Chemical X-Contamination in Tray Processing

[holmburgers]

So while processing 4x5's in small trays, undoubtedly a good amount of the chemicals are being transported by your fingers as you switch trays. I transfer 1 sheet at a time to the next solution, so for 5 sheets of film I'm dipping my fingers in one solution and then dipping them into the next solution 5 times. Contaminating both frontwards & backwards.

Now, with developer it's no problem as I just throw it out, but is this a concern with the 3 remaining chems? For economy I've been reusing stop, fixer & HCA.

Basically, I don't have a good feel for which combinations of chemicals are most detrimental to one another.

Is this a problem?, and if so, what do you do to mitigate it?

Thanks!

 

[holmburgers]

Just received a friendly PM....

I know about the developer being the most fickle, that is, no stop or fixer should get in there. This isn't a problem since I do one batch at a time and so once the developer has been contaminated, I'm done with it.

Otherwise, it sounds like the other 3 aren't as critical.

 

[Christopher Walrath]

Stop to fixer are definitely not SO much a worry as they are both acidic in nature, normally. But you are wise to be one batching the developer in this workflow.

 

[holmburgers]

Cool, thank you.

How about the HCA (hypo-clearing agent)?

I guess it shouldn't be a problem since you're supposed to rinse between fixer & HCA, though I must admit, i forgot to do this last time!

 

[Photo Engineer]

Lift out of the developer with the left hand and drain. Transfer to right hand and use that hand to immerse in stop or rinse while agitating with left in developer and right in next solution. Continue movement with your right hand from rinse or stop to fix as this contamination is insignificant. Keep the left free of all reverse contamination. Use it for developer only.

This assumes left to right work flow. Reverse if needed. Use rubber gloves.

Never get fix or stop or rinse into developer. The reverse is permissible that is, fix into stop or rinse for example.

Use right hand to transfer from fix to wash. Wash right hand as needed while transferring.

PE

 

[Doremus Scudder]

PE's method is very good. Mine is a bit different but has the same results. At the end of the developing time, I pick up the films from the developer, drain them and then move them to above the stop bath tray. I then fan them like a hand of cards and transfer them one-at-a-time into the stop (in the same order I immersed them in the developer so the time is exactly the same). After the films leave the developer, my hands never go back into the solution. The same procedure applies to the rest of the line (although as mentioned above, upstream contamination for the rest of the chemicals is not critical). Alternately, you can pick up the entire stack of films from the developer, drain well and then immerse the entire stack in the stop. Shuffle through the stack once and then start timing. I did this in the past, but now prefer the former method.

You should never have to have upstream contamination. There are lots of ways to avoid it. Do wear gloves as suggested above.

Best,

Doremus Scudder
www.DoremusScudder.com

 

[holmburgers]

Hmm, so far I've never worn gloves. I find dealing with the delicate 4x5's difficult enough in the dark. I can't really fan them with any confidence & I think gloves would make this all the more difficult. But, it's something to work towards.

And I don't want to develop dermatitis....

 

[Photo Engineer]

I use thin surgical gloves, purchased at the local drug store in boxes of 50.

I use interleaving agitation or do single sheets, and I can do deep and quick immersion using my hands, which minimizes any uneven wetting of the film with solution. I use the same method for paper and have done as many as 25 sheets of 8x10 at one time. The trick is to mark sheet #1 by clipping the corner and noting when it comes back to the top of the pile so that you always know where and when to start transferring sheets from one solution to the next.

Oh, and I always put the film or paper into the developer face down, but then flip the stack when all are in the developer. This gives more even solution contact and you don't touch the emulsion side with your fingers. The tray bottom must be smooth though to prevent scratches.

You must be careful not to trap an air bubble under the film or paper though.

PE