Water temperature

Probably hear lots of this, but I've been guessing my water temperature for a while now, always leaning towards what my body feels is lukewarm.

Recently I bought a glass thermometer to standardize my process and keep it consistent. It sits at 78F when just laying around and only goes to 68F if throw it in nothing but colder water from my tap. Anything other than straight cold water from the tap puts it at 80F or higher.

I developed a roll with it and it seemed far underdeveloped. Is it possible that my thermometer is just wrong?

Drop it in a glass of ice water and then a pot of boiling water. Give it a bit of time so there is no thermal shock to break the glass though. Check both temps.

Newt_on_Swings said:

Drop it in a glass of ice water and then a pot of boiling water. Give it a bit of time so there is no thermal shock to break the glass though. Check both temps.

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What temperatures should I get from both of them?

A thermometer is one of the pieces of equipment that you will always need and the right temp is crucial enough not to rely on just any thermometer. If I have understood your description of your thermometer it sounds unreliable. Buy a photographic thermometer certified accurate to within 0.2 degrees centigrade

They aren't that expensive( and a lot cheaper than ruining film development) and will last a lifetime. I am sure you will feel it is too dangerous to guess quantities of liquids and use proper beakers calibrated for ccs or fluid ozs so why not eliminate guesswork when it comes to temperature as well

pentaxuser

Newt_on_Swings said:

Drop it in a glass of ice water and then a pot of boiling water.

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Boiling points are dependent on altitude or current atmospheric pressure and are not accurate unless you make the appropriate correction. At 5,000 feet water boils at 203 F.

I'd be surprised if what your body feels is lukewarm is low enough. Your body temperature is 98F, so 68F is going to feel quite cold.

mcgrattan said:

I'd be surprised if what your body feels is lukewarm is low enough. Your body temperature is 98F, so 68F is going to feel quite cold.

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Absolutly-- 68 feels downright cold.
The OP definitly needs to invest in a quality thermometer.

Human sense of temperature can be fooled very easily and is very unreliable. As it stands, you have no standard to go by....

If you are at all serious about getting good results from your film processing, you should buy one you can trust. There is no need to go overboard and get a NIST certified meter. 20 to 30 dollar kind from photo stores are just fine.

I taught a class in physical chemistry. One of the experiemnts was the Carnot cycle of a rubber band. The most sensitive part of the human body to gauge temperature is on the underside of the lower lip. This spot was used by the students to see if the rubber band got cooler or hotter. If you stretch the band it gets warmer when you relax the band it gets cooler. Stretching the band forces the rubber molecules to become aligned with each other. This reduces the entropy releasing heat. When relaxed the molecules become randomized which requires the absorption of heat and the band gets cooler. To try this out you need a rubber band that is at least 1/4 inch wide.

The body is very good at detecting changes in our surroundings, like temperature, humidity, etc. We know very rapidly that there is a change.
However, and this is a big deal, we are terrible at telling how much with any sort of consistency. This is why very smart people invented things like thermometers.

Buy a good thermometer, and develop your film at the same temperature - every time. Unless you don't care about the end results.

I just tried to get my lower lip into my developing tank and now I'm writing this from hospital.

pdeeh said:

I just tried to get my lower lip into my developing tank and now I'm writing this from hospital.

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Nice one

pentaxuser

You can develop black and white film at many different temperatures, but you'll make yourself crazy if you don't pick one and stick to it.

68 degrees F (20 degrees C) is the usual recommendation. Even a cheap thermometer will be reasonably repeatable, even if not particularly accurate. It doesn't cost much to get a reasonably accurate thermometer.

For most of the year, my tap water is warmer than 68 degrees. No problem. I use standard stainless tanks (better thermal transfer than plastic) with leakproof lids. I use an inexpensive styrofoam minnow bucket to hold the water bath. It's thick styrofoam, so it holds the temperature very well once I get it stabilized.



I throw a few ice cubes in the water and swirl it around until my thermometer hits 68 degrees. I pull out any remaining ice cubes and put my graduated cylinder full of developer in the water to acclimate. After I load the film into the tank, I float the tank in there too.

When I'm ready to go, I pour the developer into the tank, give it a few inversions, and drop it into the water bath. Now it sinks to the bottom. Every 30 seconds, I lift it out, give it two inversions, and back into the bucket of water it goes.

The stop bath, fixer, hypo clearing agent, and wash temperatures aren't so critical. Just keep them reasonable within a few degrees of the developer temperature.

Just out of curiosity, do you think there is a way to get water to a repeatable temperature without using a thermometer?

Just supposition, but, for instance, what if you took a measured amount of water in a styrofoam cup and dropped in ice cubes, one by one, and stirred until the last cube doesn't completely melt? (Or takes longer than a minute to melt?)

Using the same idea as the "Three Missisippi" test when trying to determine when your barbecue grill is hot enough to cook: Hold your hand over the center of the grill, about a foot above the fire and count, "One Mississippi...Two Mississippi...Three Mississippi..." until you have to pull your hand away. If you have to pull your hand away at "Three Mississippi" the fire is ready.

Just wondering... What do you think?

Worker 11811 said:

Just out of curiosity, do you think there is a way to get water to a repeatable temperature without using a thermometer?

Just supposition, but, for instance, what if you took a measured amount of water in a styrofoam cup and dropped in ice cubes, one by one, and stirred until the last cube doesn't completely melt? (Or takes longer than a minute to melt?)

Using the same idea as the "Three Missisippi" test when trying to determine when your barbecue grill is hot enough to cook: Hold your hand over the center of the grill, about a foot above the fire and count, "One Mississippi...Two Mississippi...Three Mississippi..." until you have to pull your hand away. If you have to pull your hand away at "Three Mississippi" the fire is ready.

Just wondering... What do you think?

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If your home stays at a constant temperature then keeping a bottle of water stored with your chemicals will give you repeatable temperatures. That is what I do. I still measure the temp before developing but it is always the same.

4strinbass said:

What temperatures should I get from both of them?

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0 and 100 Celsius. 32 and 212 Fahrenheit. Yup and it's for sea level only though. If they hit both points your thermometer should be accurate. A digital thermometer is also quite cheap an provides fast results too but can be tricky to judge how fast something is cooling or heating when not looking at a scale or dial.

Thomas Bertilsson said:

Buy a good thermometer, and develop your film at the same temperature - every time. Unless you don't care about the end results.

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+1

And a good thermometer doesn't even have to be expensive. A couple of ruined or badly processed rolls of film will pay for one.