Processing
Tube Long processing times are the most boring aspect of darkroom work. Standing over a sink and agitating film for long plus-developments irritates me to such an extent that I finally got a machine to do it. Now, while the thing is running for 15 or 20 minutes or so, I can be off doing something less boring. It also prevents developer "surge" which is often evident in large, unrelieved areas of sky or snow. As you can tell from Fig 1, the tube is submerged in a temperature controlled water bath during development. Fig.2 shows the lining pulled out. This material is a project grid available from stores like Hobby Lobby. It provides a smooth surface for the back of the film to rest against while allowing chemicals to circulate evenly behind the film. The tube itself is made from standard PVC drainpipe and fittings. The bottom is flat, enabling it to stand upright while loading. In this position, it can be filled with water, eliminating the need to dry it out between runs. Pipe of this sort is white and translucent, hence the black ABS glue covering inside and out. The light trap in Fig. 3 is a ¼" section of ABS with two deep grooves cut in the circumference on a lathe. Alternating sections were then cut out as shown. It is completely light tight and requires no stopper. Developer is introduced while running and streaks are eliminated. Power is provided by a 60-rpm reduction motor, available from Grainger, and two large ¼" O-rings from McMaster Carr.
|
1 |  |
| 2 |  |
|
| 3 |  |
|