I don't know when the spiral for film development was invented, but it wasn't for sure the first device imagined for that. Here we have one of its ancestors. The drawing below shows how to do it in a simple tray and above a picture with an improvement that ensures that the film will be always going into the bath. The operator must keep swinging all the time.



That was back to the end of the XIX century. As KODAK launched the   Film Tank;   in the early 1900's probably the idea of developing the film in a loose roll (spiral) was rapidly spread. The only difference between the KODAK film tank and spirals we use today (maybe it is already yesterday too) is the fact that KODAK's is a light tight spiral and so much more complicated. That was in order to allow day load operation. But at the end, it is not that hard to load an spiral in complete darkness and drop it into a tank so it evolved to the simplest and also the best way.




I took the opportunity to feature too AGFA vintage spools in wood and metal. Those are for 120 film, maybe the most popular format after the 135. It was created also by KODAK to feature its   Brownie Nš2;