Redscale - Variable results.

 Redscale is an experimental technique and therefore the results are highly dependent on the following

• Film Stock
• Expiry date of film
• ISO that the film is shot at

Looking at the ISO, assuming fresh, in date, film there are several exposure methods

• Underexposure
• Correct exposure
• Overexposure

Redscale film is a method of reversing the film so that the back of the film and red emulsion layer are exposed before the green and blue.  Because the film is exposed the "wrong way around" you need to compensate and allow extra light.

Redscale - Wikipedia

This is where the concepts of over, correct and underexposure can be brought into play.

As an example, suppose the film stock is normally rated at ISO 400, exposing at ISO 400 would give a hugely underexposed negative. 

• Underexposure - 1 stop extra light (ISO 200)
• The resulting photograph should be Dark Red
• Correct exposure - 2 stops extra light (ISO 100)
• The resulting photograph should be Orange
• Overexposure - 3 stops extra light (ISO 50)
• The resulting photograph should be Yellow

Much of this will depend on your camera and it's ability to change ISO from frame to frame.

The experimental nature of this technique means that you shouldn't be too precious until you have dialled in a filmstock with a camera, i.e. you've experimented.

Note the predominantly orange tones.

Note the overall yellow tones.

As a post script to this, I have made a roll of Harman Phoenix colour film into a roll of redscale. Harman do this themselves and sell it as Harman Red 125.

Harman Red 125

They suggest an ISO of 125, which is two thirds of a stop for best (their suggested) results.

My camera, the Lomo LC-A just has ISO 50, ISO 100, ISO 200, ISO 400, so I'll set ISO 100 but I can try 200 and 50 as well. Thats the beauty of experimental techniques, you can experiment!