Small Commercial C41 Labs - Chemistry Refresh Intervals?

One little miracle in my small corner of the photographic universe is the survival, against all odds, of the modest camera store serving my small, rural community. It's not perfect - a couple years ago the young, 20-something clerk working there didn't know what I was talking about when I came in and inquired "do you have any 35mm Delta 3200?" But still. It's nice having them there. Among other things, they still do C41 processing onsite. Two runs a week. Monday and Thursday.

I only shoot C41 once in a blue moon. But a couple months ago, having finished a roll of 120 Ektar, I had it processed at this local camera store. The basic processing was fine - colors, exposure of the 5x7 proof prints, etc. - all the stuff that the average consumer would look for, were good. But upon very detailed, very close inspection (preparatory to my making a very large print) there were countless tiny spots of color dye sprinkled over the image. Took forever to spot them out. I'm assuming these were tiny bits of dirt/debris in the chemistry. I can also surmise the lab doesn't get an awful lot of C41 work and that the chemistry doesn't get changed out with great frequency.

The question I'd pose, to those of you expert in C41 processing, is is there a suggested interval or volume where the chemistry is dumped and entirely fresh chemistry brought in? Or, like some good whiskeys, is the soup simply partially replenished at given intervals, such that there is no point where the chemistry is 100% fresh?

Or is there some other reason that would account for the dye spots?

I'm disinclined to make an issue of it with the store. I simply don't shoot enough C41 to worry that much. And I can imagine the challenge of continuing to operate a wet lab for what surely is only a tiny handful of remaining film customers. But if I knew, for instance, that the chemistry got replaced once a week, or once a month, or whatever, I'd be fine asking what their changeout schedule was. I have the option of a bigger lab closer into DC that caters to a professional clientele, but I'd like to support this local store if at all possible.

Thanks in advance...

[Edit: And I see I have dropped this into the wrong section - B&W. Argh. And I don't see a 'Delete' option. Apologies...]

Moved to the color forum.

Thanks, David. Much appreciated!

Hard to say for labs, but I doubt they fully dump and redo the chems if they are that low volume of c41, probably just replenish a lot. For home use I do it one shot so it is basically always fresh (i recycle bleach though). Back in the day, volume was higher, undoubtedly, at most labs.

Jager said:

Or, like some good whiskeys, is the soup simply partially replenished at given intervals

Click to expand...

Please tell me more about this whiskey replenisher you speak of, mine seems to just go bad inside of me the next day!

Proper replenishment should always keep the processing solutions producing results which are in spec, and the tank solutions should not need to be dumped and replaced other than for cleaning if excess dirt or tar accumulates on the transport, tank walls, etc., or due to some sort of contamination.

It sounds like your problem is not due to replenishment issues but dirt or contamination issues. It may be replenishing properly, but a general machine cleaning may be long overdue.

Many of the neer machines and adjusted processes have been designed with lower and less frequent throuputs in mind. Kodak's LORR chemical packaging comes to mind.

So the issue isn't just how often the chemicals are being replaced, but what types of machines and processes are being employed.