What is an appropriate method to collect a dry stain?

Using distilled water is an appropriate method to collect a dry stain because it helps to minimize potential contamination and preserves the integrity of the sample. Distilled water is free from impurities and chemicals that might interfere with subsequent testing or analysis of the stain. It can effectively dissolve or suspend soluble materials, allowing for the safe collection of the stain without introducing foreign substances.

Using alcohol, while sometimes effective for certain types of substances, may alter the composition of the stain or cause degradation. Saline solution, which contains salt, might not dissolve all types of stains adequately or may introduce contaminants. A wet cloth can spread the stain or mix it with other substances, leading to a less reliable sample. For these reasons, distilled water is generally considered the best choice for collecting dry stains.