Surfactant?? I can answer that. It is a substance that decreases the surface tension of a liquid to promote more efficient drying. Same as some dishwasher detergents that contain one to eliminate/minimize spots on dishes.I worked at Kodak for many years and performed industrial radiography. To process the xray films we used a hand processing method (like a home photographer would in his darkroom) to process the films. The final step in the process (after rinsing) was a dunk into a tank of water that contained a very small amount of a surfactant. The films then went into a dryer
Being it was Kodak we used their own product called Photo Flo. I worked for other companies that also did manual processing of films and some used non Kodak film but they always used Photo Flo for the final rinse. It is a very high purity product and is available from photographic suppliers and even Amazon.
Ericsch mentioned mentioned he used 3 drops of surfactant in his brew. Photo Flo in our application was just one cap full of the product bottle to a five gallon tank. So, whatever volume is mixed up, very little is required. It will eliminate drying spots.
