Hand sanitizer has become a common product for maintaining hygiene, particularly when traditional soap and water are not readily available. Many wonder if this product, a common item carried in bags and cars, can freeze in cold conditions. Its composition explains its behavior in cold conditions.
The Role of Alcohol in Freezing
Hand sanitizer resists freezing due to its high alcohol content. They contain ethanol or isopropanol as active ingredients, usually at 60% to 95% by volume. Alcohol significantly lowers the freezing point of water, known as freezing point depression. This means a mixture of alcohol and water will freeze at a much lower temperature than pure water, which freezes at 32°F (0°C).
For example, an ethanol solution at 60% concentration freezes around -35°F (-37°C), while a 70% ethanol solution freezes at approximately -55°F (-48°C). Similarly, a 70% isopropanol solution has a freezing point of about -79°F (-61.7°C). These low freezing points mean most hand sanitizers withstand typical winter temperatures without solidifying. If hand sanitizer freezes under normal cold conditions, it may indicate lower alcohol content, potentially affecting its germ-killing ability.
What Happens When Hand Sanitizer Gets Cold
While hand sanitizer resists freezing, extreme cold can affect its consistency. It might become thicker, develop a slushy texture, or even appear to freeze solid, though this typically requires temperatures well below what most people experience, often in the range of -35°F to -50°F (-37°C to -45°C). This texture change does not harm the alcohol.
The primary concern with chilled or frozen hand sanitizer is usability. A thickened or slushy product can be difficult to dispense from its container, and if it thaws, it might not spread evenly on the hands. Uneven application could reduce its ability to cover skin and sanitize. Once it warms to room temperature, its efficacy is restored, assuming the alcohol has not evaporated due to improper storage.
Keeping Your Hand Sanitizer Effective in Winter
Proper storage maintains hand sanitizer effectiveness in cold weather. Keep hand sanitizer indoors, away from extreme cold. Avoid leaving bottles in unheated places like cars overnight, as prolonged exposure to low temperatures can change consistency.
If hand sanitizer becomes very cold or appears frozen, allow it to return to room temperature before use. This ensures the product dispenses smoothly and can be rubbed across all hand surfaces. Regardless of temperature, always apply enough product to cover your hands completely and rub them together until dry, ensuring the alcohol has sufficient contact time to sanitize.