Thermometers...

Discussion in 'Darkroom Equipment' started by Markok765, Dec 9, 2006.

  1. Markok765

    Markok765 Member

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    I have a few thermometers, some digital some analog, and im wondering what you guys use?
    I have had 3 digital thermometers break, one wont turn on, even with a new battery, one stays at -49C and one is off by 10C. These are all high quality ones from the food industry
    I have 2 analog thermometers, one stick style and a dial style one.
    I use the dial one cuz of its speed.
    So, what thermometers do you use?
    I do B&w development
     
  2. Ole

    Ole Moderator Staff Member Moderator

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    Most of the time, unless I'm using the JOBO machine, I use my left index finger...

    I have several exellent thermometers, even a digital one somewhere. But I know exactly how 20C feels on my finger, and I seem to be accurate to within less than half a degree. That's close enough.
     
  3. Jim Noel

    Jim Noel Member

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    My luck with digital therometers has been similar to yours so now I only use analog dial ones. I also have a Kodak mercury process thremometer to which I adjust all others.
     
  4. Jim Jones

    Jim Jones Subscriber

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    I've had trouble with analog dial thermoters, and now sometimes use spirit or mercuy (don't tell the environmentalists!). Usually I try to keep chemicals, wash water, and film tanks at room temperature, and just look at the wall thermometer.
     
  5. Craig

    Craig Subscriber

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  6. konakoa

    konakoa Member

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    I have two Kodak Deluxe glass thermometers. One is my working thermometer, the other is a spare in case I drop the first. These are alcohol, not mercury, thermometers and are claimed to be accurate to half a degree. They've been the best I've ever used, and should never drift in sensitivity. I still see them new at B&H.

    I had a stainless dial-type for a few years, yet somehow (unknown to me) the stem came loose which caused the needle inside the case to spin freely. Didn't know it until I developed a batch of negatives and they came out virtually clear. N-9 developing, anyone?
     
  7. matti

    matti Member

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    I would like to get one that can take stirring better than my cheap ones.
    /matti
     
  8. johndeere

    johndeere Member

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    I consider temperature a key component in the processing cycle. A change in the temperature changes the total complex chemistry of the developing process. While I may be extreme in my thinking the results speak greatly for keeping those temperatures in check.

    I do trust my Kodak Process Thermometer to keep everything in order. In addition I use several Kodak glass type thermometers after making sure they are calibrated with my Kodak Process Thermometer.
     
  9. ricksplace

    ricksplace Member

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    I have a cheap digital I bought at a surplus store about 10 years ago for about $3. It has a long stem on it perfect for reaching into tanks. The dang thing is spot on to my Kodak lab grade mercury thermometer. Go figure.

    So I use the digital and check it once and a while with my mercury glass thermometer.
     
  10. Justin Cormack

    Justin Cormack Member

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    I have never had any reliability problems with my digital pH meter (which also does temperature) - its a lab one but wasnt expensive (and useful for other things too, like stopbaths, and cheese making). Though I dont tend to measure much. Unlike my digital timer which has died, unclear if its a battery issue or more serious. Think I need a nice analogue stopwatch.
     
  11. Bruce Osgood

    Bruce Osgood Membership Council Council

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    I feel any thermometer that can be 'adjusted' is inherently wrong and I use one to determine water temperature on the hot plate when brewing stock chemistries. But when it comes to Jobo processing or making a working solution from stock I use the non-mercury glass tube similar to the one Craig mentions in his post.
     
  12. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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  13. PeterB

    PeterB Subscriber

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    Accuracy of thermometers

    Hi Bruce, why do you say that?

    If anything, a thermometer that can be adjusted is easier to calibrate. Certainly an adjustable themrometer is easier to "knock" out of cal. but usually there is a locking nut to stop that happening.

    Nothing holds its accuracy forever which is why even Liquid-in-glass (LIG) thermometers require checking. If you think it is not possible for an LIG thermometer to go out of cal, think again !! See here and here for my previous posts on the topic.

    regards
    Peter
     
    Last edited by a moderator: Dec 11, 2006
  14. ijsbeer

    ijsbeer Member

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    I've got an old patterson thermometer from my dad. he used it in the 70's. its old but its in perfect working condition. it's made of glass to breakable yes but it does the job very good.

    to Ole, my indexfinger is not capable of telling that my temperature is 20 or 24 degrees when developing film. :wink:

    Reinder
     
  15. Gerald Koch

    Gerald Koch Member

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    I have been using the same digital thermometer for the past 4 years. It is one used by food inspectors that I paid a whopping $13 for. I have checked it and it is quite accurate.
     
  16. Kilgallb

    Kilgallb Subscriber

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    To calibrate a digital thermometer, place it in a glass of ice water. It should read exactly 0C
     
  17. Ole

    Ole Moderator Staff Member Moderator

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    I've checked repeatedly against a good (mercury) lab thermometer, and "a little too warm" is about 20.4C, "getting cold" is about 19.7C. 24 degrees is definitely hot! Since that's about the precision I expect from a decent thermometer, I keep mine safely stored away except for occasional "index checks".

    In a way i'm just using a real, indexed, digital temperature sensor :smile:
     
  18. filmnut

    filmnut Member

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    I use a medium priced dial one that I got from a photo store. I have access to a Kodak mercury process thermometer, and when compared to that, it is right on. I have found that the dial ones, which I find easier to use, are more suseptible to a knock, but of course glass will break. The difference being you can bang your dial themometer out of whack, but it if still works you may not realize it is out a few degrees untill it is too late, but if you break the glass, you know you need a new one!
    All of these should be checked from time to time, but mainly they need to be consistent. If it is one or two degrees high or low, it won't really make a difference, as long it and your method is reliable.
    Refering to another point that a previous poster mentioned, the mercury themometer that I check against is has a stainless steel surround, which makes it safer, and it also can be used as a stir stick. I have no idea if these can still be bought from Kodak, but they were available from them in the past.