Temperature Measurement

[enivre]

Hi guys,

I previously always just took temperature measurements of the water bath around my film developing tank until I realised that the temperature inside is actually much higher.

So I tried a roll which I allowed the temperature inside the tank to hit 20degC before I poured in the developer of the same temperature.

I followed the timings to the letter but ended up with under developed negs. I never had this when I measured the temperature externally via the water bath.

So which is the right way? I've heard that I should measure the internal temperature but it seems that that's not quite right.

I have two thermometers also, so it's nothing wrong with the thermometer.

Any advice?
Thanks!
Ervine

 

[waileong]

Measure your developer before you pour in. Make sure it's 20 deg. Then develop.

Whether you want to keep a water bath is up to you. I think the effect is minimal, unless you development time exceeds 15 mins.

Hi guys,

I previously always just took temperature measurements of the water bath around my film developing tank until I realised that the temperature inside is actually much higher.

So I tried a roll which I allowed the temperature inside the tank to hit 20degC before I poured in the developer of the same temperature.

I followed the timings to the letter but ended up with under developed negs. I never had this when I measured the temperature externally via the water bath.

So which is the right way? I've heard that I should measure the internal temperature but it seems that that's not quite right.

I have two thermometers also, so it's nothing wrong with the thermometer.

Any advice?
Thanks!
Ervine

 

[enivre]

Measure your developer before you pour in. Make sure it's 20 deg. Then develop.

Whether you want to keep a water bath is up to you. I think the effect is minimal, unless you development time exceeds 15 mins.

Yup it was at 20.

I'll try the w/o waterbath method instead. I suspect my waterbath continued to cool the developer below 20degC during the developing process.

I think the waterbath temperature was 15degC... :dunno:

Oh one more thing, how crucial is it for the fixer and stop to be at the same temp?

Thanks!
Ervine

 

[waileong]

Not critical. Normal room temp fine.

Oh one more thing, how crucial is it for the fixer and stop to be at the same temp?

Thanks!
Ervine

 

[maxonline]

based on my past experiences, i have habit of cooling the mixture to 18 degree b4 pouring into the tank....the temp will raise a little to close 20degree...

 

[enivre]

based on my past experiences, i have habit of cooling the mixture to 18 degree b4 pouring into the tank....the temp will raise a little to close 20degree...

okay I'll give that a whirl... thanks!

 

[alucard]

I usually follow what maxonline has mentioned, by pouring in the developer at 19degC. The outside temp in SG is quite high during daytime, and the temperature of your developer soup increases quite fast. So, I do all my development either during the night after 9:30~10PM, or early mornings.

For the stop bath (I use water) and fixer, I normally keep the stop bath around 22degC and fixer at close to room temp. So, by the time I complete development, the entire temperature changes are smooth and gradual. This prevents reticulation of the film emulsion (explained to me by a guru ).

cheers.

 

[enivre]

Thanks guys, will try this method later.

 

[maxonline]

I usually follow what maxonline has mentioned, by pouring in the developer at 19degC. The outside temp in SG is quite high during daytime, and the temperature of your developer soup increases quite fast. So, I do all my development either during the night after 9:30~10PM, or early mornings.

For the stop bath (I use water) and fixer, I normally keep the stop bath around 22degC and fixer at close to room temp. So, by the time I complete development, the entire temperature changes are smooth and gradual. This prevents reticulation of the film emulsion (explained to me by a guru ).

cheers.

for stop bath i use white vinegar 1:4, then wash with running water

 

[fastshot]

Since our ambient temperature here is quite high, one may consider developing the films at a higher temperature e.g. 24 degC instead of 20 degC. There are development charts that shows the development times corresponding to the higher temperature. From my personal experience, there is no noticeable problems associated with processing at 24C verses 20C, so long as the development times isn't shorter than 5 mins. This minimum time is to ensure full and even development.

One possible technique you may want to consider if you want to be very precise about temperature control is to pour in plain cooled water into the film development tank and sit the tank in cool water bath together with a bottle of developer solution until the temperature of all 3 items are at the desired temperature. Then pour out the water, and continue with the normal process.

There is really no need to use an acidic stop bath, just plain water is fine. There are certain advantages to "slow stop" using plain water. But if one insist on a stop bath, there is a need to be aware of compatibility of the acid stop solution with the developer and fixer being used. For home made stop bath, don't use household vinegar (smells), instead, go and get citric acid crystals from bakery shop (eg Phoon Huat). Citric acid crystals are cheap and all you need is 15g in 1 litre of water to make a stop bath.

 

[juggler]

Hi guys,

I previously always just took temperature measurements of the water bath around my film developing tank until I realised that the temperature inside is actually much higher.

So I tried a roll which I allowed the temperature inside the tank to hit 20degC before I poured in the developer of the same temperature.

I followed the timings to the letter but ended up with under developed negs. I never had this when I measured the temperature externally via the water bath.

So which is the right way? I've heard that I should measure the internal temperature but it seems that that's not quite right.

I have two thermometers also, so it's nothing wrong with the thermometer.

Any advice?
Thanks!
Ervine

Ervine:
I have 2 metal developer cans. One for cooling the developer in a water bath and the other containing the films.
I measured the developer temperature [inside] to be 20C before I pour it into the films. This is regardless of the outside water bath which is much colder.
During the agitation process, I believe the temperature of the film container could rise a bit maybe? So about every 2 minutes, I let it stand in the cold water bath for 15 to 30 sec.
When developing has completed, I checked that the developer temperature was close to 20C still . You can experiment and see.