Chemical Quantities for Jobo 3005

Hi, I just received my Jobo CPP2 and its Expert Drum 3005 tank to

develop my 5x7 sheets. My first attempt to process 5x7 B&W sheets did

not turn too well. I used the chemical quantities guidelines on

Jobo's web site, i.e. 270ml of chemistry to process up to three 5x7

sheets. But the outcome is: only one of the three is good, one is

sort of "half developed" and third one is not. So, I guess this is a

matter of more chemical quantity. Any clue from experienced 3005

users ? what guidelines for chemical quantities would you recommend ?

Thanks in advance for your help, Joel

Two things you need to be carefull with. First is to make sure that your unit is absolutely level in both directions. If it is not, the chemistry will tend to stay in the lower end of the drum and more than likely cause the problem you described. Secondly, there are two ways to put the film in the drum. You can put the 7" side in the direction of the long side of the drum and you could also the 7" cross ways in the drum. I recommend that you put the film with the 7" in the direction of the long side of the drum. You also need to carefully push it down to the same depth in the drum emulsion side in. I have processed 5x7 film in this drum without a hitch, but I tend to try to get a full drum for consistency and I also usually round up to the next whole volume from the recommended volume processing chart. You must generate data with the volumes of chemistry you use because the ratio of sq inches of film to developer volume is critical to consistent results. I remember Sexton saying that he would put in a sheet of film exposed to sunlight as compensation for two image exposures if he needed to fill a drum.

 

If you are shooting a lot of 5x7, I would recommend the 3006 drum. Leave the 3005 for your 8x10. Just my two cents. Good Luck.

I have the same drum as well as a couple of 3010 drums. I always use around 800-900 ml to ensure complete coverage. Unfortunately Jobo is very optimistic when it comes to chemical quantities. When you do use sufficient chemistry you will find that the negs will be very even and consistent in quality.

Joel,

 

The minimum amount of developer stock solution will often

make the Jobo suggested minimum quantities irrelevant. Jobo

can only advise on the minimum amount of liquid to effectively

cover the surface of the film. For the amount of concentrate

needed to ensure full development you must refer to information

from the chemical manufacturer.

 

As a guide: T-Max RS requires 16.08 ml of concentrate for each

80 sq ins of film. a 5x7 is obviously 35 sq ins. I use T-Max RS at

1+9 which means that for three 5x7 sheets 241 ml of working

solution is necessary (I would round it up to 250ml. With Xtol it's

100ml per 80 sq ins and at 1+1 that means a minimum 300ml

working solution to reliably develop your three sheets.

 

Since you mention uneven and differing development I would

also suggest you go back to the beginning and start again,

double-checking all the relevant details:

 

Unit is level, (not just the unit itself but the drum in the unit!)

 

Rollers on lift are properly positioned,

 

Inlet nozzle on lift is aligned with mouth of drum,

 

Speed of rrotation is set to '4',

 

Drum rotates properly with the weight of solution contained

therein,

 

Film is placed in drum with emulsion side facing AWAY from the

wall of the chamber.

 

Technique of pouring chemistry into lift funnel is smooth, steady

and not too fast � a rush of chemistry will cause the fluid to

back-up and escape through the exit hose.

 

Just my thought s, good luck,

 

WG

While the previous threads suggest answers to your problem, i wonder if you use adequate developer. I belive that Jobo's recommendations on quantity apply to developer only. In some of their publications they clarify that a bit more. So if you use 240-250 ml of solution, with TmaxRS 1:9, you would use about24-25ml of developer and the rest water. itmay be you will need to increase volume of diluted solution to 500-600 ML .

Bob

I've gone by JOBO's recommened fluid amount for my 3005 for 8x10's and never had a problem. If you only got one of your three 5x7s developed it sounds like the problem is somewhere else. I think the first responder suggestions were right on. You shouldn't have to put in 800cc to do 3 5x7's.