Hair bleach, a mixture of lightener powder and liquid developer, is not traditionally flammable like gasoline or wood. A substance is flammable if it easily ignites and sustains a fire, a characteristic hair bleach lacks. However, its ingredients are powerful oxidizing agents that generate oxygen, rapidly accelerating combustion if they contact incompatible materials or are improperly mixed. While the product will not spontaneously ignite, misuse can lead to violent chemical reactions involving extreme heat, pressure, and fire.
Oxidizing Agents in Hair Bleach
The hazard potential of hair bleach is rooted in the powerful oxidizing capabilities of its separate ingredients. An oxidizing agent readily releases oxygen in a chemical reaction, acting as a catalyst for the combustion of other materials. The agent itself is not the fuel, but it provides the necessary oxygen for a fire to start or intensify.
The liquid developer is an aqueous solution of hydrogen peroxide (\(\text{H}_2\text{O}_2\)), a potent oxidizing agent. When mixed with the powder, the hydrogen peroxide provides the oxygen needed to break down the hair’s natural pigment, melanin. The powder lightener contains persulfate salts, such as ammonium persulfate or potassium persulfate, often in high concentrations (25 to 60 percent).
Persulfates significantly boost the bleaching action of the hydrogen peroxide. These solid chemicals are a hazard when stored improperly, as heat, moisture, or organic materials can trigger their decomposition. The combination of hydrogen peroxide and persulfates creates a highly reactive chemical system that can violently decompose if mishandled or contaminated.
Understanding Exothermic Reactions
The danger of mixed hair bleach relates to the highly energetic exothermic reaction, a chemical process that releases heat. When the developer and lightener powder are combined, the oxidation process releases significant thermal energy. This heat release speeds up the reaction, allowing the bleaching to occur quickly.
The problem occurs when this heat cannot dissipate, such as when the mixed product is placed in a sealed container or under an occlusive covering. Trapping the heat accelerates the reaction rate, causing a runaway process called thermal runaway. This rapid acceleration leads to a swift buildup of internal pressure and a massive surge in temperature. The result can be the forceful rupturing of the container, the release of toxic fumes, or spontaneous combustion.
Introducing foreign substances, especially metals, can violently accelerate this exothermic process. Metal ions, even trace amounts from a metal bowl or clip, act as catalysts. These catalysts lower the activation energy of the peroxide decomposition, causing the reaction to become dramatically faster and hotter. This contamination can lead to an almost instantaneous violent chemical decomposition, creating intense heat and fuming.
Safe Handling and Storage Practices
Handling
The chemical properties of hair bleach necessitate strict safety protocols to mitigate the risk of hazardous reactions. Always prepare and use the product in a well-ventilated space to prevent the buildup of fumes or gasses. When mixing the developer and powder, use only non-metallic tools and containers. Contact with metal can trigger the violent catalytic decomposition of the hydrogen peroxide.
Strictly follow the manufacturer’s mixing ratios, as altering proportions can increase the heat generated. Never attempt to store mixed hair bleach, even briefly, because the ongoing exothermic reaction generates gas and pressure that can cause a sealed container to burst. Promptly dispose of any unused mixed product by thoroughly diluting it with a large volume of water before pouring it down the drain.
Storage
For storage, separate the lightener powder and the liquid developer, keeping them in their original, tightly sealed containers. Both components must be stored in a cool, dry area away from direct sunlight, heat sources, and incompatible materials. Incompatible materials include organic substances, reducing agents, acids, and metal contamination. The lightener powder must be kept away from moisture, as water can initiate decomposition and pressure buildup.