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Processing

Metal vs. Plastic Reels
Using a color head for variable contrast filtration
Black & White Film Developing

Metal vs. Plastic Reels

Stainless steel reels (and tanks) transfer heat more rapidly than plastic. That's another way of saying they will warm up or cool down faster than plastic reels (or tanks). For film processing, temperature stability is a better characteristic than fast temperature changes. So while plastic tanks and reels take longer to get to the "proper" temperature for processing, they also stay there more reliably than stainless steel.

Stainless steel is NOT impervious to many photographic chemicals. Specifically bleach and bleach/fix used in most color processes will eat through 316 stainless steel. Granted it won't happen overnight, but most commercial processors today are made with PVC plastic tanks rather than stainless steel for this very reason.

Most stainless steel reels, if dropped, generally become useless. Once the metal spirals become bent, it is virtually impossible to bend them back to their original position. Plastic reels, if made with the right materials, will withstand the impact of dropping (not throwing) and the spirals will "bounce" back to their original position. The result is they are less likely to be damaged by dropping, but they will still bend when our plastic would spring back.)

Loading either reel type becomes the source of many debates. It is generally conceded that loading stainless steel reels is somewhat more difficult to master, especially for 120 film. But once mastered it is generally possible to load a stainless steel reel in about half the time of a plastic "walk-in" reel. Also since stainless steel reels are loaded from a clip or teeth in the center of the reel, and then wound around the center, rather than sliding along the spirals as in plastic reels, they are less likely to be affected by humidity than plastic "walk-in" reels.

Stainless steel reels cost substantially more than plastic reels. You can generally count on double or triple the price of plastic, when purchasing a quality stainless steel reel.

However, the actual processing characteristic differences are probably the most important factor to consider. There are virtually none. That's right! Both plastic and stainless steel reels will result in high quality film processing. Neither one has a distinct qualitative advantage. 

Using a color head for variable contrast filtration

In addition to printing color photos, one of the great advantages of a dichroic color head enlarger is the ability to dial in black and white variable contrast filtration, rather than place filters below the enlarging lens. Filters under the lens will reduce the effective sharpness of your image. 

Simplistically, you could start with the assumption that white light is approximately a contrast grade of 2.5 and know that by dialing increasing amounts of magenta filtration you increase the contrast of your print. Conversely, dialing increasing amounts of yellow filtration would result in a lower contrast print. 

However, while you are dialing in either filtration, you are changing the effective speed of the paper, due primarily to the filter factor which reduces the amount of light reaching the paper. To overcome the filter factors, enlarger manufacturers suggest that you dial in certain amounts of the "opposite" filter to maintain a relatively consistent light output. This is exactly how Variable Contrast (VC) heads work. 

VC heads are principally just color heads with different cams to control the filters. As you increase the contrast filtration, the magenta increases and the yellow reduces, but the exposure remains constant. However, with VC heads you cannot print color images, since you do not have separate control over the individual filters, which is essential for color printing.

Black & White Film Developing 

1. You need: film developing tank, thermometer, at least one accurate measuring cylinder, film developer, film fixer, two empty bottles, scissors, two clothes pins.

2. Optional items include stop bath, photo flo and accurate timer (you can manage with a watch or clock with second hand.) You also need a totally dark space to load the film into the tank.

3. In total darkness, load the film onto the reel, put this inside the tank body together with the centre column, and screw the lid on. Now take it into normal room lighting.

4. Make up the developer and fixer (usually 300ml per film) to the manufacturer's instructions. For convenience, choose a liquid developer which is diluted for one shot use. Instructions for saving and reusing solutions are included with your chemistry.

5. Stand the bottles containing these solutions in hot or iced water to raise or lower the temperature to that stated in the developer instructions (normally 68F.) 

6. Pour the developer into the tank, and start timing. Tap the tank solidly to dislodge any air bubbles from the film surface. Agitation is normally by using a waterproof lid and turning the tank upside down, pausing briefly and turning it back. Agitate just enough that the developer is washed evenly across the film surface. Excessive agitation increases graininess of the the film.

7. Follow the developer instructions for time and agitation and at the end of the time pour the developer down the sink (or back into the bottle if it is to be reused.)

8. Pour in water at process temperature. Agitate a couple of times, then pour out and fill with more water, 3 or 4 times. (Stopbath, agititate for 1 minute, return to bottle.)

9. Pour in fixer. Agitate frequently for 4 minutes (rapid fixer) or 8 minutes (sodium thiosulphite fixer.) For T-Max films increase times by half. Return fixer to bottle.

10. Wash in water roughly at process temperature. Either use changes of water at roughly 2 minute intervals for 20-30 minutes, or a slow stream of running water. Failure to throughly remove the fixer with a through wash will shorten the life of the film.

11. Give a final rinse - 1 minute - in a dilute solution of a photographic wetting agent like photo flo.

12. Pull the film carefully from the reel and drag it between 2 fingers to remove the excess water. 

13. Then hang the film to dry. 

Tips: 

1. Before loading, trim the end of the film sticking out of the casette square, then make a small cut across each corner to round it.

2. Fixer can normally process at least 20 films per litre of solution. Put a label on the bottle and make a mark for each film you process. 
 
 

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