QA-ing a mini-lab ...

[bob100684]

Having worked in labs that have used Fuji oasis to check control strips, a software program called Scandense/Windense, and doing it by hand.....By hand is by far the best. Getting an "ok" from oasis, or seeing a little green spedometer thing in scandense doesn't tell you much. Minilab output is crap not because they don't run control strips but because they fail to run upkeep prints, especially when changing paper rolls, racks in the machine aren't cleaned properly, scratch test leaders are usually not run, and in the case of scanner line problems involving frontiers, diffusion boxes aren't kept clean.

dmr, regarding your question on Y-max, I'm going to try to exceed the limit of your curiosity.

As analogsnob pointed out, it is a check on the bleach, where one measures the difference between the "black" patch and the yellow patch. Why? Well, the black patch has all 3 color layers heavily exposed, to make a maximum amount of cyan, magenta, and yellow dye, right? Ohterwise it wouldn't look black. So this puts the maximum strain on the bleach - maximum amounts of silver in all 3 layers have to be bleached out. So the first sign of a bleach problem should show up here.

You might think this black patch is all you need, but wait! What if the developer activity changes? Exactly! The black patch density will go up and down with developer variations. So how do you tell which one is causing the change? Now the reason for yellow patch becomes apparent. Whatever the activity of the developer, density of the yellow dye in both the black and the yellow patches will track closely together. However, when bleach begins to weaken, the first signs of failure will be seen in black. So by always comparing the two patches to each other, you have a very sensitive test for just the bleach.

Today, most places probably use a computer program to check the control strip plots, so it's not necessary to understand the guts of the process. The computer will advise on any possible problems, at least within the realm of what it can "see". I have to say that I'm a bit amused that you find it interesting; that is something of a rarity today.

[bob100684]

oh and p.s a good lab runs far more than one control strip per machine per day....

[benjiboy]

Ben
The quality is poor because it takes more than running control strips and printer tests. It is only the first step. Unfortunately, many labs don't do that.
The quality comes from having trained, committed and dedicated employees. It helps a lot if they love photography. I feel that we (photographers) get the quality we deserve (as a group or whole). We are looking for the cheapest film, cheapest processing and cheapest printing. It is so hard to make a living as a printer or lab tech.
Michael

I agree entirely Michael, as an American friend used to say years ago " if you pay peanuts you get monkeys". We agonize about the quality of our equipment, yet many of us buy the cheapest film and processing we can find, we might be better off in the final analysis buying less expensive gear and using more expensive film and labs.

[wogster]

Having worked in labs that have used Fuji oasis to check control strips, a software program called Scandense/Windense, and doing it by hand.....By hand is by far the best. Getting an "ok" from oasis, or seeing a little green spedometer thing in scandense doesn't tell you much. Minilab output is crap not because they don't run control strips but because they fail to run upkeep prints, especially when changing paper rolls, racks in the machine aren't cleaned properly, scratch test leaders are usually not run, and in the case of scanner line problems involving frontiers, diffusion boxes aren't kept clean.

Here is the question enquiring minds want to know, how often should a mini lab machine be shut down, drained and thoroughly cleaned?

[dmr]

If this is the case , why is the output of so many minilabs so poor ?

In my not so humble opinion, the bad thing about minilabs is that they are consistently inconsistent!

I've found that it's overall lack of attention to detail that have caused the problems I've been aware of.

I can't ever remember having negatives developed poorly, chemistry wise, that is. I have had cases where they have been scratched or fingerprinted. That's just poor technique.

Poor lab scans seem to be more common. I quit using one Walgreens because of blown highlights plus the fact that the staff did not seem to know what I was talking about it when I reported it.

When I first started getting DO-CD done, the one guy at the one Target' gave me very consistently good results. Then he quit (disappeared? transferred to lawn and garden?) and the scans were fuzzy and out of focus and nobody seemed to be able to do anything about it.

[bob100684]

Here is the question enquiring minds want to know, how often should a mini lab machine be shut down, drained and thoroughly cleaned?

filters on our film and paper processor are changed once a week(more often on busy weeks) Stabilizer on both is dumped once a week and the tanks and racks are thoroughly scrubbed. During this time, we also pull out all the other racks on the machine and scrub them out, but don't dump the chemistry usually. Developer/bleach/fixer is usualy only dumped when scrubbing racks/crossovers doesn't solve a scratching problem, or when t

[bob100684]

Here is the question enquiring minds want to know, how often should a mini lab machine be shut down, drained and thoroughly cleaned?

filters on our film and paper processor are changed once a week(more often on busy weeks) Stabilizer on both is dumped once a week and the tanks and racks are thoroughly scrubbed. During this time, we also pull out all the other racks on the machine and scrub them out, but don't dump the chemistry usually. Developer/bleach/fixer is usually only dumped when scrubbing racks/crossovers doesn't solve a scratching problem, or when there is some sort of chemistry control issue. Every 2-3 months I'll drain the other tanks just to make sure there isn't too much crap building up in them. Minilabs THEORETICALLY, with enough film/paper throughput should be able to run indefinitely without being dumped and remain well within process parameters.