Rule of thumb - development times

[steven_palmer1]

Development times are usually given for a temperature of 20C (68F)

but my tap water usually sits at 19C or 18C depending on which tap.

I was wondering if there is a rule of thumb regarding increasing or

decreasing development times for each degree away from the standard

20C. How would I calculate the change in development with different

dilutions? As a percentage of the total time at 20C? ie:

development times for Rodinal 1:25 @ 19C to Rodinal 1:100 @ 19C

compared to the standard times for each dilution at 20C. I hope

this makes sense.

 

Thanks for your help.

[rowland_mowrey]

Steve;

 

Kodak has published nomograph(s) for most of its products as to how they function over a range of temperatures, but I don't know of any for other manufacturers.

 

IDK if they would apply from EK developers to any other developer.

 

Let me know if you want to try and I'll scan one in for you and let you be the guinea pig ~if you wish~...

 

Ron Mowrey

[pat_wilson1]

Steven, this doesn't answer your question really, however consistancy is very important. If you develop at 19C consistantly, you can modify your development time based on the results you get. Personally, I'd throw about 10% onto the dev time and see what happened. Consistancy and notetaking...very important.

[macgregor_anderson]

This chart may be helpful. It's best to test for yourself, but in a pinch...

 

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

 

It doesn't answer your more complex question regarding dilutions. I'd suggest checking the developer manufacturer's website along with the film manufacturer's website and comparing any info you can get. At some point, I'd just test for myself. This isn't so hard if you haven't done it.

 

As an aside, I change developer/etc. temps using a ziploc plastic bag filled with ice or hot water. You can move the temps a few degrees easily and in just a few minutes.

 

Mac

[john_shriver]

<p><a href="http://www.ilford.com/html/us_english/pdf/tempconv.pdf">Ilford's Nomograph</a>.</p>

[jorge_oliveira2]

Here's a lik to Ilford's time/temp chart:

 

http://www.ilford.com/html/us_english/pdf/tempconv.pdf

[jimvanson]

I'm a hardcore Rodinal @ 1+100 guy. I've developed many hundreds of rolls using it. When I first started out I tried to cool everything down to 68 degrees and then go from there. I quickly found that doesn't work for me.<P>Now I use chemistry stored at ambient temp. My liquid developer & water for mixing it is usually 70/71 degrees. So is my premixed fix. I don't use stop, instead I rinse with 4 rinses of ambient temp water from another jug.<P>I use Ilford's time/temp table to convert the suggested 68 degree time to my ambient temp time. Works slick.<P>I set the final wash water running towards the end of my fixer cycle. It's set at my working/ambient temperature plus/minus 5 degrees.

[lex_jenkins]

Here's a quickie temperature conversion graph in .gif format.

[steven_palmer1]

Thanks everyone. This should be enough to get me started. I try to keep things consistant but its Winter here in Australia, (if you can call 22C days Winter) and I know my tap water temperature will surely rise as Summer approaches. I guess I'll just make the adjustments as the temperature rises and see how it goes. Thanks again.

 

Steve

[gareth_harper]

I always develope at 20 degrees C. I use distilled water for the developer. I live in Scotland so the temperature of my stored water can vary between 12 and 25 degrees in the house depending on time of year. I simply place the jug of developer in a sink of hot or cold water as appropriate until I get my 20 degrees C. No calculations required.

For washing the film in winter I cool the film in two or three stages by mixing hot and cold tap water and letting the film sit for a minute through each stage until washing in tap water often not that much above 0 degrees C.

[nige_buddy]

Steven, you aren't in my part of Australia! My water is coming out of the tap at 13C at the moment! (I've got a inline temp gauge on it... $15 at Jaycar!). I overcome this, and 26-28C water in summer, by preparing a bucket of water at 20C and using that to mix my developer (with the addition of some cold from the fridge or hot from the tap depending on developer in use i.e. a 1:1 dilution will a require different method to a 1:100 one) Since the room will be a reasonable temp, the temp in the tank won't usually change much, and if it does, I'll sit the tank in some hot or cold to suit to stabilise the temp. I may make a slight development time alteration, but usually not. I think you can become a bit obsessive with these things.

[steven_palmer1]

Nige,

 

it sounds like you are a bit further South than me. I'm in Brisbane so as you know "Winter" is very mild. Summer, however, is hell.

 

Thanks, everyone for the suggestions.

 

Steve

[chris_waller]

As a rule of thumb and in the absence of any better information I apply a 10 percent adjustment per degree C, that is, I reduce by 10 percent for each degree C above 20 C and increase by 10 per cent per degree below 20 C. Most manufacturers publish such information on their websites. Some developers, such as Rodinal, are very linear against temperature having only a single developing agent. Some developing agents are very sensitive to low temperatures and at some point their activity almost ceases completely.

[john_finch]

I f I may add...

What hasn't been mentioned, and is worth stating for the ab-initios to developing

film, is when to check the temperature.

 

The best time is half way through development. Just pop a clean (well rinsed)

thermometer down the center of the tank. There's usually a hole for it or for a 'turn

agitator'. Leave it there for 20 seconds or so and see what it reads. Then make your

adjustments to the dev time based on that temperature. It gives you an average

temperature of your development and helps to keep things a little more consistent.