How much dry chlorine and brake fluid does it take to start a fire
Executive summary
Mixing granular pool chlorine (calcium hypochlorite) with polyethylene‑glycol‑based brake fluid produces a vigorous, often explosive exothermic reaction that can produce a “fierce fireball”; laboratory demonstrations use on the order of grams of chlorine and milliliters of brake fluid to produce a brief but violent flame (example: 2–2.5 g chlorine and ~1 mL brake fluid) [1]. Multiple technical summaries and reports warn the combination is dangerous and has caused accidental and criminal explosions; detailed safe‑handling guidance and quantitative thresholds beyond small lab demos are not provided in the available sources [2] [3] [4].
1. What the chemistry does: powerful oxidation, not ordinary combustion
Calcium hypochlorite in pool “shock” serves as a strong oxidizer that can strip hydrogen and fragment organic molecules in brake fluid (glycol ethers or polyethylene glycols), producing hot, oxidized decomposition products that rapidly release heat and flame — the core mechanism behind the fireball observed when the materials are mixed [4] [5]. Sources describe this as an oxidizer + fuel improvised explosive: the oxidizing calcium hypochlorite rapidly oxidizes the brake‑fluid organics, producing a spontaneous, high‑temperature reaction rather than ordinary ignition of a flammable liquid alone [1] [4].
2. How much it takes: lab demos use tiny amounts, but real thresholds are not fully specified
Published laboratory demonstrations and safety write‑ups recommend micro‑scale amounts — for instance, placing roughly 2–2.5 grams of swimming pool chlorine in an open evaporating dish and adding about 1 mL of brake fluid produces a fireball that flares and dies quickly, and may shatter glass [1]. Official abstracts and reports emphasize that granular pool chlorine and brake fluid “react violently” and have produced fierce fireballs in multiple incidents, but they do not provide comprehensive mass/volume thresholds for household‑scale or larger explosions [2] [3].
3. Evidence of hazard: documented in government and journalistic reports
An Office of Justice Programs abstract and related technical summaries assert that granular calcium hypochlorite and polyethylene glycol brake fluid “react violently” and produce fierce fireballs; reporting notes these mixtures have occurred in accidental and criminal explosions and that research cannot get the brake fluid to ignite on its own without the oxidizer [2] [3] [4]. Popular science and demonstration coverage (e.g., Sciencing, SolidSmack) reproduce the lab procedure and reiterate that the reaction is dangerous, can shatter glass, and should be done only by experts in controlled settings [5] [1].
4. Safe handling and research context: controlled, expert‑only demonstrations
Sources uniformly warn the experiment is dangerous and recommend that any demonstration be done in a laboratory with a fume hood, expert supervision, appropriate face shields, and tiny quantities — or not at all outside controlled conditions [1]. Gizmodo and other coverage emphasize that although the heat is dissipated safely in a full pool, concentrating the oxidizer on a small volume of brake fluid leads to rapid consumption and violent reaction [4].
5. What the sources do not provide: no exhaustive dose–response or real‑world scaling data
Available reporting and abstracts show small‑scale lab parameters and document violent incidents, but they do not present systematic thresholds for when mixtures become explosive at larger scales, nor do they provide reproducible safety curves or ignition energies for different formulations of chlorine or brake fluids (available sources do not mention comprehensive scaling data or exact mass/volume limits beyond the cited lab demo) [1] [2].
6. Competing viewpoints and implicit agendas
Demonstration videos and hobbyist write‑ups sometimes present the effect as an entertaining stunt and show larger fireballs in DIY settings [5]; government and safety documents frame the same chemistry as a real public‑safety and criminal‑misuse risk [2] [3]. The entertainment pieces can implicitly underplay hazards; official abstracts emphasize repeated accidents and recommend strict controls. Readers should weigh the sensationalism of viral demos against the explicit safety warnings in government and technical reports [5] [2].
7. Bottom line and responsible guidance
The reaction is real, violent, and achievable with very small amounts (lab demos: ~2 g calcium hypochlorite + ~1 mL brake fluid) and can produce a brief fireball capable of shattering glass [1]. Do not attempt such experiments outside professional laboratory settings; sources unanimously frame the practice as hazardous and recommend expert supervision, fume hoods, and protective equipment [1] [2].