What are Best Ways to Test a Mylar Bivy's Insulation?

Testing Air Trapping Ability

To assess a Mylar bivy’s insulation, create a controlled environment by placing the bivy in a cold location or using a cold source, such as dry ice or a frozen gel pack. Next, use a thermometer to measure the temperature difference between the inside and outside of the bivy. If the Mylar bivy traps a significant amount of air between the fabric and the surrounding objects, you can expect to see a notable temperature difference, usually around 10-20 degrees Fahrenheit (5-10 degrees Celsius).

Observing Condensation and Moisture

Another method for testing a Mylar bivy’s insulation involves observing condensation and moisture buildup. Place a towel or cloth inside the bivy and leave it overnight in a cold environment. If the Mylar bivy is effective, you should see minimal condensation or moisture buildup. However, if water vapor is present, it may indicate that the bivy is not trapping enough air, and the insulation is compromised.

Measuring Heat Retention

For a more scientific approach, you can use a heat source, such as a candle or a heat gun, to simulate body heat. Place the heat source inside the bivy and measure the temperature difference between the inside and outside using a thermometer. A well-insulated Mylar bivy should retain heat for an extended period, potentially up to 30 minutes or more, depending on the surrounding conditions.