Back in the film days, there was technique of exposing a negative, while it was being developed, which distorted the image, sometime very strikingly. This manipulation had a name, which I cannot remember.
You're be looking for the Sabatier Effect.
The technique can be used on film or when printing but is more commonly used when printing as the effects can be better controlled in the darkroom.
It is frequently confused with Solarization which occurs from a gross overexposure. The effects can look similar.