Best way to heat up Chems

jeroldharter · Jan 25, 2009

If you live in the UK you might be able to find a Kaiser Dish Warmer which is a water resistant hot plate down rated to photo temps rather than cooking or lab temps.
The cheapest solution is an inexpensive aquarium heater in a water bath. But the response time is weak so it would be best to put the chems in the water bath the night before so that the temperature equilibrates.
Recirculating water baths are very nice but expensive. Sometimes they come up used for as little as $50. I have an old one that works great.
You can also buy an immersion heating element (Dev-Tec?) that is like a high powered aquarium heater that works much faster. I use one with a small submersible aquarium pump to circulate the water in a large, shallow tub .
Another alternative is a Jobo TBE tank which is a big plastic tub that holds 12 1 liter Jobo bottle and has a thermostat. Works very well for holding volumes of developer or "dilution water" for bigger developing runs. They sell on Ebay but are usually very expensive.
You could use stainless developing tanks filled with hot water and others filled with ice to manually adjust the temp of a water bath.

VaryaV · Jan 25, 2009

I inherited this water bath my dad used to use for heating chemicals in the biology lab. It has become indispensable.
American Scientific and Fisher Scientific both made them.

Larry Bullis · Jan 25, 2009

John Shriver said:
Stainless steel containers transfer heat so much faster than plastic. When I'm developing T-MAX films, I want the developer at exactly 68F. So I pour it in an empty Nikor tank, say the Q15 two reeler. Then I put it in a larger diameter Nikor tank (one of the ones for the six-foot or 220 reels) with hot or cold water, swish it about, and watch the thermometer.

That tempering step would be infuriatingly long in the plastic sixteen-ounce measuring cups I use to hold developer, stop, and fixer.

Not only to SS containers transmit faster, but they don't hold the heat very long. If you use hot water and immerse a plastic tank in it, you can heat the chemical; it will take longer, and after it gets up to temperature, it will continue to heat, so it is very easy to end up with the chemical too warm.

I use a tray of hot water. I dip the stainless tank in the water, lift it out, and stir the chemical with the thermometer. Unless there is a big temperature differential, I don't stir while the ss tank is actually in the hot water.

It is very easy to get the temperature right, and it doesn't keep warming after I'm done.

bobwysiwyg · Jan 25, 2009

VaryaV said:
I inherited this water bath my dad used to use for heating chemicals in the biology lab. It has become indispensable.
American Scientific and Fisher Scientific both made them.

An outfit called Shellab still makes similar devices. In a size similar to what you have would be quite pricey. You have a great find there.

clayne · Jan 25, 2009

Never had a problem with varying temperatures of standard chemicals. They're usually within 6-8C of each other, but mostly room temperature.

As far as developer itself goes, I've also never had a problem with this formula (which works with google calculator as well):

new_time = standard_time * e(-0.081 * (cur_temp - 20))

Larry Bullis · Jan 26, 2009

clayne said:
Never had a problem with varying temperatures of standard chemicals. They're usually within 6-8C of each other, but mostly room temperature.

As far as developer itself goes, I've also never had a problem with this formula (which works with google calculator as well):

new_time = standard_time * e(-0.081 * (cur_temp - 20))

6 to 8 seems like too wide a range.

Also, I don't think it a good idea to use different temperatures because many developers have more than one reducing agent. Not all of the agents respond to temperature the same - temperature effects their activity. That can result in the agents not working in balance as they are designed.

My opinion, of course, so if it works for you withing your acceptable quality standards, I can't argue. I adjust the temperature to be on the safe side.

katphood · Jan 27, 2009

I keep everything in my garage. First, I put my two thermometers in a beaker of water (used for prerinse and stop) and my beaker of dev. Then I load my reel(s). Third, I check the temp. If its close to 68F / 20C, its easier to not bother heating and just adjust the times. If its far off (like it is now in January) I put hot water in a bucket, put my beakers of dev, stop / pre-rinse, and fix into the hot water and watch closely. When the temp starts rising, I pull the beaker out about the time it gets to 64. Sitting on the table, it normally keeps rising to right about 68F.

Lately, I've been washing direct from the tap, just judging temp with my fingers to get it about 68F. I rinse for about five minutes, and viola -- negatives.

katphood · Jan 27, 2009

I should have added a couple of things. One, as you are heating or cooling, stir occasionally so that your thermometer is measuring a hot or cold spot.

Speaking of cooling, I found ice water much, much more effective than just ice.

Best way to heat up Chems

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