This chemical mixture of Fluorescein causes a catalytic reaction to occur between the hemoglobin in blood and oxygen. This reaction produces a luminescent stain which will luminesce in the dark when excited with UV or ALS. The major advantage of Fluorescein is that it will continue to luminesce for hours under UV or ALS after the initial application, and without additional applications of the reagent. This product is commonly used to detect blood spatter, blood stained fingerprints, and footwear impressions, as well as, blood evidence which has been concealed or cleaned. Fluorescein also reacts with materials other than blood, therefore, caution should be exercised when interpreting luminescent areas. Provided as an 8 oz. premix set.