How Hot the Water to Raise Developer Temperature Quickest?

bags27 · May 5, 2022

Background: in the winter, we sleep with the temperature set at 56 deg. When my wife wakes up, she wants it 68, quickly. So, she turns the dial to 78 or so, and then forgets about it. The temperature soars. I get up much later and turn the dial to 68. I tell her: just set it for 68, since setting it higher won't get it to 68 more quickly and we're wasting money. We've been having that conversation for almost 42 years now....

When trying to warm up developer quickest, does it matter if the surrounding water is much hotter than the targeted temperature or just the temperature that I want the developer to get at? Let's say I'm using a sous vide in a plastic tub and immerse my developer and blix, aiming at 102 deg. For the purposes of getting the chemicals to the right temperature the quickest, does it matter whether I set my sous vide for 102 or set it a lot hotter and therefore make the water much hotter than 102?

(I realize blix doesn't need to get to 102; I also don't care what the temperature of the water is after I lift out the developer & blix: I don't put the Patterson tank in it between agitations.)

I really struggled with high school chemistry class and now I know why.....

Thanks!

Doremus Scudder · May 5, 2022

Hotter water will get your chemicals to temperature more quickly, but you then risk overshooting the target temperature. It just takes a minute or two to get significantly overheated...

My recommendation would be to set your temperature bath at the desired temperature and then have a little patience. It will be slower, by a bit, but then you won't have to watch it like a hawk. Get your chemicals in the bath early and spend time setting up everything else while the chemicals are getting to temperature.

Best,

Doremus

wiltw · May 5, 2022

"The rate of heat transfer between two surfaces is equal to the temperature difference divided by the total thermal resistance between two surfaces."

The flaw in wife's thinking comes with assumption that hot air comes out of the vent at a higher temperture when the thermostat is set to 75 vs. only set to 70...the thermostat merely changes the temperature at which the output is shut off (sooner when set at 70 than when set at 75...the hot air comes out of the vent at the same temperature regardless of the thermostat setting! --easy to prove. Set thermostat to 70 when room is 68, measure air temp from register...increase thermostate to 75 and see that the register air temp is no different!

OTOH, if the temperature in the room is 75, the rate of heat transer is faster to her cold body, than if the room were only 70. Raising her body temp one degree happens faster in the warmer room. I think that is why women fool with the thermostat so much, while men leave it alone...which is why phony thermotats exist on walls of public places, it gives the psychological control to women even though it changes nothing.

Back to darkroom chemistry control of temperature...a warmer water bath will warm the cold developer faster, but you have to pull the developer out of the bath or else it will not be at your desired end temperature, but overshoot that temp. I agree with Doremus...water bath at correct end temperature, set the stainless tank full of developer in the bath, walk away and get something to snack on, then drop the reel into the tank (in the dark, of course) and start the timer...

Sirius Glass · May 5, 2022

bags27 said:
Background: in the winter, we sleep with the temperature set at 56 deg. When my wife wakes up, she wants it 68, quickly. So, she turns the dial to 78 or so, and then forgets about it. The temperature soars. I get up much later and turn the dial to 68. I tell her: just set it for 68, since setting it higher won't get it to 68 more quickly and we're wasting money. We've been having that conversation for almost 42 years now....

The first part only: The furnace has a limited rate that it can heat the room or house and setting the temperature higher will not heat the house faster. The furnace allows heats at a constant rate.

The rest is adequately addressed above.

Vaughn · May 5, 2022

But the wife is also correct. Such is life.

The house is 56F. Allowing the air in the house to raise above 70F for awhile will help heat the walls. floors, ceiling and contents of the room to 70F faster.

If the heater shuts off when the air first gets to 70F, the walls and furniture will still be in the 60s and will still suck energy from you (and one's wife).

So for your developer -- if the container and surroundings are close to 102F, you are fine as soon as the liquid hits 102F...otherwise, a little hotter to counter the temp drop after turning off the heat.

bernard_L · May 5, 2022

What Doremus said, given that you use a constant-temperature bath. There is a different approach: to let your photochemical bottles exchange heat with a mass of water
- inside a decently insulated enclosure (picnic ice chest, e.g.)
- with a given initial temperature
Then you can --in principle-- converge to a known temperature provided you use a simple rule, that I'll illustrate with a numerical example rather than with equations.
Say your chemicals, 3 litre volume (dev-stop-fix) are at 16°C, and you need them at 20°C; they are 4°C too low. Say, also, your picnic chest allows for 5 litre warm water. The temperature excess of your warm water above the target should be
DeltaT=(3/5)x(20-16) = 2.4, so you need warm water at 22.4°C. In the real world, you need more, because:
- heat losses;
- heat capacity of bottles and of the inner wall of picnic ice chest.
Rather than embark into calorimetric calculations, a little experience will tell you how to adjust the factor (3/5) to a real-world value. The advantage of this method is that cold chemicals and warm water converge to a common in-between temperature with no risk of overshoot. Keep in mind that plastic bottles have low conductivity; glass is better in that respect.

Another approach would be a modification of the sousvide heater where the temperature sensor would be inside one of your photochemical bottles (the heater still in the water bath), and the setpoint of the sousvide would be your desired temperature, no more, no less. Some tuning of the PDI parameters of the thermostat would be required.

Final note. Presumably if your chemicals are below processing temperature, so is the developing tank. So, during the first minute or so of processing, the dev temperature will drop as it exchanges heat with the tank. To counter this you need either (a) to pre-warm the tank; or (b) to start from a dev temperature above the target.

Donald Qualls · May 5, 2022

I would add to this (water bath at goal temp) a device to keep the cold developer from pulling the bath temperature below the goal. I use a cheap sous vide (made for slow-cooking foods sealed in plastic, it can maintain temp to +/- 1 F over a huge range, as long as the set temp is above ambient). Same (type of) device Cinestill sells for $150, but at less than 1/4 the price, in my case.

MattKing · May 5, 2022

First: always tell your wife that she is right. This will ensure lots more warmth ;
Second: invest in a programmable thermostat;
Third: find a cooler that your plastic tub can sit in, so you lose less heat overall, and then set your temperature for the target temperature or slightly more.
And Fourth, it seems to me that this belongs in the Colour Film sub-forum, so I'm moving it there.
Hope some of this helps.

Sirius Glass · May 5, 2022

MattKing said:
First: always tell your wife that she is right. This will ensure lots more warmth ;

Especially when she is not.

pentaxuser · May 5, 2022

wiltw said:
The flaw in wife's thinking comes with assumption .....

OTOH, if the temperature in the room is 75, the rate of heat transer is faster to her cold body, than if the room were only 70. Raising her body temp one degree happens faster in the warmer room. I think that is why women fool with the thermostat so much, while men leave it alone...which is why phony thermotats exist on walls of public places, it gives the psychological control to women even though it changes nothing.

Is there a flawed kind of reasoning built into females in general in the matters like this that we males have to just allow for? I am sure you didn't mean this but I have to say that the way you have phrased your response it does sound that way

pentaxuser

gone · May 5, 2022

Developer chemicals will react like most other chemicals in regards to heat, they will be more active in warmer temps and the other way round in cold temps. Being from the South, I like my my bedtime, daytime, and all time temps around 80-84, but I generally (not always) will bring the water bath for my developer to around 72 for film developing.

Whether or not the developer in the container actually gets to that temp is another story. I often just use the chemicals at the home temperature because I don't want to wait around, and honestly, I haven't seen much, if any, differences between the two styles of development. For prints I don't do anything, they get developed at whatever the ambient temperature is.

wiltw · May 5, 2022

pentaxuser said:
Is there a flawed kind of reasoning built into females in general in the matters like this that we males have to just allow for? I am sure you didn't mean this but I have to say that the way you have phrased your response it does sound that way

pentaxuser

If a woman gets the room to 75, the room takes longer to warm, yet the warmer room warms HER faster!

No false logic, other than the fact that heat comes out of the register at the SAME TEMP no matter how the thermostat is set...it does not warm the room faster (degree rise per minute is the same regardless of thermostat setting) ...the heater merely runs LONGER in order to get to a higher temperature.

There was ZERO judgemental color in my earlier post of this; I simply echoed facts. A man could have the same flawed logic about 'higher thermostat setting warms the room FASTER'. It is an observed fact that women in offices try to adjust the thermostat up and down with greater frequency than men do. The fake thermostat is meant to appease genders equally; women merely try to adjust it more often. Woment more often complain about the temperature because MEN mostly set the temperature, not as warm as women prefer!

In fact, recent research found that women performed better on both math and verbal tasks as temperature increased, while the opposite was true for men. The effect wasn’t huge: for each one-degree-Celsius increase in temperature, women answered about 1.75% more math questions correctly and 1% more verbal questions correctly, while men answered about 0.6% fewer correctly in both categories. Temperature preference is biological, not sexist.

pentaxuser · May 5, 2022

Thanks for the reply. I suppose it was the phoney thermostats that seemed to be put on walls of public buildings specifically for females' pyschological control that is an illusion that made me wonder about whether there was a danger of a kind of gender stereotyping

pentaxuser

wiltw · May 5, 2022

pentaxuser said:
Thanks for the reply. I suppose it was the phoney thermostats that seemed to be put on walls of public buildings specifically for females' pyschological control that is an illusion that made me wonder about whether there was a danger of a kind of gender stereotyping

pentaxuser

No the phony thermostats are not aimed to one gender, it is meant to neutralize efforts by women to move the temperature up and efforts by men to move the temperature down. If that were happening all day, it would increase heating and air conditioning costs as the genders adjusted temperature. As I said, men set the temp for an office, and because it is generally cooler than women would like, it is THEY who are trying to adjust the thermostat up!
If a woman controlled the temperature setting of the office, the men would want it cooler and they would be the ones getting up and tweaking the thermostat. Ever notice how warm passenger jets are sometimes? And sometimes they are chilly? The same thermostat wars.
The phony thermostat provides folks with a placebo adjustment. capability.

pentaxuser · May 5, 2022

Thanks for your second reply This adds considerably more information for clarification of gender neutrality than I thought your original post.

pentaxuser

Sirius Glass · May 5, 2022

wiltw said:
No the phony thermostats are not aimed to one gender, it is meant to neutralize efforts by women to move the temperature up and efforts by men to move the temperature down. If that were happening all day, it would increase heating and air conditioning costs as the genders adjusted temperature. As I said, men set the temp for an office, and because it is generally cooler than women would like, it is THEY who are trying to adjust the thermostat up!
If a woman controlled the temperature setting of the office, the men would want it cooler and they would be the ones getting up and tweaking the thermostat. Ever notice how warm passenger jets are sometimes? And sometimes they are chilly? The same thermostat wars.
The phony thermostat provides folks with a placebo adjustment. capability.

Phony thermostats increase the perception of control.

grat · May 7, 2022

When I bought my current house, it still had the original 30 year old HVAC system, with an 80,000 BTU gas central heater, in what is a relatively small concrete block structure. The heat would come on, ridiculously hot air would blow out in a force 10 gale for about 2 minutes until the thermostat's temperature was raised, and the system would shut off. With 10 minutes, the air was cold throughout the house again, because while the air temperature would go up, the structure would remain cold.

One of my first major projects was a replacement of the HVAC system-- and a long discussion ensued, involving a completed schedule J, a 45,000 BTU gas heater, a variable speed blower, and a 2 stage compressor (SEER 16 instead of SEER N/A). My house is now warmer in the winter, colder in the summer, and I saved enough on the monthly utility bill to pay for the system in 3 years.

Interestingly, while I have a programmable thermostat, I don't use it that way-- since I'm in Florida, most of the time, it's better to run the small compressor stage to maintain the temperature at a comfortable level, than it is to let the house get warm during the day, and then kick on the large compressor stage to cool it down at the end of the day.

Sometimes, less is more.

@OP you have sous vide. Set it to the right temperature, and let it sit until the chemicals inside your bottles have reached temperature. Raising the water bath will heat up your chemicals faster, but unless you're directly monitoring the temps inside the storage bottles, you will overshoot your desired temperature, and spend more time cooling it down. Further, without using ice, the bath is going to be more difficult to cool back down to the target temperature. I tend to set the sous vide about 1-2 ℉ higher than target temperature, since I assume I'll lose a degree or two when pouring the developer into the tank (I preheat the tank with a pre-wash at target temperature).

mshchem · May 7, 2022

I've had a dedicated darkroom microwave for 20 plus years. Very short, 10-15 seconds ,open beaker. Works great.

otto.f · May 7, 2022

The thing is, that cooling down your liquids in the dark room is much more difficult than warming them up. So once you’re over the desired temperature because you’re in a hurry, you’ll have a longer time coming down again. That is because you’re still on the lower side of the scale between room temperature and boiling water.

bags27 · May 7, 2022

Thanks everyone for wit, wisdom, and science (on the last: thanks especially to Bernard L). I do use my sous vide effectively, since I have paid the time price of overshooting temperature and know that, even with ice cubes, it's a real pain.

To put it practically, if my basement temperature and developer are 60F and my target is 102, I can put (say) 110F tap water into the tub and let it cool gradually with the sous vide set for 102 to support that temperature as the cooler chemicals meet the warmer water. That will accelerate the chemicals to 102 but almost certainly not overshoot.

2 quarts (Cinestill 2 bath) of chemicals in 10 quart tub. Chemicals @ 60 and target 102
2/10 (chemicals to water) x 42 (temp delta) = 110 F.

As Bernard L pointed out, other variables will cause more heat loss, so it's ballpark, but that helps assure the chemicals won't overshoot. There won't be a significant drop in the developing tank, as I do pre-soak but don't put the tank back in the water between agitations (I used to but find no difference in resulting negatives).

So, assuming chemicals at 60, pouring in water ~8 degrees above target temperature accelerates the process with little chance of overshooting. Do I have that right?

Saving precious seconds!

foc · May 8, 2022

I will be installing a phony thermostat in the house tomorrow.

bernard_L · May 8, 2022

bags27 said:
Do I have that right?

sounds good to me.

bags27 said:
2 quarts (Cinestill 2 bath) of chemicals in 10 quart tub. Chemicals @ 60 and target 102
2/10 (chemicals to water) x 42 (temp delta) = 110 F.

Final result correct. For the record, and for those reading this thread in the future, 2nd line should read:
2/10 (chemicals to water) x 42 (temp delta) = 8.4°F; added to target 102 gives (approx) 110°F.

Tepid water; the best invention since sliced bread!

bags27 · May 8, 2022

Thanks so much for this, Bernard.

I tried this yesterday and it was a nice, gentle, unhurried, but also not overly long approach to getting to target temp.

Chan Tran · May 8, 2022

bags27 said:
Background: in the winter, we sleep with the temperature set at 56 deg. When my wife wakes up, she wants it 68, quickly. So, she turns the dial to 78 or so, and then forgets about it. The temperature soars. I get up much later and turn the dial to 68. I tell her: just set it for 68, since setting it higher won't get it to 68 more quickly and we're wasting money. We've been having that conversation for almost 42 years now....

When trying to warm up developer quickest, does it matter if the surrounding water is much hotter than the targeted temperature or just the temperature that I want the developer to get at? Let's say I'm using a sous vide in a plastic tub and immerse my developer and blix, aiming at 102 deg. For the purposes of getting the chemicals to the right temperature the quickest, does it matter whether I set my sous vide for 102 or set it a lot hotter and therefore make the water much hotter than 102?

(I realize blix doesn't need to get to 102; I also don't care what the temperature of the water is after I lift out the developer & blix: I don't put the Patterson tank in it between agitations.)

I really struggled with high school chemistry class and now I know why.....

Thanks!

When the room temperature is 56 and you turn the thermostat to 68 or 100 it gets to 68 at the same time not faster. The reason? When the room temp is below the set temp the furnace is putting out as much heat as it can until the room temp gets to the set temp. For the water bath is different if the surrounding water is hotter than the developer will get to temperature quicker.

wiltw · May 8, 2022

Sirius Glass said:
Phony thermostats increase the perception of control.

That is why folks who drive on roads might choose not to fly...commercial flying is statistically SAFER than being on the roads. But folks have lost all control while flying.
...not speculation on my part.

Is Air Travel Safer Than Car Travel? | All Getaways

Air travel accidents are heavily publicized and can cause fear for passengers. When comparing risk assenssment though find out if air travel is actually riskier than travel by car.

traveltips.usatoday.com

"Statistically speaking, flying is far safer than driving. However, it may feel more dangerous because risk perception is based on more than facts, according to David Ropeik, risk communication instructor at Harvard School of Public Health. Driving affords more personal control, making it feel safer."

How Hot the Water to Raise Developer Temperature Quickest?

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