Ground Ignition Methods for Slash Pile Burning: A Comparative Field Evaluation

The Technical Challenge of Slash Pile Ignition

Slash pile burning is the controlled combustion of leftover tree branches, brush, and woody debris whichis a routine part of forestry, logging, and land management operations. Piles are typically burned during a narrow seasonal window when weather, fuel moisture, and permitting conditions align, so a crew's ability to ignite a pile reliably and safely has a direct effect on how much ground they can cover in that window.

Ignition becomes substantially harder when fuel is wet, snow-covered, or otherwise below the moisture level needed for sustained combustion. Wet or snow-packed wood needs more sustained heat before it reaches a high enough temperature to sustain its own flame. Under these conditions, traditional ignition methods — hand-built kindling fires and liquid-fuel torches — often require multiple attempts, extra labor, and closer monitoring to avoid a partial burn that leaves a pile smoldering instead of fully consumed.

Liquid ignition fuels add another consideration. Fuel that is poured or sprayed onto a pile can run off the surface and soak into the surrounding ground, which creates a secondary fire-risk area or a potential source of soil contamination. Because these fuels burn off quickly, they also may not deliver enough sustained heat to carry ignition through to established combustion in wet material, increasing the odds a crew will need to reignite the pile.

An Alternative Approach: Gelled Alcohol Fire Starters

One alternative to kindling and liquid-fuel, such as gasoline or kerosene, is a contained, gelled-fuel ignition source. FireSlug®, developed by Forrest Technical Coatings for forestry, logging, and other ground-ignition applications, is an alcohol-based gel fuel sealed inside a small plastic pouch (known in the industry as a “blivet”).

Two design characteristics distinguish this approach from traditional kindling or liquid fuel torches:

Fuel containment. Because the gelled alcohol blivet is a non-toxic fire starter and the fuel is contained, it reduces the concerns associated with liquid fuels that can spill, run off, or soak into the surrounding ground.
Sustained burn duration. A single blivet burns for approximately 30 minutes once ignited. That extended burn time gives the slash pile more time to reach ignition temperature than a brief flare from loose kindling or a torch flame removed after use — a meaningful difference for wet or snow-packed wood, which needs more heat exposure to catch and hold a flame.

Each unit is also small and lightweight enough for one crew member to carry in volume, which matters on operations that involve igniting many piles across a work site in a single day.

Field Evaluation: Comparing Three Ignition Methods

FORESTNET, an independent forestry industry publication, conducted a third-party field demonstration comparing three ignition methods under matched conditions: hand-built kindling, a propane torch, and gelled-fuel blivets. The demonstration included a stress test in which a gallon of water was poured over a pile immediately before ignition, simulating a rain-soaked slash pile.

Method	Setup required	Performance on wet fuel	Heat source after initial ignition
Kindling	Splitting wood and hand-building a fire lay	Wet wood is difficult to ignite and slow to sustain a flame	None once the starter fire burns down; must be tended manually
Propane Torch	Transporting a torch and tank (roughly 20 lb) between piles	Effective while the torch is actively applied	None remains in the pile once the torch is withdrawn
Gelled-fuel blivet	Placed directly into the pile; no additional equipment	Continued burning and igniting surrounding material after a gallon of water was poured over the pile	Approximately 30 minutes of sustained heat from the unit itself

In the wet-pile test, the gelled-fuel blivet sustained combustion longer than either the kindling or the propane torch under the same conditions.

Testing and Applicable Use Cases

FireSlug® was evaluated at the U.S. Forest Service testing facility in Missoula, Montana, as part of its development for ground-ignition applications. Ignition products in this category are relevant to a range of use cases, including controlled burns, slash pile disposal, logging operations, forestry and agricultural land management, restoration work, and emergency fire management.

Takeaways for Crews Evaluating Ignition Methods

The comparative results point to a broader principle for any crew choosing an ignition method for wet or cold-weather conditions: the deciding factor is often not how hot or how large the initial flame is, but how long a heat source stays in contact with the fuel after ignition. A method that delivers a short, intense flame (a torch) or a labor-intensive but short-lived flame (kindling) can struggle against moisture in a way that a sustained, contained heat source is better positioned to overcome. Crews working in wet, snowy, or otherwise marginal burn conditions may want to weigh ignition duration and fuel containment — alongside cost, weight, and portability — when selecting an ignition method for their operation.

Product reference: FireSlug® Slash Burner,Forrest Technical Coatings.

(forrestpaint.com/product/fireslug-slash-burner)