Test strips look different to full size print (RA-4)

[Bumba]

Okay I think I've got to the bottom of this although I need to do some more printing to say for certain.

I use a Jobo drum and usually do a prewash of 30 seconds but I am not strict on the temperature of this wash as I didn't think it mattered. I keep my developer at 36°c. What I think is hsppehapp is that the prewash isn't warming up the drum sufficiently and this is causing the temp of the development to drop and a lack in density.

I did a test print using 2 x 30 sec 36°c prewashes to warm up the drum. My developer went in at 36°c and came out at 31°c but I had good density even though the colour was off.

Does anyone have any advice on msinmaintai temperature in a Jobo? Is it worth extending the prewash even further to heat up the drum? Is it worth starting the dev at 38°c so it averages out at 36°c during the process or does the temperature drop happen at the end of the process?

Thanks

 

[Tim Stapp]

You state that you are using a JOBO drum. Are you also using a JOBO processor or a roller base?

 

[koraks]

I tried the Jobo route once, with a paper drum om a CPE2 with the water bath at around 38C. No pre-rinse, just tipped the warm developer into the drum, which was a few degrees cooler at that point. No problems, but I used a few hundred ml of developer (reused, replenished). But I found it too much hassle messing around with a drum in comparison to a room temperature tray and development in the dark.

 

[Bumba]

Thanks for the advice Greg, that Kodak publication helped and I am also hand rolling it not using a Jobo processor.

I think I've achieved success and thought I'd post what I found incase anyone runs into the same problems as me in the future.

What I found that works in a Jobo drum is this:
3 x pre-wash for 30 secs each at 38.5°c using a decent amount of volume.
Develop for 45 secs (32s of agitation then 12s to drain) with dev starting at 36.5°c. When it comes out it measures at 33.5°c giving an average of 35°c and a drop of 3°c.

Complete the process as normal with Blix at the same temp and time as Dev. I use a stop bath and rinse after the development.

I use 3 pre-washes at a higher temp then the developer as I found this bring the drum up to temp the quickest and the 3 changes ensures that the water inside is always warm (I can feel the drum warming from the outside). keep my chemicals in a water bath that's 38.5°c which is the water I use for the pre-washes and because the water is at a higher temp, it stabilizes the dev at 36.5°c and by the time I'm ready to pour it, the temp hasn't changed.

At first I thought I was undeveloping because on my strip I had different filter values but they all looked very similar and I thought by developing for a bit longer it would increase the saturation and the difference between each filter value. What I found was that the different filters looked the same because I was overdeveloping and not underdeveloping which is not what I expected. When I brought my development more in line with 35°c at 45s I saw a larger difference between each filter value that made more sense.

I also ended up overdeveloping a strip (starting temp 39°c for 1 min) and what I found was that the curves went off. I had a a mix of red parts and some parts that looked fairly normal. Also all the filter values looked pretty much the same on the test strip. Also the density wasn't much different in the shadows than a properly developed strip.

That's what I found. Sorry for the long, rambling post but hopefully it helps someone out.
Thanks everyone for the help as I think I've got to the bottom of this.

Thanks everyone