inspect and test before use
• Signs of degradation: saltpeter crystals falling off (moisture has dissolved and re-deposited them unevenly), musty smell (mold), soft or limp texture (moisture absorption)
• Re-treat degraded slow match with fresh saltpeter solution or discard and make new

Troubleshooting

Problem	Cause	Solution
Match will not light	Too damp; insufficient saltpeter	Re-dry; re-soak in stronger solution
Match flares up with open flame	Too much saltpeter; very fine, loose cord	Use weaker solution; use tighter-twisted cord
Ember goes out after a few minutes	Saltpeter concentration too low; cord too thick	Re-treat; use thinner cord
Burns too fast (disappears in minutes)	Cord too thin; solution too strong	Use thicker cord; dilute solution
Uneven burn rate (fast/slow patches)	Uneven soaking or drying	Soak longer; rotate cord during drying
Generates sparks or pops	Impurities in saltpeter	Recrystallize saltpeter before making solution