Hot Plates for water bath?

Discussion in 'Darkroom Equipment' started by markbarendt, Apr 3, 2010.

  1. markbarendt

    markbarendt Subscriber

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    Anybody tried using a hot plate as a heat source for keeping color chemicals at the right temperature?

    I'm using small tanks for film and trays for prints.

    I've looked at some circulating water heaters and water baths used in science labs but they are either real expensive or too small or somehow don't inspire any confidence in me that they could keep up.

    Right now I'm using an old electric hot pad and a modified fish tank heater to keep my water bath warm but I have a tough time keeping the chemicals at 100 degrees for C-41, tends to float down into the low 90's, I end up microwaving the developer for every run.

    I'm using the low-temp two-step RA-4 chemical kit from Ultrafine right now, but I'm getting more serious about RA-4 and looking at buying chemical kits that will need to maintain 95 degrees across three trays (Developer, Blix, & Stabilizer) and this is going to mean a lot more surface area to keep warm.

    I was thinking that an electric hot plate or two and large (non-disposable) turkey pans might make a cheap, adjustable, and workable water bath system.

    This http://www.cooking.com/products/shprodde.asp?SKU=255589&mybuyscid=5388418602 also looks interesting but even the low setting is 130-150 degrees.

    Any experiences or other ideas welcome.
     
  2. Rick A

    Rick A Subscriber

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    I think it would work IF you have control of the temperture. Going by the "L,M,H" settings alone might not be viable unless you can monitor the actual temps.
     
  3. markbarendt

    markbarendt Subscriber

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    I have thermometers for each tray/chemical.
     
  4. Rick A

    Rick A Subscriber

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    Thats good for monitoring the temps, but what about establishing the temp you need, and maintaining it IF the settings provided by the hotplate arent the ones you need? Could you find one that has a thermostat that reads in degrees, I believe that woud be ideal.
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    Mark;

    Have you ever considered running RA4 at room temp? Kodak's RA-RT Developer Replenisher works from 68 F to 100 F. No heating or cooling needed. Just adjust the color balance and time for your darkroom temp.

    PE
     
  6. markbarendt

    markbarendt Subscriber

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    No, I did not know that.

    So if I get

    This developer http://www.adorama.com/KKRADRRT.html

    This Bleach/Fix http://www.adorama.com/KKRABFR10L.html

    And

    This Stabilizer http://www.adorama.com/KKRASR10L.html

    I should be ready to go at room temp.
     
  7. Photo Engineer

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    You do not need the stabilizer for color paper.

    PE
     
  8. markbarendt

    markbarendt Subscriber

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    While we're on the chemical topic...

    For C-41 I've used the Trebla kit but it's about gone and I was hunting at Adorama for all the chems. I came up with the following list:

    Developer http://www.adorama.com/KKFCDR5G.html

    Developer Starter http://www.adorama.com/KKFCDS.html

    Bleach Part "A" http://www.adorama.com/KKFCBRA125G.html

    Bleach Starter http://www.adorama.com/KKFCBSG.html

    Fix http://www.adorama.com/KKFCFR5G.html

    Stabalizer http://www.adorama.com/KKFCSRG.html

    My confusion here is that the Trebla kit had a one part bleach/replenisher, just add water.

    Adorama shows part "A" but no "B" at least on the web, the only other bleach thing they show is the Bleach Starter.

    Is this the full list or what?
     
    Last edited by a moderator: Apr 3, 2010
  9. markbarendt

    markbarendt Subscriber

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    Cool, thanks.
     
  10. markbarendt

    markbarendt Subscriber

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    Have not found one with a thermostat, I agree that that would be great.
     
  11. Photo Engineer

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    There was a post several years ago here that described small animal heating pads that could be set to a desired temperature. The example shown was for baby piglets. It might be of interest here.

    I prefer to do things at room temp.

    Regarding C-41, current Bleach III consists of 2 parts. Versions from 3 or 4 years ago used 1 part. Replenisher for bleach, fix and stabilizer are not needed.

    PE
     
  12. markbarendt

    markbarendt Subscriber

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    Thanks PE

    Mark
     
  13. Hexavalent

    Hexavalent Subscriber

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    My experience with electric hot-plates, 'food warmers' etc., is that the thermostatic controls are less than satisifactory - large temperature swings, and quite often 'load dependant' (meaning sensitive to the amount of water etc., being kept warm). If you are a DIY'er, one can cobble together a temperature controller from a triac and temp-sensor (lm35).
     
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  15. Photo Engineer

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    I use a Corning 5x7" ceramic hot plate/stirrer with integral control probe. I set the temperature that I want and it stays there +/- 1 degree or less. I do use it to keep my C41 stuff up to temp without wasting water.

    PE
     
  16. markbarendt

    markbarendt Subscriber

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    Those are nice! Little pricey though.
     
  17. Photo Engineer

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    Yes, but essential for making emulsions.

    And, that was your question in the OP..... So, I pointed out that it was possible.

    PE
     
  18. dwross

    dwross Subscriber

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    Nonsense.
     
  19. Photo Engineer

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    It is pretty hard to get things to 50 - 80 C using hot water. It takes a lot of hot water. If you heat it, you use a hot plate to keep the bath up there.

    I have tried a lot of alternatives for making emulsions well and the controlled hot plate does well.

    An uncontrolled plate is very nice, as long as you are willing to stand there and fiddle with the knob. That works just fine and is less expensive but more labor intensive.

    So, in the absence of any alternative, I feel that I can stand by what I say.

    PE
     
  20. markbarendt

    markbarendt Subscriber

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    Yes it was and I do appreciate the info, I did not know those existed.

    I'm not making emulsions yet and the water bath/microwave system is giving me good results so I may join the "fiddle the knob" crowd for now so I can put more money into film, paper, and chemicals. :smile:
     
  21. tiberiustibz

    tiberiustibz Member

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    The problem with those plates would be the residual heat kept up in the plate. If you turn it on 10 and then shut it off when the bath reaches temperature, the bath temperature will continue to rise for some time after.
     
  22. Photo Engineer

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    That is why the ones without the controller require constant attention. With the controller, this does not happen.

    OTOH, if you use a large water bath on the hotplate, the overshoot is minimized due to the inertia of the water and a glass container (pyrex) minimizes this to an even greater extent. Use of Stainless or other metal containers tends to maximize losses and cause bigger over and under shoot.

    PE
     
  23. markbarendt

    markbarendt Subscriber

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    The idea of using a large bath for it's inertia and buffering the heat transmission with glass fits nicely into what I am trying to accomplish; reasonable manual control.

    One of my concerns is the physical size of what I want to keep hot, specifically I would like to be able to keep "all the chemicals" at the same temp. For C-41 that means 4 one-liter measuring jugs and a developing tank or two. For RA-4 that may mean a 16x20 tray.

    Yes I do now understand that room temp works fine for RA-4 but my darkroom temp can vary from say 60f in winter to 85f or so in summer. I really need to have some heat source in winter anyway so standardizing at about 92 as recommended in tech pub J39 seems prudent. That also shortens the time in the tray which is also preferable.

    I did find an infinitely adjustable hot plate that may work. Given it's limited diameter I can see that I would need to build a support of some type to keep a good size water bath upright and I may actually want to use two of these.

    I also found this double burner consumer model and one or two others that seem cheap enough to try and these would appear to provide a more stable base for a large turkey pan or similar dish.
     
  24. Photo Engineer

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    Mark;

    How about a fish tank heater and a pump. Fill a tank with water, bring it to the right temp and then place your bottles in it with solutions to temper. This would work. Also a beaker on a hot plate with a fish tank pump to circulate into a larger tank with the chemicals in them.

    Just be careful. A lot of pyrex containers that work well in ovens or microwaves will NOT work on hotplates or the dual units you have referenced above. You can tell which will not work by the statement (NOT FOR STOVE TOP USE OR HOTPLATE USE).

    PE
     
  25. KenS

    KenS Member

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    heating pads

    Mark,

    Take a look at the horticultural type warming pads.... low enough wattage... (and an available thermostat you can purchase) that should allow for reasonable temperature maintenance.

    <http://www.americanhort.com/root.html#Anchor--Pr-7027>

    The thermostats (which one should expect to be 'waterproof' in a horticultural environment) are further down that page...

    Ken
     
  26. markbarendt

    markbarendt Subscriber

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    Thanks PE. I may stick with a metal pan and plastic measuring jugs to start.

    I have tried a modified fish tank heater in the bath along with a hot pad underneath it, they both seem to be made for lower temps and just don't have the oomph needed to keep up with a good size tray at 100; low 90's are workable. This is actually the way I warm my secondary C-41 chems, and RA-4 and LPD developers now.