How to Make Redscale Film

Materials needed:

scissors
masking tape
2 Rolls of ISO 400 color negative film.
changing bag
lightproof container

1. Place the scissors, 1 roll of film, and lightproof container in the changing bag and zip it closed. 
2. Reach through the armholes, and carefully pull the film all the way out of the film catridge, allowing it to coil naturally. 
3. Using the cartridge opening as guide, cut the film as straight as possible about a half inch from the opening. 
4. Place the film in the lightproof container and pull your arms out. 
5. Open the changing bag, and remove the scissors and empty film cartridge. 
6. Take the second film cartridge, and trim the leader off with a straight cut across the entire width of the fim. 
7. Join the end of the film from the full cartridge with the remaining half inch of film from the empty one so that the emulsion faces in the opposite direction. 
8. Wind the film into empty container just enough so that the joint is inside. 
9. Place the joined cartridges into the changing bag along along with the scissors and masking tape, and seal it. 
10. Wind the film from the full cartridge to te empty one.
11. When all the fim has been transferred,  cut it as straight as possible about a half inch from the cartridge opening.
12. Put the newly filled cartridge aside. 
13. Remove the coiled film from the lightproof container, and join the cut end to the now empty cartridge using a strip of masking tape. Be sure the emulsions face in the opposite direction.   
14. Wind the film back into the cartrdge, leaving only the leader exposed. 
15. Remove everything from the changing bag. 
16. Trim the leader off the second roll with a straight cut across the entire width of the film.

The technique above works for making rolls in pairs. If you have reusable 35mm cartridges, you can make them faster one at a time.

1. Cut the leader off the film
2. Attach it directly to the inverted spool of the reusable cartridge
3. Reassemble the reusable cartridge and place both in the changing bag
4. Transfer the film from the full cartridge to the empty reusable one, cutting the film within a half inch of the donor cartridge. 

You now have an empty cartridge to start the next roll!

Because the light is traveling backwards through the film, it loses about one to one and a half stops of sensitivity, so rate it accordingly. For example, for ISO 400 film set your camera for 100 to 200, but process it the way you normally would.