Temperature Control (and is Ilford right or wrong ?)

[ted_sorensen1]

I have been processing black & white film at home once in a while

for a few years but I am not an expert. I have always tried to

maintain the developer temperature at exactly 20 degrees using a

water bath at 20 degrees. I try to bring the tank to that

temperature in advance using the bath. If I start with the developer

at 20 degrees, I notice that if I measure the temperature after I

pour it out of the tank it is usually slightly above (maybe 21

degrees would be typical). I sometimes try to start a half degree

below to compensate.

 

Then I looked at Ilfords document "PROCESSING YOUR FIRST BLACK&WHITE

FILM" which is available at:

http://www.ilford.com/html/us_english/pdf/Film%20Hobbyist.PDF

 

Excerpts:

 

4 Adjusting and maintaining solution temperature "... Stand the

three containers in a bath of water that is a couple of degrees

warmer than the chosen working temperature of 20?C/68?F."

 

9 Start development "...The developer should start at 21?C/70?F, to

allow for a slight temperature drop during processing..."

 

are these statements right or wrong?

 

Why should the bath be 2 degrees warmer? My room temperature is

about 22 degrees C, so should it not be a half degree cooler, if

anything - or does Ilford assume everyone has cold rooms. Is it a

British thing to have cold rooms?

 

Why should the developer drop during processing? My hands are warmer

than 20 degrees? Is there a temperature drop resulting from chemical

reactions? If so, why do I not read a lower temperature in my poured

out developer?

 

Thanks

-Ted

[__stu_evans]

It's how the Empire dwindled.

[ronald_moravec1]

Ilford must have found film development to be an exothermic reaction at some point. Very ocassionally I use my Patterson System 4 tank and have monitored the temp while the development was taking place with a stem/dial thermometer. I found the reaction to be neither exothermic nor endothermic. Simple English is I think Ilford is whooey.

 

Perfection requires you to bring the tank, film, reel, and all chemicals to 68 deg/20 before beginning processing.

 

The best way to maintain water bath temp is to place the bath on four bottle caps or an upsidedown print tray. This will miminize heat transfer to or from the supporting surface. Start the bath at 67 or 66, add the tank and chemicals, and hopefull will stabalize at 68. Adjust the first time with ice or hot water and start at a different temp the next time.

[John Farrell]

English houses are commonly colder than those in the usa. Standing your chemicals in a bath of water is not going to instantly raise their temperature to that of the bath. The bath will also be losing heat to the cooler atmosphere, remember, while the chemicals warm up.

[robert_davis2]

"My room temperature is about 22 degrees C"

 

Why is your room temp so high? I'd be close to considering A/C at that point-)) And this time of the year 65F/18C is pretty close to normal in the darkroom.

[ted_sorensen1]

Well if you must know, my film developing happens in my kitchen (except of course loading the reels). My thermostat in my house is usually set to around 21 degrees C., but my kitchen is often a touch warmer

[jerry thirsty]

I won't claim to be a hard-core black-and-white darkroom artist, but I've never had the impression that the b&W developing process was so persnickety that a water bath was required. I always set my water temperature to match room temperature, and then assume that the developer is going to rise about 1 degree C due to handling of the tank and the mechanical energy of the agitation. So I select the development time based on the average temperature, or 1/2 degree C above room temp. I never use a water bath for b&w, and so long as the rinse and stop temperatures are reasonably close (within a degree or two or three) to the developer temp, reticulation is not a problem.

 

Personally I prefer my darkroom to be a little on the cooler side, since it's more comfortable to put on an extra shirt than to have to start stripping halfway through a printing session.

[ted_sorensen1]

Thanks everyone... my question is answered. I suppose what I was really asking was:

(a) Was the writer of this how-to article just assuming a cold room in the instructions but forgot to mention that; or

(b) Was there really something specific I didn't know (like development being exothermic, for example).

 

I think that especially given that the article was a beginner "How-to" article, the writer should have mentioned that it assumed a colder room. It could easily lead a beginner to over-develop their film somewhat when working in a warm room.

[al_kaplan1]

The important thing is consistancy from one time to the next. You can change times to compensate for a diferent temperature. If your developer always warms up a degree or two and your negatives are fine, no problem. But if you start out in a warm room one time, a cold room the next you might have problems. I know from experience that Tri-X in D-76 1:1 works fine from 65 degrees f to 82 degrees f, and probably beyond! It's probably MORE important to keep all your chemicals and the wash water within a degree or two of one another.

[nige_buddy]

in winter I might have to warm it up, in summer, cool it down.

[glenn_thoreson]

Personally, I find that if I start at room temperature, usually 68 to 70 F, the chemicals stay pretty consistent on their own. If over 68F, I just adjust time to compensate. That's easiest for me anyway.

[frank.schifano]

My take on Ilford's advice is that it will work if the ambient temperature of the room and the prepared solutions are lower than the desired processing temperature. It also takes into account the fact that your processing tank will be a bit on the cool side. Pre-soaking your film and tank is a good way to get the tank up to processing temperature, but you can also do it by letting your tank sit in the tempering bath along with your bottled working solutions. Plastic tanks will float when not full of liquid, so I just put a weight on top while it comes up to temperature. Stainless steel tanks don't float. Since your space is warmer, it won't work nearly as well. In my case, I do the processing in the basement and for most of the year the ambient temperature is well below the desired operating temperature so I have to warm things up a bit. I use an adjustable and immersible heater in the water bath to keep things stable. When the weather is warmer, I adjust the developemnt times to compensate since it's a real PITA to get things cooled down to 20 deg C. Ilford has a chart on their site here: http://www.ilford.com/html/us_english/pdf/tempconv.pdf and it works pretty well.

 

If there is a temperature change caused by the chemical reaction between exposed film and developer, it is very small. I've not been able to measure any difference with my thermometer. There are two exceptions that I have noticed. Mixing Rodinal concentrate with water seems to raise the temperature of the solution slightly. This is probably due to the fact that Rodinal has a lot of sodium hydroxide which releases heat upon contact with water. The other is a temperature drop when dissolving sodium thiosufate in water to make fixer.

[conrad_hoffman]

Far be it from me to suggest that Ilford is confused, but that doesn't agree with my experience. If everything is at the same temperature, just the heat from your hand during agitation will raise the developer temperature a degree or two if you don't use a water bath. IMO, b&w isn't that fussy, and I typically start development at 68F and finish at 70F. My time has been fine tuned for that range. I suppose you could soak your hand in cold water when not agitating...

 

With enough of a water bath- I sometimes use a deep grey dish tray like you'd find in a restaurant, the temperature won't change much over ten minutes or so, and your hand will have little effect. Any reaction from development itself is too small to worry about, and probably too small for the average person to measure.

[patrick_gainer]

If anything, the energy put into the system by friction of agitation should tend to warm it. I've never noticed an appreciable difference from in temperature over 8 minutes.

[chris_waller]

If my room is a couple of degrees below working temperature, i.e. 18 C, then I start development at say, 20.5-21 degrees C to allow for a drop over 8-10 minutes. But whenever possible I just keep everything at exactly 20 C. I have found that if I keep my hands wrapped around the tank then the temperature rises during development. I would imagne that Ilford is assuming that rooms, particularly in Britain, will be around 16-18 C.

[edward_zimmermann]

"<cite>I would imagne that Ilford is assuming that rooms, particularly in Britain, will be around 16-18 C.</cite>"

<P>

Which makes sense given the traditonal lack of central heating and the use of ambient air intakes to the kitchen <u>as</u> the refrigerator--- and, I'd guess, the assumption that the kitchen is the favorite place for developing film. English homes have tended to traditonally be barely heated and standard home attire included a jacket, perhaps a pullover or, at least, a woolen vest.

[Mike Gammill]

An easy way to cool or warm chemistry before putting it in the tank is to take a pyrex test tube and fill it with ice water or hot water (depending on whether you want an increase or decrease). Use it to stir the solution until you get the temperature you want. If you have long developing times you can partial immerse the tank in a heated or cooled water bath to keep uniform temperature.

[kirk_keyes]

I beleive it has to do with the use of Lucas Electrics - ask any fan of British cars or beer.

[lowell_huff1]

Photography is supposed to be FUN not WORK ! I have a conversion chart for time and temperature changes. contact me and I will send the chart. Lowell

askus@claytonchem.com

[al_divenuti]

>>Ilford must have found film development to be an exothermic reaction at some point.

 

Perhaps, but stainless steel tanks also conduct heat reasonably well and it may be enough to heat the liquid a degree or two using a small tank and agitation by hand for 60 seconds initially and 10 seconds each minute thereafter...body temp is typically close to 16 or 18 degrees C higher than room temp, after all.

[discpad]

I use a Jobo for color & B&W processing; and for B&W I use 24.7C/75F -- This is slightly above ambient, and assures that the heaters are "working against" ambient.<br><br>

Also, check out the massive dev chart at: <br>

http://www.digitaltruth.com/devchart.html

<br><br>

Cheers! <br>

Dan<br>