Water temperature at 20 degree celsius

Discussion in 'Black and White' started by krishnakonan, Jul 20, 2016.

  1. I am going to do my first film processing at home. Ilford suggests 20 degree Celsius for Ilfosol. The instruction says that start with 23 degree and eventually it will come down to 20 degree because of heat loss. But when I checked water at 20 degree, it is absolutely cold. I was thinking that it would be warm at 20. My question is, is my thermometer correct? Is it really cold at 20 degree celsius? May be I am having this feeling because I am checking the water temperature for the first time in my life :) Please clear my doubt regarding this.
    As a side note, here in Dubai, there is no such thing called 'heat loss'. There is only 'heat gain' because the current temperature in Dubai is 43 degree celsius :( . So I have to start with 18 or 19 degree to reach 20 degree during development.
     
  2. I don't know if the discussion got anywhere but
    http://www.photo.net/black-and-white-photo-film-processing-forum/0099Zx
    There are a lot of Google™ hits out there under "tropical film development" and such like.
    I think the British Empire had to deal with tropical conditions in Asia and Africa. Perhaps they left some of that tradition behind, along with the breweries.
     
  3. If the ambient temperature is 43 degrees (plural), then of course 20 degrees will feel cold. You might check your thermometer against one known to be accurate. In central India in the 1960s we used to keep ice handy in summer.
     
  4. You should have several thermometers to check against each another. My primary unit is analog, tho I have several digital types (and those are relatively inexpensive). Hmmm, 20C deg is essentially room temperature (or 68F here) and you could control/stabilize your temp if you surround your dev. tank with water in a larger dish, tub, etc. Hopefully your interior doesn't get to 43C :>). It's easier to control things with plumbing where hot and cold water is on demand. Good luck.
    Les
     
  5. Most film developing formulas and methods suggest 20⁰C. I once research this and found that it was chosen because that was/is an average room temperature in Europe. That being said, the most important idea to express is, try to keep all the fluids at or near the same temperature. This is true because film contains multiple coats on the film base. Each coat will likely have a different coefficient of expansion. In other words, the emulsion swells when wet and likely all layers will not expand at the same rate. The swelling is necessary as it allows fluids to better infuse and percolate about. As the film dries, the emulsion shrinks back to almost its original thickness.

    Now developing time in solution is a variable. Temperature is key as is chemical strength. Most developer formulas come with time/temperature charts. No harm if the fluids are a few degrees above or below 20⁰C. Follow the time /temperature chart and try to keep all fluids nearly the same.

    I normally, for black & white films and papers, measure the temperature of the running water and work all fluids at that temperature. This is easy if you keep all the bottles and the film developing tank in a pan filled with running tap water. If this is impractical, place ice in the water tray and adjust all fluids to the same temperature.

    The 20⁰C for the fluids keeps the developing time within reason. The idea to keep all fluids the same temperature avoids reticulation. This is a condition whereby the emulsion appears as if it has shattered like a hit on automobile safety windscreen. Reticulation is caused by rapid changes in temperature as the film moves from solution to solution. Films that exhibit lots of grain can be traced to incipit reticulation, an early, not too noticeable stage of reticulation.
     
  6. Sorry about the missleading European figures. Over here tap water tends indeed to be colder than 20°C. During winter cheapskates might heat their rooms to maybe 18°C or less. I think comfort ends above 24°C. -Today was maybe the hottest of the entire year: Air 33°C, the local river 23°C and swimming in it would have felt like a good idea. Swimming in water below 18°C isn't recommended without extra precaution. - Most folks seem to be fine with temperatures in the 21-24°C range.
    I would settle for developing temperatures that my environment can easily provide. Heating isn't cheap, but cooling even way more expensive.
    What temperature is a bottle of whatever standing around in your shelf for days? - Is it complicated to have water at that temperature ready? - The danger I am aware of: one can mechanically ruin film by rinsing it in water much colder than the previously used chemicals.
     
  7. Hello everyone. Once again I will put forward my "system" to control developing temperatures. Simple and relatively cheap. Get an Igloo (or other brand) hard shell cooler. Recycle some 970ml and 650ml drink bottles. The cooler pictured has chemicals and water to develop & wash (2) 135-36 or (1) 120 film in a 450 ml Nikor SS tank. Add cold/hot water as needed. Usually "stability" is reached in 30-45 minutes. Enjoy, Bill
    00e3hP-564424784.JPG
     
  8. In the winter, my basement darkroom gets down to about 15C. In the summer, it might get to 25C. Incoming water, from underground pipes, is always cold. I fill up bottles with water, to allow it to adapt to room temperature.
    In Dubai, you might find color development easier. C41 is about 38C. In cool countries we need a warm water bath and heater to keep the chemistry warm enough. It will be natural for you.
    You could use XP2, which is a black and white C41 film, or just about any of the color negative films. The hardest part for us is keeping the temperature right!
    For at least 50 years, normal black and white films had development temperatures specified from 19C to 24C.
    I am not sure how warm you can go with current black and white films before the emulsion becomes too soft. Diafine specifies up to about 30C. Diafine is convenient as you don't have to time carefully. Otherwise, the times will be too short at the higher temperatures.
    Earlier films, maybe 80 or 90 years ago, used cooler temperatures, as the gelatin would melt. Maybe 10C or so. But don't worry about those.
     
  9. Google up calibrating a thermometer. Basically make a water and ice slushy and after a few minutes put your thermometer in so that it is not touching the side of the container. It should read 30 degrees Fahrenheit. Anyway google it up to get the technique down. Some thermometers can be calibrated. In general cooking thermometers are probably not accurate.
    Myself I use a Paterson photographic thermometer from BHP. About $25.00.
     
  10. Yes, in normal summer weather it will feel cold. 20degrees is the correct "recommended" temperature and its good if you can have all you liquids at the same temperature. That includes developer, fixer and stop bath.
     
  11. Also, 20C is 68F. Integer multiples of 5C have integer values in F, so it is at least slightly more convenient for us in countries using F.
    C41 and E6 are warmer, close to 38C, not because it is convenient for users, but because it is faster. The films are hardened to survive the higher temperature.
     
  12. Part of my adventure back into film was the challenge of temperature control in developing. In summer here it can hit 45C regularly and in winter, now its between 12-23C. My partner, who will shoot film to the grave bought a used Jobo system for $200. This has temperature control. It made a massive improvement to her workflow. Just a suggestion.
     
  13. Thanks to everyone for reply.
    Now here in Dubai, the tap water is coming at 43/44 deg. celsius. You can't wash your hands or utensils for too long without harming your hands. We have to draw water from the taps and store in the night for 12 hours for taking bath in the next day morning. When I checked the stored water in the tub in the morning it was around 28C deg.
    Water is gaining heat at 1 deg C per 5 minutes, when I checked yesterday. I set the water at 19C and after 5 minutes it was 20C.
     
  14. Bill has a great system for keeping solutions at the desired temperature. Usually I don't have a problem (darkroom has a vent from the HVAC system) but on the occasion where my solution is too warm or cold I take a test tube (Kimex or Pyrex) and fill it with either ice water or hot water (depending on whether I want to cool the solution or warm it) and use it to stir the solution for a few minutes until I reach the desired temperature.
     
  15. The background, as you all know, is that at higher temperatures lots of chemical reactions are faster.
    There's nothing obviously wrong in developing in higher temperature and compensating by shortening the timing. However, at some point, development times become so short that there's really no way to control what's happening. High temperatures also affect things like the emulsion, etc.
    43 degrees is really pretty hot for water out of the tap. I've not noticed it in Africa, but I wasn't trying to develop film either.
     
  16. James G. Dainis

    James G. Dainis Moderator

    I hope that 43°C is not room temperature where you will be working. A lot has been said about getting the developing liquids to the right temperature, around 20°C. You also calculate that the developer will rise about two degrees while developing due to the high room air temperature around the tank. But if you have 500ml of developer at 20°C and pour that into a tank with the reels and film weighing about 250mg at a temperature of 43°C, the developer will rise to about 28°C as the tank also cools to about 28°C. <P>

    I would suggest after loading the film into the tank you put it into a cooler to get the temperature of the tank, film and reels down to 20°C. You could also pre-wet with 20°C water to cool things down before using the developer. I would be careful with that as there is such a difference in temperature (43°C - 20°C) There is this thing known as reticulation. Usually that happens during the developing process itself. If there is a large difference between the developing chemicals the emulsion can crack or distort. I don't know if that would happen if you poured 20°C water onto 43°C film.
     
  17. But if you have 500ml of developer at 20°C and pour that into a tank with the reels and film weighing about 250mg at a temperature of 43°C, the developer will rise to about 28°C as the tank also cools to about 28°C.​

    I haven't weighed my tank lately, but I presume it is closer to 250g than 250mg.

    The heat capacity of tank and film are about 0.1 (cal/g), compared to 1.0 for water and water solutions. 20C solution and 43C tank will result in about 21C together. Plastic tanks will weigh less, and end up even closer to 20C.
     
  18. James G. Dainis

    James G. Dainis Moderator

    I forgot to take it into account but specific heat of plastic is about 0.4 compared to that of water at 1.0 that is it only takes 0.4 Btu to raise one pound of plastic one degree F (or 0.4 kcal to raise one kg of plastic one degree C.). I'm used to dealing in BTU and degrees F. I was running estimates through my head (foolishly forgetting the specific heat). I may do some more accurate calculations later but I would guess that there should be about a two to three degree rise in temperature when 20 degree developer is put into and cools a 43 degree tank, reel and film. <P>

    From actual practice I ruined some film before I found out that six sheet films at room temperature dropped the developer from 101&deg;F to 98 &deg;F. even when using a water bath. I learned to raise the developer by 1/2 degree for each film that I was going to use.
     
  19. Thanks everyone for the response!
    My room temperature is around 28/27 celsius.
    I will rehearse the process of controlling the temperature before doing the actual film processing.
     
  20. Seems that ABS, a likely plastic for plastic tanks is 0.34cal/g, I didn't know it was that high.
    But stainless steel is closer to 0.1, maybe 0.12 cal/g.
    I suspect more use SS than ABS for color, but maybe not.
    But the OP should have an easy time with C41, though a little work to get it down to 38C.
     

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