How Much Developer?

<p>Hi, just setting up my own darkroom and I wanted to know how much developer at stock solution (in ml/l) i need to develop one roll of 35mm or one roll of 120? I'm going to be using a Patterson multi-reel 3.<br>

Also, do my chemicals have to be at 20c?</p>

<p>Thanks</p>

<p>Did you check the bottom of the tanks? Most of them have the amounts printed on the bottom.</p>

<p>Paterson tanks typically need about 300 ml. of solution for each 35mm reel, and about 600 ml. for each 120 roll. And yes, the amounts are embossed into the bottom of the tank.<br>

Your chemistry does not haver to be at 20C, but processing times are given for that temperature. Lower or higher temperatures will require different processing times.</p>

<p>There are corrections of developing times for different temperatures. But the most consistent results will be gained by processing at 20°C. Consistency is something you really want to have in your B&W processing. You may eventually decide that you want to develop a little longer or shorter than the printed times, but you won't be able to determine or control this unless your processing is very repeatable.<br>

There's two ways to get the developer to 20°C. The right way is to put the container holding the developer into a water bath at 20°C, or have two water baths (hot and cold), and dip the container into each and stir until your thermometer reads 20°C. This works best with a stainless steel container, since it has such good thermal conductivity.<br>

The more "cheaty" way, if you're diluting developer, or making it from a concentrate like DD-X, HC-110, or Rodinal, is to mix hot and cold water together to hit the desired temperature. But using hot water to dilute developer really isn't ideal, since it has a lot of little air bubbles in it, so you'll oxidize the developer a bit reducing its activity.<br>

Also, note that some developers at some dilutions, may call for more working solution than is required to cover the film. For instance, D-76 1:1 dilution calls for 16 ounces (about 500 ml) of the diluted developer per 35mm 36-exposure roll. This is to prevent developer exhaustion.</p>

<p>Twenty degrees' Celsius is considered standard because it is the average room temperature thus making it easy to get all the various chemical baths and wash water equal.</p>

<p>Since running water is as much a part of the processing steps as the chemicals, you should measure the cold-water temperature. If below twenty Celsius, see if you can adjust up by playing with the hot-cold via the mixing faucet.</p>

<p>If it is impossible to achieve twenty Celsius then it is likely best to place the bottled chemical in a water bath, bringing them to equilibrium with the cold water temperature.</p>

<p>Stated another way, rather than risk working with a wide temperature spread, best process using the cold water temperature. Film has a multi layered structure; each has a different coefficient of contrition and expansion. If the various fluids of the process are vastly different, reticulation can occur. At worst, the film will resemble shattered glass. At best, reticulation looks like increased grain. Try to keep all fluids within three degrees Celsius of each other, adjusting immersion time based on product instructions and tables. </p>

<blockquote>

<p>But the most consistent results will be gained by processing at 20°C.</p>

 

</blockquote>

<p>That's not true. I run my process at 75F all the time and my results are consistent. The key is to run the process the same way every time. Of course, I adjust the development time down to compensate for the increased temperature.</p>

<p>The manufacturer's of developers all have a recomended temperature time for development, usually 68 deg F, 20deg C. There is a reason for the recommended temperature: it is the temperature that works the best for that developer. Film has similar recommendations for the same reason. Most developers have 2 active developers as components. Typically, Metol and Hydroquinone. These 2 components do not behave the same way in relation to eachother at different temperatures.</p>

<p>If there is nothing printed on the bottom of the tank then set your reel in the bottom of the tank and add water til it covers the spool about 1/4 inch or 6mm or so. Measure this amount and round up to the nearest round number like 300 or 325 or what ever. If you have two reels then install both reels and repeat. I have a few tanks that don't have anything on them for volumes.</p>

<p>You may get inconsistent development if you develop for less than 5 minutes. At 68ºf the time is longer than at 75ºf. If you are using a really active developer then you may want to cool your chemistry down even further to lengthen the time. I don't think I would go below 58ºf except for special conditions.</p>

<p>What developer and film are you using? Not that it matters much, just curious.</p>

<p>Sam - over the years I have had to answer the same two questions and dozens more in working out my darkroom work flow. But with all the information available on the internet just who do you believe? Some of my questions were answered in my own darkroom through trial and error. When the late Fred Picker received questions he would often stamp and return letters marked "TRY IT!" and, truthfully, that may be the best way to learn. Your two questions could be resolved with the "TRY IT" method but only with considerable expenditure of time and materials. So what to do? With certain technical questions I have come to rely on a small group of folks I trust so completely that try it and see seems unnecessary. One source is the late Dr. Richard J. Henry author of Controls in B&W Photography. A second are two retired Kodak photo scientists Dick Dickerson and Silvia Zawadzki who are still writing for Photo Technique magazine. They, in fact, have written specifically touching on both of your questions. They wrote an entire article on your temperature question (PT-July/August 2005). To para phrase - the particular temperature you choose is functionally irrelevant - but keeping that temperature constant is very important. I had to correspond with them to answer your stock solution volume question. Answer - use at least 100ml of developer in the most concentrated form for which the manufacturer lists a recommended time and temperature. For example, that would mean 100ml of stock D76. If you insist on using the minimum I suspect your times would be considearably longer then Kodak recommends. So who do you trust. Best - resolve the question in your own darkroom. If that is not practical find a trusted source. I my case that would be Richard, Dick or Silvia among others.</p>

<p>You have been given some sage advice in this thread, Sam. Having commercially developed many thousands of rolls of colour and black and white film over the years, there are two principals that have never failed me, 'consistency' and 'read the directions'. Photographic companies don't spend tens of thousands of dollars each year on R&D for no reason at all. They do it so that you, the consumer, will have the best possible outcome while using their products. Develop too hot and you may run into reticulation due to a swollen emulsion. Develop too cold and the emulsion stays too hard, increasing the time required for penetration of the developer and also increasing the time of the chemical process itself. </p>

<p>Sage is a spice. To have a Sage in your village is the Spice that keeps the young growing. :-)</p>

<p>Truer words were never spoken, Larry!</p>