There are three ways to wet gate motion picture film -- two of them that can be used by still photography-- the "aquarium" model (as above), where the film is totally immersed in a fluid bath within an aquarium or tray of glass (and yes, bubbles ARE Hell in motion picture work too) and the applicated method whereby a wick with the fluid is passed over the element and placed directly in the printing aperture and exposed.

The Edwal "No-Scratch" was probably silicone oil and was applicated to a negative and placed in an enlarger immediately. Trick was to get just enough; too little and it didn't do the job and too much and it runs down into the enlarger...

Better have some good film cleaner, 1:1:1 or 1:1:2 Trichlorethene, or similar to remove it though; it can be hard to get off both the neg and the carrier.